MOLECULAR DIVERSITY OF STRESS TOLERANT RICE GENOTYPES USING SSR MARKERS

摘要

Genetic variability is the key for the development of new genotypes with desired combination of traits. Many times, the traditional donors for tolerance to stresses such as salinity look similar but differ in their response to the stresses. Molecular characterization of the genotypes gives precise information about the extent of genetic diversity which helps in the development of an appropriate breeding strategy. One hundred polymorphic SSR markers were used to characterize 21 rice genotypes. These genotypes comprised of nine salt tolerant genotypes including five Pokkali accessions. The materials also included two improved varieties with a major QTL for submergence (Subl) in Swarna background, i.e. IR82810-407 and IR82809-237. The rest were popular or moderately salt tolerant rice varieties of Bangladesh, India, International Rice Research Institute (IRRI), or Philippines origin. The highest number of alleles (12) were found for RM418 followed by RM 10793 (II), RM3412, RM400, and RM26809 (10). The highest PIC value (0.86) was found for RM 10793 followed by RM418 and RM3412 (0.85), RM26809, RM490 and RM287 (0.84), RM16 (0.83), RM493, RM562, and RM253 (0.82). These suggested their greater usefulness for characterizing rice varieties. Pokkali (Ace. No. 28609) and PSBRc82 were found to be the most genetically distant (78.65%) varieties. The Swama + Subl genotypes (IR82810-407 and IR82809-237) had the same genetic background; hence, they had highest genetic similarity between them (90%) and also with Swama (>70%). Two main distinct clusters/groups were identified from cluster analysis. One cluster consists of mostly improved and adapted genotypes while the second cluster had mostly salt tolerant donors with few exceptions. The study suggests the recombination strategy for the effective breeding program to enhance the level of salt tolerance and also to broaden the genetic base for wider adaptability.