Genetic diversity of eleven Moringa oleifera Lam. germplasm introduced to Yunnan, southwest China and their backgrounds during worldwide cultivation

Abstract

Moringa oleifera Lam. (synonym: M. ptreygosperma Gaertn.) is an economically important multi-purpose tree. It is indigenous to the sub-Himalayan tracts and has been widely introduced around the world. However, after a long history of cultivation, the genetic diversity/pool of some germplasms are unclear, which leads to uncertainty in designing breeding strategies. In order to explore the genetic backgrounds of M. oleifera introduced to Yunnan, southwest China, twenty previously developed species-specific SSR loci were used to investigate a total of 211 individuals of eleven germplasms introduced from India, Myanmar, Taiwan (southeast China), Kenya, Mali, the United States of America, and Cuba. The results showed that the germplasms introduced to Yunnan had different levels of genetic admixture. Four genetic groups were observed for which the genetic backgrounds of CU (Cuba), ND (New Delhi, northern India), PO (Pakokku, western Myanmar), US (the USA) and BL1 (Bangalore 1, southern India) were closely related and represented a genotype which was introduced to southern India and other areas of the world (i.e., Cuba, Myanmar, and the USA). Five germplasms have highly hybrid backgrounds. Which a genetic distance between germplasms from KE (Kenya, East Africa) and ML (Mali, West Africa) was very short, which were formerly introduced from Tanzania and South Africa, respectively, suggesting that the same genotype might have been widely introduced in Africa. We also found a different M. oleifera genotype from Sagaing (central Myanmar) that has not yet been studied genetically. In order to avoid homogenization and since the majority of these introduced germplasms have been spread worldwide and genetically admixed, we suggest that future studies should be conducted to incorporate correctly the newly confirmed genotype from Sagaing and avoid exogamic depression. Additionally, wild genotypes from the area of origin of this plant species should receive more attention in regards to preservation, breeding and cultivation.