Genetic diversity and structure of Tunisian and Indian date palm (Phoenix dactylifera and sylvestris) cultivars and genotypes revealed by AFLP markers

Abstract

The date palm breeding programs need to discover valid genetic fingerprints to characterize cultivars and assess their genetic diversity. This study assessed the genetic diversity among thirty-nine date palm cultivars from Tunisia ( Phoenix dactylifera ) and India ( Phoenix sylvestris ) by using six AFLP (Amplified Fragment Length Polymorphism) markers. 360 loci were amplified, with 127 loci polymorphic (34.35%). The Jaccard's similarity coefficient ranged from 0.161 to 0.931, with the mean genetic distances of 0.568. AFLP's average marker index value was 7.28, with a resolving power of 10.91. The analysis of population structure showed three main clusters with a clear separation between Tunisian and Indian cultivars. Furthermore, the heatmap analysis allowed the identification of 10 bands specific to the Indian accessions, which were not detected in Tunisian genotypes. These loci could be linked to genes involved in adapting the species in Indian lands, which allowed the study of the genetic diversity of date palm resources of different origins, confirming the existence of at least two origins of domestication. Additionally, identifying AFLP loci specific to P. dactylifera and P. sylvestris will significantly contribute to breeding programs by exploiting species-specific polymorphisms.