Genetic diversity analyzed by microsatellite markers among rice ( Oryza sativa L.) genotypes with different adaptations to saline soils

• Published in: Plant science (Limerick) 2004-05, Vol.166 (5), p.1275-1285
• Main Authors: Zeng, Linghe, Kwon, Taek-Ryoun, Liu, Xuan, Wilson, Clyde, Grieve, Catherine M., Gregorio, Glenn B.
• Format: Article
• Language: English
• Subjects: Adaptation to environment and cultivation conditions; Agronomy. Soil science and plant productions; Biological and medical sciences; cluster analysis; Fundamental and applied biological sciences. Psychology; genetic polymorphism; Genetic similarity; genetic variation; Genetics and breeding of economic plants; genotype; grain crops; Ion content; Ion selectivity; Microsatellite; microsatellite repeats; Oryza sativa; phenotypic variation; physiological response; plant adaptation; plant morphology; plant response; Rice; saline soils; salt stress; Salt tolerance; Varietal selection. Specialized plant breeding, plant breeding aims
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2004.01.005

The success of salt tolerance breeding programs employing traditional screening and selection has been limited in the past decades. This study was designed to characterize the genetic diversity within a subset of rice germplasm with different adaptations to saline soils using microsatellite markers. Salt tolerance was then analyzed among molecularly characterized genotypes. Plants of 33 genotypes were grown in sand tanks under greenhouse condition and irrigated with Yoshida nutrient solution. Two salt treatments were imposed with electrical conductivities of 0.9 dS m −1 (control) and 6.5 dS m −1 (6:1 molar ratio of NaCl and CaCl 2). A total of 123 alleles were generated at 25 microsatellite loci among the 33 genotypes. Genotypes of japonica rice grouped into three clusters and those of indica rice grouped into two clusters based on microsatellite markers. Thirty percent of the alleles detected in 20 breeding lines were not identified in the cultivars analyzed. These alleles may provide favorable allelic combinations if the breeding lines are used for intercrosses. Physiological and morphological characters under salt stress were significantly ( P=0.05) different among microsatellite clusters. There was a highly significant correlation ( r=−0.25; P=0.005) between the matrices of Jaccard genetic similarity based on microsatellite markers and taxonomic distance based on ion data. These results indicate that the adaptation of rice to saline soils is different among genotypes with diverse genetic backgrounds. Implications for engineering salt tolerance are: (1) Improving salt tolerance can be achieved by selecting parental genotypes prior to intercrossing based on microsatellite markers. (2) Phenotypic variation of ion contents in segregating populations can be increased by selecting parental genotypes prior to intercrossing based on microsatellite markers. (3) Different salt tolerance components can be combined into a cultivar by intercrossing genotypes from different microsatellite clusters with diverse salt tolerance mechanisms.