Microbial fertilizer and organic manure combined fertilization changes the rhizosphere bacterial community and carotenoids of Citrus reticulata Blanco ‘Orah’

doi:10.21203/rs.3.rs-4376678/v1

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Microbial fertilizer and organic manure combined fertilization changes the rhizosphere bacterial community and carotenoids of Citrus reticulata Blanco ‘Orah’

https://doi.org/10.21203/rs.3.rs-4376678/v1

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Background

Citrus reticulata Blanco ‘Orah’ is one of the most widely grown citrus varieties in southern China. It has been proven that microbial fertilizer and organic manure combined fertilization could improve the yields and appearances of ‘Orah’ fruits. However, details regarding the mechanisms underlying the effects of combined fertilization on the agronomic traits and rhizosphere bacterial community of plants still need to be elucidated.

Results

This study compared the rhizosphere bacterial community and carotenoids of ‘Orah’ with (WYT group) and without (WYCK group) combined fertilization. The WYT group was sprayed with 50 ml Strongreen and 250 g of Yumeiren five times while WYCK group did not sprayed. Combined fertilization increased fruit weight and the Citrus color index (CCI) significantly (P < 0.05). By 16s rRNA sequencing, 7,126 operational taxonomic units (OTU) were obtained. A higher Shannon index was observed in the WYT group compared to that in the WYCK group. Comparison between the two groups showed that Pseudomonas was enriched in the WTY group, and Cyanobacteria was enriched in the WYCK group. At the family level, Phyllobacteriaceae was significantly abundant in the WTY group, whereas Thermosporothrix and Sphingobium were significantly abundant in the WYCK group. A total of 51 carotenoid components were tested using UPLC-MS/MS. In the pulp tissues, 37 carotenoid components were decreased in the WTY group compared to those in the WYCK group. In fruit skin, 24 significantly different components (7 downregulated and 17 upregulated) were identified in WTY compared to those in WYCK. Correlation analysis revealed that the network between OTUs and carotenoids contained seven carotenoid components and four OTUs. Four OTUs, strain TRA3-20 (a eubacterium), Roseiflexus, OPB35, and Fictibacillus contributed to carotenoid accumulation regulation in fruit skin.

Conclusions

By exploring the complex interactions between soil microbiota and fruit traits, our research has illuminated potential pathways through which these microbial communities influence the biosynthesis and accumulation of carotenoids. In conclusion, this study provides valuable information regarding soil bacterial communities related to carotenoid accumulation in ‘Orah’.

Citrus reticulata

Bacterial communities

Carotenoids

Fertilization

16S rRNA

Soil health is crucial for plant growth because it provides a continuous living ecosystem and affects crop yield [1]. Fertilizers are used to improve the soil environment. However, long-term chemical use usually damages the soil environment and disrupts ecosystems [2]. For example, probiotics in the soil can be dramatically changed by chemical fertilizers [3]. Recently, microbial fertilizers and organic manure have been developed to address these problems [4, 5]. The combined use of microbial fertilizers and organic manure leads to comprehensive changes in the soil ecosystem, contributing to high crop yields [6, 7]. The Strongreen and Yumeiren used in this study contained various strains of microorganisms and fermented organic fertilizers developed by Jiangmen Jieshi Plant Nutrition Co., Ltd. and Guangxi Yuanrun Agricultural Development Co., Ltd., respectively. They can improve soil health by stimulating probiotic growth and depressing the growth of pathogenic bacteria [8]. Although the beneficial effects of the combined use of Strongreen and Yumeiren on soil have been determined, more details regarding its mechanism are needed to guide its practical application.

The fruit color of Citrus affects the price and market competitiveness [9]. Thus, the cause of different fruit colors has received widespread attention. The fruits have vivid colors that are mainly determined by anthocyanins and carotenoids. Anthocyanins are a class of water-soluble flavonoids that are widely distributed in vegetables and fruits [10]. Plants rich in anthocyanins, such as grapes, apples, and cabbage, exhibit color diversity that may appear red, purple, blue, or black [10]. Carotenoids are produced by plants, bacteria, archaea, and fungi. They present as yellow, orange, and red organic pigments [11]. Citrus plants are a rich source of carotenoids. Carotenoids constitute a large family of compounds produced via comprehensive pathways. In addition, carotenoid concentrations are highly diverse among citrus varieties [12]. For example, satsuma mandarin (Citrus unshiu Marc.) However, violaxanthin isomers are enriched in Valencia oranges (Citrus sinensis Osbeck) [13, 14]. These different carotenoid components in fruits affect the nutritional composition of the juice sacs. Therefore, the carotenoid component is important for fruit color and juice sac quality.

