As major pests in tea plantations, Matsumurasca onukii Matsuda (Hemiptera: Cicadellidae) and Dendrothrips minowai Priesner (Thysanoptera: Thripidae) reduce tea yields and cause large economic loss. Host plant resistance is one of the most effective and economical potential pest management strategies but is not well understood in tea. This study aimed to screen tea lines to determine chemical and structural traits that were associated with resistance to both herbivore species and then develop comprehensive resistance indicators and evaluation model of insect resistance. In addition, we modelled host plant identification and selection by the two pests and established resistance grading criteria for each. Traits positively associated with resistance to M. onukii were: concentrations of nonanal and dodecane, epidermal thickness of adaxial leaf surface, and ratio of this to leaf thickness. Negatively associated traits were: concentrations of malonic dialdehyde and linalool, ratio of adaxial leaf cuticle thickness to leaf thickness, and ratio of abaxial cuticle thickness to leaf thickness. For D. minowai, length of leaf, trichome density of buds, and caffeine content were positively associated with resistance; whilst dodecane and phenethyl alcohol concentrations as well as several color parameters of foliage were negatively associated. To comprehensively evaluate the insect resistance of tea cultivars, the affiliation function method was used and the results of the model showed significantly correlation for observed population densities of both pests. This study provides the first comprehensive framework for host plant resistance traits and will underpin risk assessment among existing cultivars and selection in future plant breeding programs.
Research Article
Construction of a comprehensive evaluation model for constitutive resistance traits of tea cultivars to the pests Matsumurasca onukii and Dendrothrips minowai
https://doi.org/10.21203/rs.3.rs-5248171/v1
This work is licensed under a CC BY 4.0 License
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tea plant
tea green leafhopper
tea thrip
constitutive resistance
affiliation function
- Study on the constitutive resistance traits of tea cultivars to the pests Matsumurasca onukii and Dendrothrips minowai.
- First constructed comprehensive resistance evaluation systems of tea plants to M. onukii and D. minowai.
- Resistance grading criteria were formulated for tea plant to the two sap-sucking pests.
- Screening of tea germplasm resistant to M. onukii and D. minowai.
The tea plant Camellia sinensis (L.) O. Kuntze, is one of the most important cash crops globally and central to human culture in China (Yu et al. 2021a). Tea plants typically produce multiple rounds of new shoots each year, so these high value harvestable plant parts are vulnerable to herbivores for an extended period of plant growth (Liao et al. 2019). The tea green leafhopper, Matsumurasca onukii Matsuda (Hemiptera: Cicadellidae) and the thrips, Dendrothrips minowai Priesner (Thysanoptera: Thripidae) are the main pests in tea plantations in China (Bian et al. 2016; Mei et al. 2017). The nymphs and adults of the sap-sucking pests feed mainly on the sap of new shoots, which cause direct damage to tea plants, such as sap loss and chlorophyll destruction. Additionally, pest oviposition damages the tender stem tissue which hinders the translocation of nutrients and water, resulting in the scorching of leaves (Jin et al. 2012). The phenology of these pests leads to alternating infestations and significantly inhibited growth of tea cultivars. The population peak of M. onukii occurs from mid-May to late-June and from September to November, while that of D. minowai occurs from mid-May to late-June and from September to October (Bian et al. 2016; Tian et al. 2018).
In heavy infestations, more than 50% of tea yield can be lost to these pests and the control costs account for more than 60% of the total control cost of tea plant diseases and pests (Chen et al. 2019). At present, management of these pests is mainly by agricultural chemical, physical, and biological control measures such as pruning, spraying pesticides, sticky boards, and releasing natural enemies (Hazarika et al. 2009). The cost of these approaches is high and the sustainability of insecticides is threatened by resistance developing in the pest populations as well as risks of environmental pollution, food residues, and farm-worker safety (Li & Kannan 2020a et al. 2023). Accordingly, more sustainable ‘green’ methods have become one of the major goals in agricultural research (Yu et al. 2021b). Screening insect-resistant cultivars can not only reduce dependence on insecticides and avoid associated risks, but also improve the sustainability of crop systems, which is one of the main strategies of green prevention and control (Hazarika et al. 2009). Common insect resistance research methods include measurement of field population density or honeydew production, life table analysis, and electrical penetration graph (EPG) studies (Jin et al. 2012; Sun et al. 2020; Guruswamy et al. 2023; Hsin et al. 2023).
During the co-evolution of insects and plants, tea has evolved complex systems of constitutive and induced resistance that can operate across the three stages of selection of host plants by pests: orientation, landing, and contact (Visser et al. 1986). Constitutive defense operates continuously irrespective of herbivore attack, conferred by many physical traits such as pubescence, waxiness, cuticle thickness as well and chemical traits that can repel pests or make the plant tissues less palatable or even toxic, though the chemistry of a given plant taxon can be recognized by specialist herbivores of that taxon as location and recognition cues (Ishveen & Rupesh 2023). Tea plants produce (E)-2-hexenal, (Z)-3-hexenyl, and linalool, volatiles that are strong attractants for M. onukii, and a terpenoid volatile (E)-nerolidol was identified as a potent signal that elicits plant defense. (Mu et al. 2012, Chen et al. 2020). Meanwhile, in olfactometer tests, M. onukii were significantly attracted to α-farnesene and repelled to β-caryophyllene by Lun et al (2023). Tea plants hinder the growth of insect pests by producing anti-nutrient proteins, toxic secondary metabolites including caffeine and tea polyphenol (Ceja-Navarro et al. 2015; Sun et al. 2020). Bioassays by Jin et al. (2016) showed that γ-aminobutyric acid may be the key factor affecting the feeding behavior of M. onukii. In terms of physical resistance, insect-resistant tea cultivars tend to have thicker leaf epidermis and denser pubescence whilst longer trichomes are associated with lower resistance to insects (Tissier et al. 2017; Andama et al. 2020).
