Genetic diversity associated with agronomic traits using microsatellite markers in Pakistani rice landraces
Genetic diversity underlies the improvement of crops by plant breeding. Land races of rice (Oryza sativa L.) can contain some valuable alleles not common in modern germplasm. The aim here was to measure genetic diversity and its effect on agronomic traits among rice land-race genotypes grown in Pakistan. Diversity was measured using thirty-five microsatellite markers and seventy-five genotypes. Among the markers used a total of 142 alleles were detected at 32 polymorphic SSR loci, while three loci were monomorphic in Pakistani rice landraces. The number of alleles identified by each marker ranged from 2 to 13 with a mean of 4.4. Size differences between the smallest and largest alleles varied from 11bp to 71bp. Polymorphism information content ranged from 0.124 to 0.836, with an average of 0.569. At nine microsatellite loci, basmati-type landraces amplified more different alleles than those in the coarse-type. DNA markers RM70 and RM72 divided the rice landraces on the basis of days to flowering. A dendrogram based on total microsatellite polymorphism grouped 75 genotypes into four major clusters at 0.40 similarity coefficient, differentiating tall, late maturing and slender aromatic types from the short, early and bold non-aromatic ones. It inferred that Pakistani landraces have diverse genetic bases and can be utilized in future breeding programs. The DNA markers developed will assist in genotype identification, purity testing and plant variety protection.