Recent studies have shown that the rhizosphere bacterial community contributes to plant health and affects plant growth. Network interactions of the rhizosphere bacterial community can induce carotenoid production in plants. For Citrus planting, a combination of microbial fertilizer and organic manure fertilization has been widely used in recent years (Das et al., 2014). This combined fertilization increases fruit yield and optimizes fruit color. Unfortunately, we still lack information about the interaction between rhizosphere bacterial community and carotenoid accumulation driven by microbial fertilizer and organic manure combined fertilization. In this study, we used two fertilizers, Strongreen and Yumeiren, to treat the Citrus reticulata Blanco ‘Orah’. Strongreen contains biological fulvic acid (BFA), organic matter, humic acid, manganese, boron, zinc (3–5%), and potassium oxide (≥ 6%). Yumeiren contains organic fertilizers used for the enzymatic hydrolysis of fish proteins and peanut bran. These two fertilizers have been widely used in South China to promote plant growth for pitaya (Hylocereus undatus), banana (Musa acuminata), and ‘Orah’ [8].

Based on previous planting knowledge, we presumed that the combined fertilization of Strongreen and Yumeiren might affect the rhizosphere bacterial community and lead to the accumulation of several carotenoids. In this study, we compared the fruit characteristics of Orah plants with and without combined fertilization of Strongreen and Yumeiren. The rhizosphere bacterial community and carotenoids in the two groups were determined by 16S rRNA gene sequencing and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) analysis, respectively. Using bioinformatics analysis, the differences in diversity and taxa of the rhizosphere bacterial community, and carotenoid components, were identified. Finally, rhizosphere bacterial community–carotenoid pairs with high correlations were analyzed, and an interaction network was constructed. The details of the effects of combined fertilization on rhizosphere bacterial community and carotenoids in ‘Orah’ has not been unveiled yet. Thus, the results would provide valuable information for understanding the mechanism of microbial fertilizer and organic manure combined fertilizer.

2.1 Field experiments and sampling

The studied ‘Orah’ in this study were growing in a local orchard in Wuming town from Nanning, Guangxi. The plants were grown from 2017 to 2022 and grown at the same management conditions as described previously [15]. The longitude and latitude positions of experimental place were 23°15′58″and 108°17′23″E, respectively. The annual average temperature was 22.3°C, the average temperature of the coldest month was 13.2°C, the average temperature of the hottest month was 28.8°C, the average annual precipitation was 1272.3 mm, and the average annual sunshine duration was 1509.3 hours. Lighting is natural light. All tested plants assigned to the groups were randomly selected. The 60 trees were randomly divided into two groups: WYT and WYCK groups. The WYT group was sprayed with 50 ml Strongreen and 250 g of Yumeiren (diluted in 10 kg ddH₂O) five times every month from July to November from 2017 to 2022. Sampling and measurements were double-blind [16]. For each group, 100 g of rhizosphere soil samples from five trees with three replicates were collected using a sampling shovel for 16S rRNA gene sequencing. Briefly, sterilize shovels were used to sample the rhizosphere soil. After removing impurities such as plant roots, stones, etc., from the soil, a portion of the soil sample was preserved in an insulated box containing ice packs and brought back to the laboratory, where it was immediately stored in a -80°C freezer for microbial analysis. For each group, three fruit replicates were obtained in January 2023 for the UPLC-MS/MS analysis.

2.2 Measurements of fruit

The weight, cross diameter, and longitudinal diameter of the ‘Orah’ fruit were measured following the standard method as previously described on ripening stage. The color of the ‘Orah’ fruit was determined by UltraScan Pro (Hunter Lab, Reston, VA, USA) under room temperature per the L, a, b standard color. Citrus color index (CCI) was used to evaluate fruit color. The CCI was calculated as CCI = (a × 100)/L × b.