Although multiple studies have explored the effects of single or small numbers of plant traits on insect resistance, such a narrow scope limits the extent to which resistance as an overall phenomenon is understood and the capacity to screen existing cultivars and optimize breeding programs. Hence, it is necessary to use comprehensive evaluation analysis methods to screen insect-resistant tea cultivars for the wide range of potential chemical and non-chemical traits that may be involved in constitutive resistance. Comprehensive evaluation is a method of analysis of multiple indicators, including analytic hierarchy process (AHP) (Grošelj & Dolinar 2023), grey correlation method (Jiang et al. 2023), and the membership function method (Zou et al, 2024). Among available methods, the membership function method is widely used to evaluate the quality of many kinds of crops, such as phytotoxicity assessment of dandelion exposed to microplastics (Li et al. 2023), and systematic evaluation of spice quality (Zou et al, 2024). It incorporates each individual trait into a comprehensive indicator, which can be used to express overall resistance of a plant cultivar to a given biotic threat.
Accordingly, this study first constructed a comprehensive resistance evaluation system of tea plants to M. onukii and D. minowai. Secondly, the significant correlation indicators of locational resistance, physical resistance, and chemical resistance were screened experimentally. Combining these results led to more efficient assessment models. Further, based on available data, a dynamic route for host plant selection by M. onukii and D. minowai was simulated. Finally, the reliability of the derived model was verified by the membership function method, and the resistance classification standard of tea cultivars M. onukii and D. minowai using cluster analysis. These results provide a theoretical and practical platform for improved breeding of tea germplasm resources and the control of key pests.
Text plants and insect source
Eleven tea cultivars were used in this study: Baijiguan (BJG), Baimudan (BMD), Baiyaqilan (BYQL), Dahongpao (DHP), Fujianshuixian (FJSX), Huangdan (HD), Huangguanyin (HGY), Huangmeigui (HMG), Meizhan (MZ), Ruixiang (RX), and Zijuan (ZJ). These were grown under uniform conditions in a tea plantation at the Wuyi Star tea plant germplasm repository, Fujian Province, China (118º0′3.82″ E, 27º42′48.99″ N). Samples of new shoots (one bud and two leaves) were collected in 2019, immediately frozen in liquid nitrogen and stored at -80◦C for subsequent analyses. Founders of M. onukii were collected from cv. Fuyun 6 within the same germplasm repository in May 2022. Thereafter, this insect was reared on branches of cv. Fuyun 6 held in water-retentive floral foam in insect cages in a greenhouse (25 ± 1℃, L14/D10 cycle, 70 ± 5% RH). Adults within one day of eclosion were selected as the test insects.
Construction of comprehensive evaluation system of constitutive resistance
The insect-resistance comprehensive evaluation system for tea cultivars was constructed using the aforementioned AHP method (Grošelj & Dolinar 2023). This approach formed a comprehensive resistance indicator for each cultivar based on three, broad, level 2 indicators (Fig. 1) that considered the colour properties and volatile emission from differing plant parts, physical traits, chemical traits; with each of these three indicators made-up of at least 24 specific traits.
Identification of resistant for tea cultivars
To measure field population densities of pests on each tea cultivar, the population size of M. onukii and D. minowai was assessed on 50 randomly-selected new shoots for each of five replicates on each cultivar. Surveys were conducted approximately every 7 days, from 6 June to 26 October 2021 and from 25 May to 27 July 2022. A total of 28 inspections were conducted.
Determination of the locational and selectional indicators of color parameters and volatiles
The color parameters of the third leaf of tea shoots were measured using an automatic colorimeter (ADCI, Chentaik Instrument Technology Co., Beijing, China) at the Wuyi Star tea plant germplasm repository, including luminance value (L*), range from red to green (a*), range from blue to yellow (b*), saturation (Sab), and chromaticity (Cab). Both the adaxial and abaxial surfaces of leaves were measured. Fresh leaf volatiles of one bud and two leaves of tea plant were measured by solid-phase microextraction (Lv et al. 2014).
Determination of the structural indicators
The length, width, trichome density, and area of one bud and three leaves of each plant were assessed according to the protocol of Zaman et al. (2023). Wax layer content per unit leaf area was determined according to Zhu et al. (2023). The thickness of palisade tissue, mesophyll tissue, adaxial and abaxial epidermis, adaxial and abaxial cuticle and leaf were measured with the paraffin section method (Sun et al. 2020). The following ratios were calculated, palisade tissue thickness to mesophyll tissue thickness, palisade tissue thickness to leaf thickness, mesophyll tissue thickness to leaf thickness, adaxial epidermis thickness to leaf thickness, abaxial epidermis thickness to leaf thickness, adaxial cuticle thickness to leaf thickness, abaxial cuticle to leaf thickness.
Determination of the chemical indicators
Twenty-four chemical traits were derived based on primary metabolites, secondary metabolites, and enzyme active substances. The content of free amino acids, polyphenols, and catechin components were determined using the methods of Sun et al. (2020). The content of soluble sugars was determined by the anthrone colorimetry method and total flavonoids determined by the aluminum trichloride colorimetry. Anthocyanin, chlorophyll a, chlorophyll b, carotenoid, total protein, peroxidase (POD), and malonic dialdehyde (MDA) were determined by Liu et al. (2021) and Gao et al. (2023).
Bioassay
Verification of chemical resistance indicators of tea plants
To explore the effect of chemical resistance index on M. onukii, the feeding method of Jin et al. (2016) was adapted. Petri dishes (14 cm in diameter and 1.5 cm in height) were used as feeders and, to ensure adequate ventilation, 30 holes were evenly punctured in the lid. A 1 cm2 piece of moistened filter paper was placed inside the feeder assemblies along with a 3 cm2 piece of cotton gauze as a carrier for 1 mL of artificial diet. On three occasions each day, 0.5 mL of purified water was added to the filter paper. Each insect was transferred to a newly-prepared feeder each day using a soft bristled paint brush. There were 35 replications for each treatment.
Infestation experiment
To test for a correlation between MDA and resistance to M. onukii, a pest infestation experiment was conducted. At the beginning of June, all tea cultivars were pruned and sprayed with 5% natural pyrethrins. Next, insect nets were erected on each cultivar. After a week, another spraying was carried out to ensure the tea branches were free of insects. When these tea plants grew new buds, a bud and two leaves of approximately the same size were collected as experimental branches. Individual shoots were inserted into 1 cm2 of floral foam and subsequently placed in a Petri dish (14 cm in diameter and 1.5 cm in height). Next, a one-day-old adult of M. onukii was added into the dish for 24 h. The control treatment excluded inclusion of an insect. The treatments were replicated thirty times for each cultivar and were performed in the same greenhouse. The DHP cultivar was not tested for pests as it did not grow shoots.
