Analysis of genetic diversity among some Iraqi durum wheat cultivars revealed by different molecular markers

TL;DR

This study used multiple molecular markers to assess genetic diversity and population structure among Iraqi durum wheat cultivars, revealing significant variability that can inform future breeding efforts.

Contribution

It is the first comprehensive analysis combining RAPD, ISSR, and CDDP markers to evaluate Iraqi durum wheat genetic diversity and population structure.

Findings

High polymorphism detected among cultivars

Most genetic variation exists within populations

Diverse genetic makeup supports breeding programs

Abstract

Durum wheat has been cultivated since the beginning of crop domestication, occupying now the tenth ranking among the global most significant cultivated crops. Despite the fact that, the extent of the crop genetic diversity has not yet fully incorporated into modern varieties through breeding programs. In this study, a total of 35 markers (11 RAPD, 12 ISSR, and 12 CDDP) were utilized to assess the genetic variability and population structure of sixteen different cultivars of Iraqi durum wheat. Out of 294 bands obtained, 171 were identified as polymorphic: 47.00 polymorphic alleles from 98 RAPD bands, 53 polymorphic alleles from a total of 89 ISSR bands, and 71 alleles from 107 CDDP bands. The average number of observed alleles (Na), effective number of alleles (Ne), Shannon's information index (I), expected heterozygosity or gene diversity (He), unbiased expected heterozygosity (uHe), and polymorphic information content (PIC) (1.45, 1.38, 0.32, 0.22, 0.24, and 0.28, respectively) were obtained for RAPDs , (1.63, 1.45, 0.40, 0.27, 0.29, and 0.32, respectively) ISSRs and (1.35, 1.35, 0.31, 0.21, 0.23, and 0.30, respectively) for the CDDP markers. A dendrogram of two main clades (unweighted pair group method with arithmetic mean; UPGMA) and three populations of structure analysis, were obtained based on the three markers data. The analysis of molecular variance indicated 97.00%, 97.00%, and 90.00% variability within populations, applying RAPD, ISSR, and CDDP markers, respectively. The highest diversity indices were revealed in population 2 under the RAPD and CDDP markers, whereas population 1 had the highest values of these indices according to the ISSR markers. The results provide greater knowledge on the genetic makeup of Iraqi durum wheat cultivars, that facilitate future breeding programs of this crop.