2.3 DNA extraction and sequencing

For 16s rRNA sequencing, DNA from the rhizosphere soil samples (5g for each sample) was extracted using the TIANamp Soil DNA Kit (TIANGEN, China) according to the manufacturer’s protocols. DNA was assayed using a 1% agarose gel and a NanoDrop 2000 spectrophotometer (NanoDrop, USA) to confirm its quality and calculate its concentration. Sequence fragments of bacterial DNA from the 16S rRNA genes were amplified using polymerase chain reaction (PCR). The primers were 341F: 5′- CCTAYGGGRBGCASCAG-3′ and 806R: 5′-GGACTACNNGGGTATCTAAT-3′ as reported before [16].. Three biological replicates were used for each treatment group. The PCR reaction condition was: 98°C for 30 s, followed by 25 cycles (98°C for 10 s, 55°C for 30 s, and 72°C for 30 s), and a final extension at 72°C for 5 min. After PCR, the products were isolated by 2% agarose gel electrophoresis and Agencourt Ampure XP beads (Beckman, USA), following the PicoGreen dsDNA quantitation assay (Thermo Fisher, USA). The sequencing libraries were constructed by a TruSeq® DNA PCR-Free Sample Preparation Kit (Illumina, USA), determined by an Agilent Bioanalyzer 2100 (Agilent, USA), and sequenced using an Illumina NovoSeq 6000 platform (Illumina, USA). All the raw sequencing data have been deposited in the NCBI SRA database under the BioProject number PRJNA1090555.

2.4 Bioinformatic analysis of soil bacterial communities

The generated raw reads were filtered to eliminate adaptors, primers, low-quality sequences, nonbacterial ribosome sequences, and chimeras. The sequences were then assembled by FLASH v1.2.11 [17] following clustered into operational taxonomic units by CD-HIT algorithm using the UCLUST program (USEARCH V11, https://www.drive5.com/usearch/). Diversity comparisons were analyzed for alpha and beta diversity using QIIME2 plugins [18]. The Bray-Curtis distances and square-root transformed abundance data were analyzed and visualized by the “phyloseq,” “dplyr”, and “ggplot2” R packages.

2.5 Analysis of carotenoids in 'Orah'

Carotenoid content was analyzed using UPLC-MS/MS (Wuhan MetWare Biotechnology Co., Ltd., Wuhan, China). The fruit skin and pulp from WYCK and WYT groups were first crushed into powder by an MM 400 Grinding Mill (Retsch, Germany) at 4°C. The analyzed groups were named WYCKS (fruit skin of the WYCK group), WYCKP (fruit pulp of the WYCK group), WYTS (fruit skin of the WYT group), and WYTP (pulp of the WYT group). Then, 50 mg samples were dissolved in 0.6 ml extraction buffer (n-hexane/acetone/ethanol with a volume of 1:1:2 containing 0.01% BHT). After adding the standard substance and treated for 20 min at room temperature, the samples were isolated by 12000 r/min centrifugation for 5 min at 4°C twice. Samples were dissolved in a methanol/methyl tert-butyl ether (1:1) mixture. By filtration into 0.22 µm pore size, the samples were analyzed by a UPLC-MS/MS system. The system included an ExionLC™ AD (https://sciex.com.cn/) and a QTRAP® 6500+ (https://sciex.com.cn/) using the ESI mode. The condition for ExionLC™ AD was as follows: chromatographic column, YMC C30 (3 µm, 100 mm × 2.0 mm i.d.); mobile phase A was methanol:acetonitrile (1:3), 0.01% BHT and 0.1% formic acid and mobile phase B was methyl tert-butyl ether (containing 0.01% BHT); the gradient elution program was 0 min A/B 100:0 (V/V), 3 min 100:0 (V/V), 5 min 30:70 (V/V), 9 min 5:95 (V/V), 10 min 100:0 (V/V), 11 min 100:0 (V/V); the flow rate was 0.8 mL/min, column temperature was 28°C, and the injection volume was 2 µL. The mass spectrometry used a 350°C Atmospheric Pressure Chemical Ionization Source. In QTRAP® 6500+, the Declustering Potential and Collision Energy methods were used for the detection. The data were processed using the Analyst 1.6.3 software (Sciex). Scheduled multiple reaction monitoring was used for the analysis, and the Multiquant 3.0.3 software (Sciex) was used to quantify the carotenoids. The declaration of potentials and collision energies as key mass spectrometer parameters were analyzed for optimization.

2.6 Statistical analysis

All statistical analyses and plots in this study were performed using R software. Alpha and beta diversities were calculated after normalization, and the Shannon diversity index was used to represent alpha diversity. Beta diversity was presented using a Bray–Curtis dissimilarity matrix and permutational analysis. Correlation analysis between microorganisms and carotenoids was performed using the correlation package of R.