Statistical analysis
To compare field population dominance of M. onukii and D. minowai, the temporal niche breadth and the niche overlap were calculated by the Shannon-Wiener diversity index (Wang et al. 2021) and Pianka's niche overlap index (Liordos & Kontsiotis 2020), respectively. The results of insect-resistance evaluation of tea cultivars were calculated by the affiliation function method (Jan 2019). Duncan’s test of one-way ANOVA in IBM SPSS Statistics 26 was used to analyze the locational and sectional, structural, and chemical traits. Insect resistance classes were clustered using the Euclidean distance method, and population densities and indicators were correlated using the Pearson algorithm. The t test was used to analyze the significance of differences among tea cultivars.
Grade identification of resistance for tea cultivars
Both M. onukii and D. minowai were present in the field survey with marked temporal effects on population densities and large differences among tea cultivars (Fig. 2). Resistance of cultivars to M. onukii (Fig. 3A) and D. minowai (Fig. 3B) were classified into four classes by analyzing the population densities through clustering. In two consecutive years, the temporal ecological niche overlap indicators of the two sap-sucking pests were greater than 0.5, indicating significant ecological niche overlap, though D. minowai had significantly higher temporal ecological niche breadth than M. onukii and was dominant in terms of temporal ecological niche (Table 1).
|
Species |
Ecological niche breadth index |
Ecological niche overlap index |
|||
|
2021 |
2022 |
2021 |
2022 |
||
|
M. onukii |
1.22 ± 0.06B |
0.94 ± 0.02B |
0.72 ± 0.02 |
0.82 ± 0.02 |
|
|
D. minowai |
1.78 ± 0.02A |
1.40 ± 0.03A |
|||
The range of overlap index (O) is 0–1, and the higher the O value is, the higher the overlap degree of the two sap-sucking pests is. O > 0.3 indicates that the niche overlap is influential, and O > 0.6 indicates that the niche overlap is significant (Liordos & Kontsiotis 2020). Data were analyzed by column, and different capital letters in the table indicate significant differences between treatments by Duncan’s test (P < 0.05).
Screening indicators of the host selectional and locational resistance
Color parameters and volatilizes were involved in the location and selection of host cultivars by the two sap-sucking pests. Among them, L*s, L*a, b*s, b*a, Cabs, Caba, Saba, 1-nonanal, and dodecane, were significantly negatively correlated with the population density of M. onukii (P < 0.05). Linalool was positively correlated with the population density of M. onukii (P < 0.05). Population density of D. minowai was significantly positively correlated with L*s, L*a, b*a, Caba, dodecane, and phenethyl alcohol (P < 0.05; Table 2).
Screening indicators of structural resistance
Thickness of adaxial epidermis and the ratio of adaxial epidermis thickness to leaf thickness were significantly negatively correlated with the population density of M. onukii (Table 3). The ratio of adaxial cuticle thickness to leaf thickness and abaxial cuticle thickness to leaf thickness were significantly positively correlated with the population density of M. onukii (P < 0.05). Additionally, there were significant differences in trichome densities among tea cultivars (Fig. 4A). In the physical structure of tea plant, the length of leaves, and trichomes density of buds were positive indicators of resistance to D. minowai (Fig. 4B)
Screening indicators of chemical resistance
The population density of M. onukii was positively correlated with tissue concentration of GCG, catechin, anthocyanin pigment, and MDA, whilst negatively correlated with free amino acids. For D. minowai, only caffeine content was negatively correlated with the population density (Table 4).
Data analyzed by column. All data in the table are correlation coefficients, and asterisks show significant levels. Each saliency level is associated with a sign: P value (0.01: **, 0.05: *). M. onukii and D. minowai in the table represent the population density of M. onukii and D. minowai, respectively. The subscript containing ‘s’ is an indicator of the abaxial surface of the blade, and the subscript containing the ‘a’ is an indicator of the adaxial blade
Table 3. Correlation between population density and structural indicators of M. onukii and D. minowai
Table 4. Correlation between population density and chemical indicators of M. onukii and D. minowai
Peroxidase (POD), malondialdehyde (MDA), (-)-Gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-catechin(C), (-)-epicatechin (EC), (-)-epigallocatechin gallate (EGCG), gallocatechin gallate (GCG), (-)-epicatechin gallate (ECG), gallic acid (GA), theobromine (TB), theophylline (TP), caffeine (CAF), chlorophyll a (Chla), chlorophyll b (Chlb)
Bioassays
Significant changes in MDA content were observed among tea cultivars after being fed upon for 24 hours by M. onukii. MDA content generally decreased, except for cv. BJG, which increased (Fig. 5A). Further analysis showed that there was a significant negative correlation between population density of M. onukii and Δ MDA (P < 0.05). Further, the higher the MDA content, the weaker the resistance. Meanwhile, when the tea was damaged by M. onukii, the greater the change of the MDA content in leaf tissue, the more serious the damage was and the weaker the insect resistance (Fig. 5B).
Development of M. onukii, differing, biologically relevant concentrations were added to artificial diet. Overall, the survival rate and survival period fell with GCG concentrations. On day 2, the survival of M. onukii dropped below 50% and, from day 2 to day 4, survival rates decreased significantly faster with increasing GCG concentration (Fig. 5C). At all GCG concentrations, M. onukii died within eight days. The mean survival periods of M. onukii were 3.01, 2.51, and 1.96 d at GCG of 0, 0.025, and 0.050 g·L− 1, respectively. The t test of the data showed that there was a highly significant difference in the survival periods between 0 and 0.050 g·L− 1 (P < 0.05; Fig. 5D). Anthocyanins had no significant effect on the survival rate (Fig. 5E) and survival time (Fig. 5F) of M. onukii. The bioassay experiments demonstrated that MDA and GCG were effectively resistant indicators of tea plants to M. onukii.
