The response of rice mutant lines to salinity stress at seedling stage using morphological traits and microsatellite markers

Salinity stress is the second major problem and limiting the rice production after drought. To investigate the effects of salinity stress on some important morphological and physiological characteristics of rice, 41 mutant lines from radiation of gama ray to four rice varieties (two Iranian local varieties, Hashemi and Tarom and two improved varieties, Khazar and Fajr) along with parental varieties and two control lines, FL478 (tolerant to salinity) and Teqing (sensitive to salinity) were studied under three salinity conditions (control, 6 and 12 dS.m-1). The experiment was carried out in factorial experiment based on completely randomized design with six replications. The variation among genotypes were also studied using twelve microsatellite (SSR) markers linked to SalTol, a major salinity tolerant QTL. The results of analysis of variance showed significant and considerable differences among the genotypes for all studied traits. The results of cluster analysis of morphological data grouped the studied genotypes into three clusters so that M1, M3, M7, M9, M35, M37 and M40 mutant lines together with the salinity tolerant line FL478 grouped into one cluster, while Hashemi and Fajr varieties and M47, M48, M49 and M56 mutant lines along with the salinity sensitive line Teqqing grouped into a similar cluster. The cluster analysis of molecular data also divided the studied genotypes into three main groups. Accordingly, the mutant lines M35, M37 and M40 together with the control variety FL478 were grouped as salinity tolerant and the mutant lines M36, M47, M48, M49, M54 and M56 together with the control variety Teqing as salinity sensitive genotypes. The Mantel test showed a high similarity of about 65%between two cluster analyses which was due to the use of tigh linked SSR markers to the SalTol, each of them were linked to the several traits studied in this research. As mentioned above, all three salinity tolerant lines identified in the molecular data analysis were also identified in cluster analysis of morphological traits and all four salinity sensitive lines identified in the morphological data analysis were also identified in molecular dataanalysis. Evaluating the microsatellite markers also showed that the AP3206, RM5, RM3412, RM140 markers were the most suitable and informative markers to assess the genetic variation of salinity tolarance in this research.