3.1 Fruit quality and soil content

The fruit quality of the two groups was assessed (Fig. 1A). The fruit weight, cross diameter, longitudinal diameter, and color were compared. Fruit weight was significantly higher in the WYT group than in the WYCK group (P < 0.05) (Fig. 1B). The fruit color differed significantly between the WYT and WYCK groups. The analysis results, including L, a, b, and CCI, were significantly different between the groups (P < 0.05) (Fig. 1C-F).

3.2 Analysis of alpha and beta diversity

The 16s rRNA sequencing generated 736,037 clean sequences, and 683,533 sequences (92.87%) were effective in generating 7,126 operational taxonomic units (OTU) (Supplementary Table S1). Shannon and Simpson indices were used to analyze the genus diversity of the WYT and WYCK groups. The WYT group showed a higher Shannon index than the WYCK group (P < 0.05, Fig. 2A), whereas similar Simpson indices were observed when comparing the WYT and WYCK groups (P > 0.05, Fig. 2B). The Curtis similarity and PCA were performed to show the overall divergence in bacterial community composition between the groups (Fig. 2C, D). The replicate samples from the WYT and WYCK groups demonstrated similar results; however, a significant separation between the two groups was observed.

3.3 Bacterial diversity of 'Orah'

Most of the OTU were assigned into 10 phyla, accounting for 95.41%, including Proteobacteria (30.70%), Chloroflexi (13.55%), Acidobacteria (14.96%), Actinobacteria (17.19%), Cyanobacteria (3.82%), Saccharibacteria (3.71%), Verrucomicrobia (2.82%), Gemmatimonadetes (3.35%), Firmicutes (2.30%) and Bacteroidetes (3.01%) (Supplementary Table 2, Fig. 3). The top three phyla in the WYT group were Proteobacteria (34.00%), Actinobacteria (16.77%), and Acidobacteria (15.69%), whereas those in the WYCK group were Proteobacteria (27.39%), Actinobacteria (17.61%), and Chloroflexi (16.02%). Only 4.59% of the taxa observed in the two groups were not assigned to the top 10 phyla.

3.4 Rhizosphere bacterial community changes in 'Orah' with microbial fertilizer and organic manure combined fertilization

The comparison of microbiota in the rhizosphere soil between the WYT and WYCK groups was performed by discriminant analysis of the effect size. The results demonstrated that Pseudomonas was significantly enriched in WYT, whereas Cyanobacteria were significantly enriched in WYCK (P < 0.05, Student’s t-test) (Fig. 4). At the family level, Phyllobacteriaceae was significantly more abundant in the WTY group than in the WYCK group (P < 0.05). Thermosporothrix and Sphingobium were significantly more abundant in the WYCK group than in the WTY group (P < 0.05) (Fig. 5) (Supplementary Tables S3-4).

3.6 Carotenoid changes in 'Orah' with microbial fertilizer and organic manure combined fertilization

A total of 51 carotenoid components were identified using UPLC-MS/MS (Fig. 6A). Among the identified carotenoid components, 37 were downregulated in WYCKP compared to those in WYTP. The comparison between WYCKS and WYTS identified 24 significantly different components, including 7 downregulated and 17 upregulated carotenoid components (Fig. 6B). The top 10 components with the most changes in WYCKP compared to WYTP comparison were violaxanthin myristate, α-cryptoxanthin, lutein dimyristate, zeaxanthin palmitate, violaxanthin dipalmitate, 5,6epoxy-luttein dilaurate, lutein oleate, lutein palmitate, violaxanthin-myristate-laurate, and violaxanthin dimyristate (Fig. 6C). By WYCKS and WYTS comparison, the most up-regulated 5 carotenoid components were zeaxanthin-laurate-myristate, zeaxanthin dilaurate, zeaxanthin dimyristate, lutein dilaurate, and antheraxanthin while the most up-downregulated 5 carotenoid components were violaxanthin dioleate, 8'-apo-beta-carotenal, violaxanthin-myristate-oleate, rubixanthin palmitate and β-cryptoxanthin palmitate (Fig. 6D) (Supplementary Table S5).

