Molecular and morphological characterization related to salt stress in natural populations of the Medicago polymorpha species

Abstract

Legumes are important crops due to their nutritional benefits as well as their utility in agriculture rotation. The morphological and molecular markers can elucidate plant response to stresses. In the present study, we investigated indicators of molecular polymorphism related to salt stress tolerance in natural populations of Medicago polymorpha species. The plant samples were collected from different geographical sites in western Algeria. Morphological growth parameters such as root length stem length of plant and T/R ratio were examined under four NaCl concentration levels (0, 68, 102 and 137 mM). The molecular study was carried out using SSR molecular markers on all the studied populations. Significant differences were observed in mean squares of analysis of variance, indicating relation between geographical origins and populations. This analysis showed the existence of two contrasted populations (DZ221 and DZ312). DZ221 is a relatively salt tolerant, and DZ312 is sensitive. The Principal Component Analysis (PCA) was calculated using the PCA function, revealing a high correlation between the morphological traits and the geographical distribution of populations. It divided populations into four distinguished groups respecting their origin geographical sites. The molecular results of the polymorphism degree showed that the natural populations of M. Polymorpha species were strictly homozygous (100%). The PIC index of the three microsatellites was very informative (0.77). Additionally, the results showed that both microsatellites (FMT11 and MTIC297) revealed some alleles detected in the tolerant population (DZ221) suggesting that they can be used as indicators of saline stress tolerance adaptation.