Genetic diversity and sex determination of jojoba genotypes using molecular markers

Abstract

Jojoba (Simmondsia chinensis) is an economically important species for arid and semi-arid regions, owing to its exceptional drought tolerance and the high commercial value of its seed oil. However, its dioecious reproductive system poses a major limitation for orchard establishment, as sex can only be distinguished after flowering. This process typically requires 3 to 5 years, after planting. In this study, molecular markers were employed to enable early sex identification and to assess the genetic diversity of jojoba genotypes. A total of 35 seed-derived genotypes from Antalya, Türkiye, were evaluated. Among three CAPS markers tested, the J900 primer provided clear and consistent polymorphisms, producing male-specific and female-specific fragments, with complete concordance with morphological observations. Sex determination revealed that 71% of the genotypes were female and 29% were male. For genetic diversity, 30 SSR primers were screened, of which six were polymorphic, generating 17 alleles with an average polymorphism rate of 70.6% and a mean PIC value of 0.72. Cluster analyses (UPGMA, NJ, and PCO) distinguished male and female genotypes and highlighted the genetic variability present within the population. These results demonstrate that the J900 CAPS marker is a reliable and efficient tool for sex determination at the juvenile stage, while SSR markers provide valuable insights into genetic structure. Collectively, the findings contribute to the development of improved breeding strategies and the establishment of high-yielding jojoba orchards.

Keywords

• Simmondsia chinensis
• Early sex determination
• SSR
• CAPS

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