3.7 Correlations between rhizosphere bacterial community and carotenoids

The interactions between the rhizosphere bacterial community and carotenoids were evaluated using correlation analysis. The threshold of the p-value was < 0.0001 in this study. A total of 113 OTU-carotenoid pairs with high correlations were identified in skin tissue (Fig. 7A). In the pulp tissue, 88 OTU-carotenoid pairs with high correlations were observed (Fig. 7B). The overlap of the OTU-carotenoid pairs from the skin and pulp tissues was identified. Four OTUs were correlated with seven carotenoid components in the two tissues. The four OTUs were annotated as TRA3-20 (order), Roseiflexus (genus), OPB35 (class), and Fictibacillus (genus). The results showed that these groups of rhizosphere bacterial affected carotenoid generation in the fruit of “Orah.”

In this study, we compared the “Orah” under different fertilization conditions to investigate the changes in microbial fertilizer and organic manure combined fertilization. The characteristics of the fruits were compared, and the results showed significant changes in fruit color after combined fertilization. A brighter color was detected in the WYT group. Similar results have been reported for other Citrus varieties. For example, Magnesium (Mg) application can alter fruit coloration and sugar accumulation in navel orange (Citrus sinensis Osb.) [19]. Using Bacillus subtilis biofertilizer, a simultaneous color change in the fruit skin and pulp of Tarocco blood orange (Citrus sinensis (L.) Osbeck) was observed [20]. Although the effects of fertilizer application on fruit color have been investigated previously, knowledge of the underlying mechanisms is limited. Undoubtedly, combined microbial fertilizer and organic manure fertilization changed the rhizosphere bacterial community. Therefore, we assayed the bacterial community by rhizosphere soil 16s rRNA sequencing. In addition, to evaluate carotenoid accumulation in the different groups, carotenoids were analyzed using UPLC-MS/MS. Interaction networks between rhizosphere bacterial community and carotenoid components were constructed and key bacterial related to carotenoid accumulation were identified. Therefore, this study investigated changes in fruit color and provided mechanistic details from rhizosphere bacterial community insights using microbial fertilizer and organic manure combined fertilization.

The top 10 phyla with OTU were identical for the 'Orah' in the two groups. Thus, at the phylum level, the rhizosphere bacterial composition was similar with and without combined fertilization of Strongreen and Yumeiren. However, in the WYT group, Pseudomonas was enriched compared to the WYCK group. Pseudomonas, the major gram-negative bacteria phylum, contains several important genera and pathogenic bacteria. Some free-living bacteria of this phylum participate in nitrogen fixation. In this study, rhizosphere bacterial community, which are free-living bacteria, were obtained from the root microbial community. Palm oil seedlings (Elaeis guineensis Jacq.), sterilization, and chemical fertilizers change the Pseudomonadota community and contribute to the high nutrient transformation effectiveness [21]. Similar results were reported for Myrothamnus flabellifolia [22], winter wheat (Triticum aestivum L.) [23], and maize (Zea mays L.) [23]. Thus, it could be inferred that these enriched bacteria are responsible for nitrogen fixation and promote the production of the 'Orah' fruit. In the WYCK group, cyanobacteria, which are gram-negative bacteria, were enriched. Cyanobacteria can associate with other plants to fix nitrogen [24]. This study showed that the combined fertilization of Strongreen and Yumeiren regulates cyanobacteria. The details and their effects remain unknown and require further investigation.

This study revealed that 37 of the 51 carotenoid components tested were downregulated in WYCKP compared to those in WYTP. Surprisingly, all carotenoid components in the pulp were decreased by combined fertilization. In contrast, 7 downregulated and 17 upregulated carotenoid components were identified in the skin. These results indicated that the effects of combined fertilization on carotenoid component accumulation were different between the pulp and skin in the 'Orah' fruit. To date, many reports have demonstrated conserved carotenoid metabolism in different plant species. However, the carotenoid content under the different fertilization conditions was significantly different. For example, Magnesium treatment could increase the lutein, β-cryptoxanthin, zeaxanthin, and violaxanthin levels in the pulp of Satsuma mandarin (C. unshiu Marc.) [25]. The sulfur fertilization of spinach (Spinacia oleracea) can increase carotenoid levels [26]. The more vibrant colors of fruit skin in the combined fertilization 'Orah' are associated with the increasing of zeaxanthin-related components and lutein dilaurate and antheraxanthin. Carotenoids in the skin are yellow and red. Furthermore, the β-carotene pathway yielded a substantial amount of decomposition products among the decreased components. Thus, the results inferred that the more vibrant colors and higher juice yield by combined fertilization by increasing the products in the α-carotene pathway rather than the β-carotene pathway.

