Morphological, SSR and ISSR marker based genetic diversity assessment of mountain papaya germplasm in comparison with Carica papaya

Abstract

The genetic diversity in papaya cultivars is essentially important as it provides the basis for varietal improvement. In this regard a study was initiated to assess the genetic diversity of the commercial Carica papaya cultivars in Sri Lanka and to introduce mountain papaya (Vasconcellea cundinamarcensis), which is reported to contain cold resistance and papaya ring spot virus (PRSV-P) resistant trait. Twenty one accessions of Carica papaya and mountain papaya were assessed by morphological, simple sequence repeat (SSR) and inter simple sequence repeat (ISSR) markers. A total of 33 alleles were generated with an average frequency of 2.5 alleles per marker from 11 SSR and 2 ISSR markers. Morphological and molecular marker based cluster analyses revealed that there was no clear distinction among the C. papaya cultivars grown in different geographical areas in Sri Lanka, while mountain papaya was highly distinct from the other C. papaya accessions. Except three SSR markers, all the other markers were polymorphic between mountain papaya and C. papaya accessions. Of the 33 alleles produced, 12 alleles were common for both C. papaya and mountain papaya indicating the potential relatedness to C. papaya. This investigation revealed both the genetic diversity and the relatedness of mountain papaya with C. papaya so as to use it as a potential source for the improvement of C. papaya by hybridisation.