Construction of a comprehensive evaluation model
Combining the above experimental results, a comprehensive evaluation model of the insect resistance of tea plants was constructed. In this model, eight indicators were associated with tea plant resistance to M. onukii. Among them, 1-nonanal, dodecane, adaxial epidermal thickness, and adaxial epidermal thickness to leaf thickness were positive resistance indicators, while linalool, adaxial cuticle thickness to leaf thickness, abaxial cuticle thickness to leaf thickness, and MDA content, were negatively associated with resistance (Fig. 6A). For D. minowai, nine indicators were related to resistance. Length of leaf, trichome density of tea bud, and CAF content, were positive indicators, whilst, dodecane, phenethyl alcohol, L*s, L*a, b*a, and Cab*a, were negative indicators (Fig. 6B).
Plant traits that operate as cues for the localization and selection of tea cultivars by the two sap-sucking pests were modelled on the basis of indicators related to insect resistance (Fig. 6C). In the case of coexistence of the two sap-sucking pests, when selecting hosts at a distance, D. minowai preferred tea cultivars with yellowish-green, brightly-colored leaves, and M. onukii tended to select tea cultivars with darker-colored leaves. At close range, D. minowai tended to choose tea cultivars with high relative contents of phenethyl alcohol and dodecane volatiles, while M. onukii tended to choose tea cultivars with high relative contents of linalool and low relative contents of nonanal and dodecane volatiles. When infesting tea plants, D. minowai preferred to feed on tea cultivars with less dense trichomes, shorter leaves, and low content of CAF. M. onukii preferred to feed on tea cultivars with thin leaf epidermis, thick cuticle, and high content of MDA.
Model validation results
The weighted resistance values of cultivars to M. onukii showed that BJG was the highest (6.73) and ZJ was the lowest (0.25), with the descending order: BJG > BMD > HGY > DHP > HMG > FJSX > HD > RX > BYQL > MZ > ZJ (Table 5). In the case of D. minowai, a contrasting trend was apparent with cultivar ZJ the highest (8.75) and BJG lowest (0.96) with a descending rank of resistance of ZJ > FJSX > MZ > BMD > DHP > RX > HD > HGY > BYQL > HMG > BJG (Table 6). Verifying the resistance model, the resistance values were significantly (P < 0.001), negatively correlated with observed population density values (Fig. 7A). In order to identify tea cultivars with insect resistance, the combined results of the classification of the comparison model and the classification by population density. Cultivars SX, DHP, and BMD all showed moderate resistance to both of the sap-sucking pests (Fig. 7B). Based on the results of the integrated evaluation cluster analyses, preliminary resistance grading criteria were formulated for the two sap-sucking pests (Table 7).
|
Cultivar |
Mo1 |
Mo2 |
Mo3 |
Mo4 |
Mo5 |
Mo6 |
Mo7 |
Mo8 |
Mo |
|---|---|---|---|---|---|---|---|---|---|
|
BJG |
0.69 |
1.65 |
0.89 |
0.88 |
0.96 |
1.00 |
0.33 |
0.33 |
6.73 |
|
BMD |
0.95 |
0.90 |
1.00 |
0.93 |
0.48 |
0.41 |
0.32 |
0.30 |
5.28 |
|
HGY |
0.70 |
0.85 |
0.74 |
0.93 |
1.00 |
0.40 |
0.27 |
0.22 |
5.10 |
|
DHP |
1.00 |
0.70 |
0.91 |
0.97 |
0.72 |
0.00 |
0.43 |
0.36 |
5.09 |
|
HMG |
0.57 |
1.15 |
0.54 |
1.00 |
0.50 |
0.56 |
0.42 |
0.33 |
5.07 |
|
FJSX |
0.49 |
0.50 |
0.96 |
0.92 |
0.81 |
0.00 |
0.53 |
0.37 |
4.57 |
|
HD |
0.41 |
1.00 |
0.83 |
0.65 |
0.00 |
0.57 |
0.40 |
0.43 |
4.30 |
|
RX |
0.67 |
0.40 |
0.50 |
0.92 |
0.65 |
0.62 |
0.23 |
0.22 |
4.21 |
|
BYQL |
0.79 |
0.00 |
0.91 |
0.71 |
0.00 |
0.43 |
0.34 |
0.28 |
3.45 |
|
MZ |
0.62 |
0.70 |
0.04 |
0.76 |
0.00 |
0.00 |
0.31 |
0.19 |
2.62 |
|
ZJ |
0.00 |
0.25 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.25 |
Mo1: linalool, Mo2: upper cuticle/leaf, Mo3: lower cuticle/leaf, Mo4: MDA, Mo5: 1-Nonanal, Mo6: dodecane, Mo7: upper epidermis, Mo8: upper epidermis/leaf, Mo: Represents the weighted value of the function value of M. ounkii.
|
Cultivar |
Dm1 |
Dm2 |
Dm3 |
Dm4 |
Dm5 |
Dm7 |
Dm8 |
Dm9 |
Dm10 |
Dm |
|---|---|---|---|---|---|---|---|---|---|---|
|
ZJ |
0.84 |
1.00 |
1.00 |
1.00 |
1.40 |
0.65 |
0.37 |
0.50 |
0.65 |
7.41 |
|
FJSX |
1.00 |
1.00 |
0.74 |
0.69 |
0.92 |
0.49 |
1.00 |
1.00 |
0.49 |
7.33 |
|
MZ |
0.37 |
1.00 |
0.73 |
0.68 |
0.89 |
0.57 |
0.60 |
1.00 |
0.57 |
6.41 |
|
BMD |
0.79 |
0.60 |
0.74 |
0.75 |
1.00 |
0.33 |
0.36 |
0.67 |
0.33 |
5.57 |
|
DHP |
0.85 |
1.00 |
0.64 |
0.51 |
0.89 |
0.44 |
0.18 |
0.67 |
0.44 |
5.62 |
|
HD |
0.64 |
0.43 |
0.68 |
0.51 |
0.81 |
1.00 |
0.28 |
0.50 |
1.00 |
5.85 |
|
RX |
0.42 |
0.38 |
0.68 |
0.70 |
0.95 |
0.41 |
0.47 |
0.17 |
0.41 |
4.59 |
|
HGY |
0.60 |
0.60 |
0.36 |
0.33 |
0.63 |
0.37 |
0.27 |
0.67 |
0.37 |
4.20 |
|
BYQL |
0.63 |
0.57 |
0.39 |
0.25 |
0.67 |
0.05 |
0.24 |
0.50 |
0.05 |
3.35 |
|
HMG |
0.00 |
0.44 |
0.40 |
0.29 |
0.50 |
0.31 |
0.13 |
0.00 |
0.31 |
2.38 |
|
BJG |
0.46 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.50 |
0.00 |
0.96 |
Dm1: phenethyl alcohol, Dm2: dodecane, Dm3: L*s, Dm4: L*a, Dm5: b*a, Dm7: Caba, Dm8: length of leaf, Dm9: trichomes of tea bud, Dm10: CAF, Dm: Represents the weighted value of the function value of D. minowai.
