학술논문
Genetic mapping of salt tolerance in rice using a novel association panel
Document Type
Electronic Thesis or Dissertation
Author
Source
Subject
Language
English
Abstract
Rice is an important crop in many countries. Salinity is a major abiotic stress which inhibits rice production. The aus rice have rich genetic diversity with wide variation in abiotic stress resistance. In this work, salt tolerance and sodium (Na+) and potassium (K+) accumulation were evaluated in the Bengal and Assam Aus Panel (BAAP, 266 out of 300 are aus rice) and quantitative trait loci (QTLs) and candidate genes were identified. Preliminary experiments were conducted to identify the suitable salt conditions for screening the large rice population. A salinity stress with 51.2 mM sodium chloride was selected as a screening method for subsequent experiments. Then salt tolerance at the rice seedling stage was evaluated in BAAP grown in both hydroponics and soil systems under control and salt stress conditions. Three cultivars, BRRI dhan 47, Goria, and T 1 showed more salt tolerance than the tolerant cultivar Pokkali in both systems. Genome-wide association (GWA) mapping was conducted on salt indices traits with 2 million SNPs using an efficient mixed model. A total of 97 and 74 QTLs associated with traits in hydroponic and soil systems were identified, respectively. A total of 65 candidate genes were found including a well-known gene OsHKT1;5. The information of the most significant QTL (Chromosome 1~ 40 Mb) was investigated. Two candidate genes OsSUMO1 and OsSUMO2 were found in this QTL region. The available data for the Na+ and K+ concentration in grains and shoots in the BAAP grown in field conditions under continuously flooded (CF) and alternate wetting and drying (AWD) irrigation were analysed. Overall, AWD significantly reduced the Na+ and increased the K+ in shoots and grains compared to the plants grown under CF. GWA mapping was conducted on Na+, K+ concentration and Na+/K+ ratio with 2 million SNPs and a total of 106 QTLs were identified. Four notable QTLs (one each on chromosomes 1 and 11, two on chromosome 2) and the haplotype variants of four candidate genes (OsHKT1;5, OsNHX2, LOC_Os02g32490 and OsFAD2_1) are discussed.