Correlation analysis identified an interacting network that included four OTUs and seven carotenoid components. The OTUs identified were TRA3-20 (order), Roseiflexus (genus), OPB35 (class), and Fictibacillus (genus). TRA3-20 is positively correlated with C and N metabolism [27]. Roseiflexus is the carotenoid source and grows photoheterotrophically [28]. OPB35 is a good predictor of total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP), which may contribute to soil health for plant growth [29]. Fictibacillus belongs to the Bacillaceae family. Several species of this genus can improve carbon metabolic properties and plays a role in promoting diversity in the rhizosphere microbial community [30, 31]. Soil health, including soil microbiome communication, is important for the interactions between microorganisms and plants. Rhizosphere bacterial community are crucial for soil metabolism. Our results demonstrated that the key microorganisms were strongly related to some carotenoid accumulation that participated in coloration of the ‘Orah’ skin. The seven carotenoid components that correlated with the OTUs were from both the lycopene ε-cyclase (LCYE)- and lycopene β-cyclase (LCYB)-mediated synthesis pathways. Microbial fertilizer and organic manure combined fertilization changed the bacterial community in the rhizosphere soil. Thus, we propose that the changes in carotenoids were driven by an improvement in rhizosphere bacterial community rather than by direct carotenoid synthesis pathway regulation.

In this study, we compared the fruit characteristics, rhizosphere bacterial community, and carotenoids in ‘Orah’. These results indicated that combined fertilization improved the bacterial community in the rhizosphere soil, which affected the soil environment. These effects contributed to better nutrient absorption of ‘Orah’ resulting in changes in carotenoid accumulation. Finally, fruit characteristics, including yield and skin color, were altered by combined fertilization. These results provide evidence for elucidating the mechanism of improved agronomic characteristics of fruits by microbial fertilizer and organic manure combined fertilization and provide clues to the microorganism-carotenoid regulatory network. Taken together, these findings provide valuable information regarding the fertilization strategy of ‘Orah’.

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Availability of data and materials

All the raw sequencing data have been deposited in the NCBI SRA database under the BioProject number PRJNA1090555.

Competing interests

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Funding

This work was funded by Science and Technology Major Project of Guangxi (GuiKeAA22036002, GuiKeAA20108003); Science and Technology Major Project of Nanning (20212141, 20222065), Guangxi Characteristic crop experimental station, China (GuiTS202201); Project of Guangxi Academy of Agricultural Sciences (Guinongke2021YT051, 2022JM32, 2023YM73); Functional expert of "Cultivation and Pest Control" in Guangxi Citrus Innovation Team of National Modern Agricultural Industry System (nycytxgxcxtd-2021-05-02); Citrus Huanglongbing prevention and control engineering technology research center of Guangxi.

Authors' contributions

Qichun Huang designed and performed the experiment and wrote the manuscript. Wei Zhou, Zhikang Zeng, Nina Wang, Yanxiao Huang, Hao Cheng, Quyan Huang, Jimin Liu and Fuping Liu performed the experiment and analyzed the data. Huihong Liao performed the bioinformatic analysis. Chengxiao Hu edited the manuscript. Dongkui Chen confirmed the experiment. Shaolong Wei, Chaosheng Li, and Zelin Qin supervised the experiment and edited the manuscript. All authors contributed to the article and approved the submitted version.

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No competing interests reported.

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Microbial fertilizer and organic manure combined fertilization changes the rhizosphere bacterial community and carotenoids of Citrus reticulata Blanco ‘Orah’

Status:

Version 1

Abstract

Background

Results

Conclusions

Figures

1 Introduction

2 Materials and methods

2.1 Field experiments and sampling

2.2 Measurements of fruit

2.3 DNA extraction and sequencing

2.4 Bioinformatic analysis of soil bacterial communities

2.5 Analysis of carotenoids in 'Orah'

2.6 Statistical analysis

3 Results

3.1 Fruit quality and soil content

3.2 Analysis of alpha and beta diversity

3.3 Bacterial diversity of 'Orah'

3.4 Rhizosphere bacterial community changes in 'Orah' with microbial fertilizer and organic manure combined fertilization

3.6 Carotenoid changes in 'Orah' with microbial fertilizer and organic manure combined fertilization

3.7 Correlations between rhizosphere bacterial community and carotenoids

4 Discussion

5 Conclusion

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1