|
Resistance classification |
M. onukii (Mo) |
D. minowai (Dm) |
|---|---|---|
|
Susceptible |
0 ≤ Mo ≤ 1 |
0 ≤ Dm ≤ 4 |
|
Moderately susceptible |
1 < Mo ≤ 4 |
4 < Dm ≤ 6 |
|
Moderately resistant |
4 < Mo ≤ 6 |
6 < Dm ≤ 7 |
|
Resistant |
Mo > 6 |
Dm > 7 |
Accurate identification of the precise traits at play in conferring resistance to particular pest species in a given crop type, along with an understanding of their relative importance, is key to the essential capacity to screening breeding lines in and to understand the vulnerability of existing cultivars. In the present study, through a series of field, laboratory, and greenhouse experiments, we explored the constitutive resistance traits of tea plants involved in defence against to two major pests, M. onukii and D. minowai. This involved the construction and validation of an efficient and convenient evaluation model of the insect resistance of tea cultivars.
To lay the groundwork for screening for resistance-related indicators, eleven tea cultivars were graded for insect resistance through the results of two consecutive years of field surveys. Field population density is the key indicator for the identification of resistance to sap-sucking pests and is also the most intuitive expression of the strength of the insect resistance of tea plant (Sun et al. 2020). Temporal niche overlap of the two pests was high, with M. onukii and D. minowai damaging tea plants asynchronously within the same broader time period. The more numerous species was found to be D. minowai, which also had a wider time niche breadth indicating its plasticity and fuller utilization of resources (Immanuel et al. 2022).
Foliage color parameters play an important role in location-related resistance. Phototaxis is one of the inherent behavioral characteristics of pests, which affects the feeding, mating, and reproduction of pests (Huang et al. 2023). We found higher numbers of D. minowai on brightly and highly saturated yellow color tea cultivars, while higher numbers of M. onukii were associated with tea cultivars with darker leaves and low saturated yellow. Importantly, the observed phototactic preferences of M. onukii differed from that reported in previous studies (Bian et al. 2014) in which M. onukii, as well as D. minowai, were most strongly attracted to brightly colored, and highly saturated yellow color. The color parameters related to the population density of M. onukii was not included in the model in this study as no indoor phototropic inductive experiments were conducted as D. minowai are more dominant in the temporal ecological niche and have a higher preference for leaf color.
Volatile compounds produced by host plants provide important chemical information for host location of herbivorous pests (Degenhardt et al. 2009). Here we find that linalool, 1-nonanal, and dodecane were the key host location cues of M. onukii, while phenethyl alcohol and dodecane were key for D. minowai. This information is of practical importance as a foundation for future development of pest control strategies based on luring or repellence such as in push-pull strategies or trap-and-kill approaches (Kirk et al. 2021).
When pests overcome resistance traits based on host plant location cues, structural traits become important (Myers & Sarfraz 2017). In the study, it was found that the longer the leaf and the more trichomes of the tea bud, the fewer D. minowai were present on foliage. During the growth of new shoots, the longer the leaves were, and the larger the leaf areas were, the harder the blade was. Trichome coverage can prevent pests from reaching the leaf surface and impede movement over the foliage reducing feeding activity (Li et al. 2022). Trichomes also secrete specialized defensive metabolites, including volatile terpenes which exert toxic or repellent effects on herbivores (Simmons et al. 2005; Andama et al. 2020). Thus, tea cultivars with longer leaves and more trichomes were more resistant to D. minowai. In contrast, M. onukii was more sensitive to the characteristics of leaf tissue structure. The thicker the adaxial epidermis thickness and the higher the ratio of abaxial cuticle thickness to leaf thickness, the greater the cultivar’s resistance to M. onukii. Thickness and stiffness of the leaf blade are important mechanical factors affecting feeding by pests (Simmons & Gurr 2006). In the present study, susceptibility to M. onukii were associated with high ratios of adaxial cuticle thickness to leaf thickness and abaxial cuticle thickness to leaf thickness. Another foliar trait, cuticle wax is crucial to reducing water loss but here we find that it is also associated with defense against M. onukii.
When pests overcome the physical barrier of plant foliage, antibiosis-related resistance traits, based on secondary metabolite production or altering nutrient and defensive enzymes, become central to defense (Treutter 2006). Tea plants were more resistant to M. onukii when the concentrations of MDA, GCG, and anthocyanins were low and free amino acids were high. When the content of CAF in tea plants was higher, resistance to D. minowai was stronger. CAF is a bitter substance that stimulates nerve excitation and has an important disruptive effect on the growth of pests that causes hyperactivity (Ceja-Navarro et al. 2015). Free amino acids are composed of a variety of components, and γ-aminobutyric acid (GABA) may be involved in the defense of tea plant against M. onukii. However, amino acids are made up of a variety of components and it is not possible to use a single criterion to represent the entire free amino acids. Therefore, only the bioassay experiments of GCG anthocyanins, and MDA were conducted. The lower the content of MDA in tea plants, the stronger the insect resistance to M. onukii; when tea was infested by M. onukii for 24 h, the greater the change of content of MDA, the more serious the damage and the weaker the insect resistance, the smaller the change, and the stronger the insect resistance. MDA is the product of membrane lipid peroxidation in plants under stress. Plants will accumulate a large amount of MDA under stress, and its content is proportional to the degree of stress (Bailly et al. 1996). Artificial diet studies with M. onukii revealed survival rate decreased with concentration of GCG but this was contrary to the earlier finding that higher the content of GCG in tea plant tissue, the weaker the resistance of tea cultivars to M. onukii. Anthocyanins in artificial diet had no significant effect on growth and development. Therefore, GCG and anthocyanin were not included in the overall model.
