Genetic similarity coefficient of the 104 high-oleic peanut genotypes in the present study, as calculated by NTSYSpc 2.10e ranged from 0.4400 to 0.9333, with a mean value of 0.6953 (detailed data unshown), comparable to that in a previous study using AhMITE markers to analyze 115 peanut cultivars/lines (mean value = 0.6902) (Wang et al. 2013). In earlier reports on high-oleic peanut, where only SSR markers were exploited, the minimum similarity coefficient was in the range of 0.3250–0.3438, and the average similarity coefficient ranged from 0.6149–0.6550 (Hu et al. 2013; Yu et al. 2017; Guo et al. 2020). However, in contrast to co-dominant markers, dominant markers tended to underestimate genetic diversity (Qian and Ge 2001), thus making comparison between level of genetic diversity in the present study using AhMITE markers with that in the previous studies using SSR markers difficult. But in the present study, it was still possible to assess genetic diversity of high-oleic peanut genotypes from representative breeding teams at gene, population and group levels.
In this study, of all the 8 populations, lines from CTW ranked first in genetic variability, followed by lines from C&Y, and cultivars from CTW occupied the third position. CTW team and C&Y team have succeeded in broadening the gene base in high-oleic peanut, as new lines from both teams had higher levels of genetic diversity. Over 90% of the total genetic diversity could be ascribed to within population diversity. Like the situation in the 8 populations, as shown by Gst of individual groups, for each group, within populations variation predominated (over 70% of total).
With the identification/creation of new high-oleic peanut mutants in CTW team (Nkuna et. 2021; Wang and Zhu 2017), more and more natural and induced mutants were used in breeding. Also, more exotic germplasm lines were used in hybridization in the development of these lines. These were the reasons why the lines from CTW team had the highest genetic diversity and why the lines and mutants from the team had a close relationship. Since all of the 3 cultivars from YRL used the same high-oleic peanut donor (Kaixuan 01–6) from JZG team (Wang and Zhu 2017), cultivars from YRL and JZG were also closely related.
To summarize, much variability resided within populations in this study. Of the high-oleic peanut cultivars, those from CTW team had the highest genetic variability. Of all the high-oleic peanut lines tested, those from CTW team ranked first in genetic diversity. As compared with high-oleic cultivars from CTW and C&Y teams, greater genetic diversity was detected in new lines of both teams, indicating that recent breeding efforts were effective in improving genetic diversity of high-oleic peanut.