Evaluation of genetic diversity and structuration across altitude of walnut (Juglans regia L.) accessions from Morocco using SSR markers

Ghizlane Kabiri, Said Bouda and Abdelmajid Haddioui

Abstract: Evaluation of genetic diversity according to altitude level is becoming more and more important in the conservation and improvement programs. In this study, ten walnut accessions were sampled from different regions with different altitude level. By using SSR molecular marker, the genetic diversity and structure of walnut were analyzed. The results showed that the Moroccan walnut had high genetic diversity. The diversity within the accessions (Hs), total gene diversity (HT) and Shannon’s index (I) were 0.21, 033 and 0.49, respectively. Moreover, the total percentage of polymorphic loci (PPB) was 100% for all loci. Moreover, the variation in genetic diversity of all ten studied accessions indicated a great level of genetic diversity of accessions from low altitude (1000-1500) (HT = 31) than both very-low (500-1000) and moderate altitude (1500- 500) (HT = 0.25, HT = 0.29 respectively). AMOVA analysis showed that only 21% of the total genetic variation occurred among accessions, whereas 78% of the variance was within populations, this was in line with the high level of coefficient of genetic differentiation (GST = 0.37) and the low gene flow (Nm = 0.94). The Cluster and the Structure analyses results indicated that the ten walnut accessions were mainly grouped undependably to the geographic and altitude level into three groups. Based on the available data, it is likely that the altitude factor is enough to significantly influence the walnut genetic diversity, so this factor should be taken into consideration by the walnut crop breeders and users.

Keywords: altitude; genetic variation; SSR; walnut

Date published: 2022-06-15