In this study, eight resistant traits associated with M. onukii and ten resistant traits associated with D. minowai were identified and characterized. To verify the reliability of the comprehensive evaluation model of tea plant resistance to the two sap-sucking pests, the affiliation function method was used. According to the contribution rate, the corresponding affiliation function values of each comprehensive indicator were calculated, and the comprehensive evaluation values of different insect resistance of tea plants were obtained after weighting. From this, the eleven tea cultivars were divided into four types by cluster analysis, and the weighted value and field population density were compared by correlation analysis. The results showed that the method balances the insect resistant indicators, simplifies the calculation and improves the accuracy of the evaluation results. The final screening showed that ZJ was the least resistant to M. onukii but the most resistant to D. minowai. In contrast, BJG had the strongest resistance to M. onukii but the weakest resistance to D. minowai. Among cultivars, FJSX, DHP, and BMD had strong resistance to both of these sap-sucking pests.
Earlier studies on the resistance of tea to these pests are more basic in focusing on changes in plants before and after being fed upon by pests and usually focus on a restricted range of traits. Reflecting this, we have lacked methods to efficiently and comprehensively evaluate insect-resistant tea cultivars. Accordingly, the significance of the present work is to have identified key resistance traits of the two most important pests of tea in China and integrated these into an overall model. Aside from the significance of this body of fundamental knowledge to host plant resistance, the utility of this model is to provide a more objective and comprehensive tool for assessing the degree of insect resistance of tea plants. Among breeding program lines, this can support selection and guide potential manipulation of traits. Among existing cultivars in commercial use, the model can inform pest management strategies according to the resistance levels of cultivars, to calibrate the need for use of complementary plant protect in measures such as biological control of pesticides.
In this study, different tea cultivars in the same habitat were used as test materials, and the resistance indexes of tea cultivars to the two sap-sucking pests were preliminary investigated through field trials and indoor validation experiments. In addition, an integrated evaluation model of insect resistance of tea plants was constructed, and the grading standards of tea plant resistance to the two pests were formulated, with a view to providing a theoretical basis for tea cultivation, breeding and pest control.
Author contribution
Yue Sun: Writing – review & editing, writing – original draft, visualization, software, methodology, investigation, formal analysis, data curation. Li-lin Chen: Writing – review & editing, guidance. Shan Jin: Review & editing, guidance, data analysis. Wen-qi Ye: Investigation, data analysis. Jia Liu: Investigation, data curation. Chen-xi Gao: Methodology, guidance. Jiu-mei Gao: Investigation, Data logging. Shi-xian Cao: Resources. Shun-tian Yu: Investigation, data logging. Zhi-hua Zhao: review & editing, guidance. Geoff M Gurr: Writing – review & editing, writing, formal analysis, data curation. Weijiang Sun: Project administration, funding acquisition, conceptualization. All authors reviewed the manuscript.
Funding
This study was supported by the Fujian Agriculture and Forestry University Construction Project for Technological Innovation and Service System of Tea Industry Chain (K1520005A01/K1520005A04), Ningde City Industry-University Cooperation Project (Ningde City Industry-University Cooperation Project), Cross-Strait "Three-Teas Integration" Standard Common Pilot Project, and State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Corps (SKL2022004), Special Fund for Science and Technology
Innovation of Fujian Zhang Tianfu Tea Development Foundation (FJZTF01).
Data availability
No datasets were generated or analyzed during the current study.
Conflict of interest
The authors declare they have no conflict of interest. All authors contributed critically to the drafts and gave final approval for publication.
Ethical Statements
Ethical statements do not applicable to this manuscript.
Publisher's Note
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- Andama, J. B., Mujiono, K., Hojo, Y., Shinya T., and Galis, I. (2020). Nonglandular silicified trichomes are essential for rice defense against chewing herbivores. Plant, Cell & Environment, 43(9): 2019-2032. https:// doi.org/10.1034/j.10.1111/pce.13775
- Bailly, C., Benamar, A., Corbineau, F., and Come, D. (1996). Changes in malondialdehyde content and in superoxide dismutase, catalase and glutathione reductase activities in sunflower seeds as related to deterioration during accelerated aging. Physiologia Plantarum, 97(1): 104-110. https://doi.org/10.1034/j.1399-3054.1996.970116.x
- Bian, L., Sun, X. L., Luo, Z. X., Zhang, Z. Q., and Chen, Z. M. (2014). Design and selection of trap color for capture of the tea leafhopper, Empoasca vitis, by orthogonal optimization. Entomologia Experimentalis et Applicata, 151(3): 247-258. https://doi.org/10.1111/eea.12191
- Bian, L., Yang, P. X., Yao, Y. J., Luo, Z. X., Cai, X. M., and Chen, Z. M. (2016). Effect of trap color, height, and orientation on the capture of yellow and stick tea thrips (Thysanoptera: Thripidae) and nontarget insects in tea gardens. Journal of Economic Entomology, 109(3): 1241-1248. https://doi.org/10.1093/jee/tow007
