Association of Fruit and Seed Traits of Sapindus mukorossi Germplasm with Environmental Factors in Southern China

Sapindus mukorossi is widely distributed in tropical and subtropical areas of southern China; the seed kernel oil is potential biodiesel material, and the saponins extracted from fruit pericarp are very valuable efficient natural surfactants. Therefore, S. mukorossi is an ideal tree species for developing forestry bioenergy and multiple other products. In this study, 42 S. mukorossi fruits from mother trees were collected from 39 distinct locations in 12 Chinese provinces to infer fruit and seed trait responses to environmental factors. Canonical correspondence analysis (CCA) was conducted using 21 horticultural fruit traits and 10 environmental factors that represented different climatic and geographic conditions throughout southern China. CCA revealed well-developed patterns of natural phenotypic variation, and insight into the ecological factors that are potentially important in shaping this variation. The results presented here further elucidate the natural distribution and ecological adaptations of wild S. mukorossi resources, which will be valuable for S. mukorossi cultivation by helping identify ideal planting areas. The germplasm resources with extensive morphological variation can also contribute to S. mukorossi breeding in the future by helping develop new cultivars with high saponin yield.