- Ceja-Navarro, J. A., Vega, F. E., Karaoz, U., Zhao, H., Stefan J., Chien, L. H. et al. (2015). Gut microbiota mediate caffeine detoxification in the primary insect pest of coffee. Nature communications, 6(1): 7618. https://doi.org/10.1038/ncomms8618
- Chen, L. L., Yuan, P., Pozsgai, G., Chen, P., Zhu, H. P., and You, M. S. (2019). The impact of cover crops on the predatory mite Anystis baccarum (Acari, Anystidae) and the leafhopper pest Empoasca onukii (Hemiptera, Cicadellidae) in a tea plantation. Pest Management Science, 75(12): 3371-3380. https://doi.org/10.1002/ps.5489
- Chen, S. L., Zhang, L. P., Cai X M., Li, X., Bian, L., Luo, Z. X. et al. (2020). (E)-Nerolidol is a volatile signal that induces defenses against insects and pathogens in tea plants. Horticulture research. 7(1): 52. https://doi.org/10.1038/s41438-020-0275-7
- Degenhardt, J., Hiltpold, I., Köllner, T. G., Frey, M., Gierl, A., Gershenzon, J. et al. (2009). Restoring a maize root signal that attracts insect-killing nematodes to control a major pest. Proceedings of the National Academy of Sciences of the United States of America, 106(32): 13213-13218. https://doi.org/ 10.1073/pnas.0906365106
- Gao, C. X., Sun, Y., Li, J., Zhou, Z., Deng, X. M., Wang, Z. H. et al. (2023). High light intensity triggered abscisic acid biosynthesis mediates anthocyanin accumulation in young leaves of tea plant (Camellia sinensis). Antioxidants, 12(2): 392. https://doi.org/10.3390/ANTIOX12020392
- Guruswamy, M., Marimuthu, M., and Moshe, C. (2023). Life table analyses for the tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae): effects of plant genotype. Pest management science, 79(6):2117-2125. https://doi.org/10.1002/PS.7392
- Grošelj, P., and Dolinar, G. (2023). Group AHP framework based on geometric standard deviation and interval group pairwise comparisons. Information Sciences, 626: 370-389. https://doi.org/10.1016/J.INS.2023.01.034
- Hazarika, L. K., Bhuyan, M., and Hazarika, B. N. (2009). Insect pests of tea and their management. Annual Review of Entomology, 54(1): 267-284. https://doi.org/10.1146/annurev.ento.53.103106.093359
- Hua, B., Chang, J., Wu, M. L, Xu, Z. J., Zhang F. Y., Yang, M. N. et al. (2021) Mediation of JA signaling in glandular trichomes by the woolly/SlMYC1 regulatory module improves pest resistance in tomato. Plant Biotechnology Journal, 19(2): 375-393. https://doi.org/10.1111/pbi.13473
- Huang, M., Meng, J. Y., Zhou, L., Yu, C., and Zhang, C. Y. (2023). Expression and function of opsin genes associated with phototaxis in Zeugodacus cucurbitae Coquillett (Diptera: Tephritidae). Pest Management Science. https://doi.org/10.1002/ps.7651
- Hsin, C., Aurang, K., Gholamhossein, G., Remzi, A., Mehmet, S. Ö., Ali, G. et al. (2023). Advances in theory, data analysis, and application of the age-stage, two-sex life table for demographic research, biological control, and pest management. Entomologia Generalis, 43 (4): 705-732. https://doi.org/10.1127/entomologia/2023/2048
- Immanuel, M., Bnaya, S., and Shnerb, N. M. (2022). How the storage effect and the number of temporal niches affect biodiversity in stochastic and seasonal environments. PLoS Computational Biology, 18(3):1-21. https://doi.org/10.1371/journal.pcbi.1009971
- Ishveen, K., and Rupesh, K. (2023). Trichomes mediate plant-herbivore interactions in two Cucurbitaceae species through pre-and post-ingestive ways. Journal of Pest Science, 96: 1077-1089. https://doi.org/10.1007/s10340-023-01611-x
- Jan, C. (2019). A new membership function approach to uncertain functions. Fuzzy Sets and Systems, 387: 68-80. https://doi.org/10.1016/j.fss.2019.04.013
- Jin, S., Chen, Z. M., Backus, E. A., Sun, X. L., and Xiao, B. (2012). Characterization of EPG waveforms for the tea green leafhopper, Empoasca vitis Göthe (Hemiptera: Cicadellidae), on tea plants and their correlation with stylet activities. Journal of Insect Physiology, 58(9): 1235-1244. https://doi.org/10.1016/j.jinsphys.2012.06.008
- Jin, S., Sun, X. L., Zhang, X. Z., Ye, N. X., and Chen, Z. M. (2016). Chemical analysis of 8 tea cultivars with different levels of resistance to Empoasca vitis Göthe and a preliminary identification of the chemical basis of this resistance. Chinese Journal of Applied Entomology, 53(3): 516-527. http://doi.org/0.7679/j.issn.2095-1353.2016.067 (In Chinese)
- Jiang, Q., Liu, W., and Wu, S. P. (2023). Analysis on factors affecting moisture stability of steel slag asphalt concrete using grey correlation method. Journal of Cleaner Production, 397. https://doi.org/10.1016/J.JCLEPRO.2023.136490
- Kirk, W. D.J., Kogel, W. J. D., Koschier, E. H., and Teulon, D. A. J. (2021). Semiochemicals for thrips and their use in pest management. Annual Review of Entomology, 66: 101-119. https://doi.org/10.1146/annurev-ento-022020-081531
- Léa, T., Céline, F., Louisiane, B., Hervé, J., Karine, M., Gilles, D. R. et al. (2023). Pesticide contamination in an intensive insect predator of honey bees. Environment International, 176: 107975. https://doi.org/10.1016/j.envint.2023.107975
- Li, P. H., Zhang, Y. R., Ye, Z. L., Zuo, H., Li, P., Zhao, X. C. et al. (2022). Roles of trichomes in tea plant resistance against multiple abiotic and biotic stresses. Beverage Plant Research, 2(1): 1-13. https://doi.org/10.48130/BPR-2022-0014
- Li, J. A., and Kannan, K. (2020). Profiles of urinary neonicotinoids and dialkylphosphates in populations in nine countries. Environment International, 145: 145106120-106120. https://doi.org/10.1016/j.envint.2020.106120
- Li, X. F., Ullah, S., Chen, N., Tong. X., Yang, N., Liu, J. et al. (2023). Phytotoxicity assessment of dandelion exposed to microplastics using membership function value and integrated biological response index. Environmental Pollution. 333: 121933-121933. https://doi.org/10.1016/J.ENVPOL.2023.121933
- Liao, Y. Y., Yu, Z. M., Liu, X. Y., Zeng, L. T., Cheng, S. H., Li, J. L. et al. (2019). Effect of major tea insect attack on formation of quality-related nonvolatile specialized metabolites in tea (Camellia sinensis) leaves. Journal of Agricultural and Food Chemistry, 67(24): 6716-6724. https://doi.org/10.1021/acs.jafc.9b01854
- Liu, J. L., Sun, J. H., Pan, Y. G., Yun, Z., Zhang, Z. K., Jiang, G. X. et al. (2021) Endogenous melatonin generation plays a positive role in chilling tolerance in relation to redox homeostasis in litchi fruit during refrigeration. Postharvest Biology and Technology, 178. https://doi.org/10.1016/J.POSTHARVBIO.2021.111554
- Liordos, V. and Kontsiotis, V. J. (2020). Identifying important habitats for waterbird conservation at a Greek Regional Nature Park. Avian Research. 11(1): 39. https://doi.org/10.1186/s40657-020-00224-7
- Lun, X. Y., Xu X. X., Zhang Y., Zhang, R. R., Cao, Y. Zhang X. Z. et al. (2023). An antennae-enriched odorant-binding protein EonuOBP43 mediate the behavioral response of the tea green leafhopper, Empoasca onukii Matsuda to the host and nonhost volatiles, Journal of Agricultural and Food Chemistry, 71(50): 20000-20010. https://doi.org/10.1021/ACS.JAFC.3C07144
- Lv. S. D., Wu., Y. S., Li., C. W., Xu., Y. Q., Liu., L., and Meng., Q., X. (2014). Comparative analysis of Pu-erh and Fuzhuan teas by fully automatic headspace solid-phase microextraction coupled gas chromatography-mass spectrometry and chemometric methods. Journal of Agricultural and Food Chemistry, 62(8): 1810-8. https://doi.org/10.1021/jf405237
- Mei, X., Liu, X., Zhou, Y., Wang, X. Q., Zeng, L. T., Fu, X. M. et al. (2017). Formation and emission of linalool in tea (Camellia sinensis) leaves infested by tea green leafhopper (Empoasca (Matsumurasca) onukii Matsuda). Food Chemistry, 237(15): 356-363. https://doi. org/10.1016/j.foodchem.2017.05.124
- Mu, D., Cui, L., Ge, J., Wang, M. X., Liu, L. F., Yu, X. P. et al. (2012). Behavioral responses for evaluating the attractiveness of specific tea shoot volatiles to the tea green leafhopper, Empoaca vitis. Insect Science, 19(2): 229-238. https://doi.org/10.1111/j.1744-7917.2011.01476.x
- Myers, J. H., and Sarfraz, R. M. (2017). Impacts of insect herbivores on plant populations. Annual Review of Entomology, 62(1): 207-230. https://doi.org/10.1146/annurev-ento-010715-023826
- Simmons, T. A., McGrath, D., and Gurr, M. G. (2005). Trichome characteristics of F1 Lycopersicon esculentum × L. cheesmanii f. minor and L. esculentum × L. pennellii hybrids and effects on Myzus persicae. Euphytica, 3144: 313-320. https://doi.org/10.1007/s10681-005-8002-x
- Simmons, T. A., and Gurr, M. G. (2006). Trichomes of Lycopersicon species and their hybrids: effects on pests and natural enemies. Agricultural and Forest Entomology, 7: 265-276. https://doi.org/10.1111/j.1461-9563.2006.00271.x.
- Sun, Q. Y., Chen, W. L., Ge, C. M., Ye, T., Zhang, R., and Zhang, J. X. (2020). Correlation of tea green leafhopper occurrence with leaf structure and biochemical components in different tea cultivars. International Journal of Pest Management, 69(2): 109-119. https://doi.org/10.1080/09670874.2020.1857882
- Tian, Y. Y., Zhao, Y. H., Zhang, L. X., Mu, W., and Zhang, Z. Q. (2018). Morphological, physiological, and biochemical responses of two tea cultivars to Empoasca onukii (Hemiptera: Cicadellidae) infestation. Journal of Economic Entomology, 111(2): 899-908. https://doi.org/10.1093/jee/toy011
- Tissier, A., Morgan, A. J., and Dudareva, N. (2017). Plant volatiles: going ‘in’ but not ‘out’ of trichome cavities. Trends in Plant Science, 22(11): 930-938. https://doi.org/10.1016/j.tplants.2017.09.001
- Treutter, D. (2006). Significance of flavonoids in plant resistance: a review. Environmental Chemistry Letters, 4(3): 147-157. https://doi.org/10.1007/s10311-006-0068-8
- Visser, J. H. (1986). Host odor perception in phytophagous insects. Annual Review of Entomology, 31(1): 121-144. https://doi.org/10.1146/annurev.en.31.010186.001005
- Wang, X. J., Dallimer, M., Scott, C. E., Shi, W. T., and Gao J. X. (2021). Tree species richness and diversity predicts the magnitude of urban heat island mitigation effects of greenspaces. Science of the Total Environment. 770: 145211 https://doi.org/10.1016/J.SCITOTENV.2021.145211
- Yu, Y. C., Xing, Y. X., Liu, F. J., Zhang, X., Li, X. W., Zhang, J., and Sun, X. L. (2021a). The laccase gene family mediate multi-perspective trade-offs during tea plant (Camellia sinensis) development and defense processes. International Journal of Molecular Sciences, 22(22): 12554. https://doi.org/10.3390/ijms222212554
- Yu, L. L., Chen, C., Niu, Z. H., Yang, G., Yang, H. R., and Xue Z. H. (2021b). Risk aversion, cooperative membership and the adoption of green control techniques: evidence from China. Journal of Cleaner Production, 279: 123288. https://doi.org/10.1016/j.jclepro.2020.123288
- Zaman, F., Zhang E., Xia L., Deng X. L., Ilyas M., Ali, A. et al. (2023). Natural variation of main biochemical components, morphological and yield traits among a panel of 87 tea [Camellia sinensis (L.) O. Kuntze] cultivars, Horticultural Plant Journal, 9(3): 563-576. https://doi.org/10.1016/J.HPJ.2022.08.007
- Zhu, L., Zeng, F. L., Liang, Y. P., Wang, Q., Chen, H. W., Feng, P. L. et al. (2023). Small papillae regulated by SPD25 are critical for balancing photosynthetic CO2 assimilation and water loss in rice. Rice, 16: 58. https://doi.org/10.1186/s12284-023-00676-7
- Zou Z. W., Guo B. J., Guo Y., Ma X. L., Luo S. S., Feng L. L. et al. (2024). A comprehensive “quality-quantity-activity” approach based on portable near-infrared spectrometer and membership function analysis to systematically evaluate spice quality: Cinnamomum cassia as an example. Food Chemistry, 439. https://doi.org/10.1016/j.foodchem.2023.138142
No competing interests reported.