ارزيابي تنوع ژنتيكي ژرم پلاسم برنج ايراني براي تحمل به شوري و مكان يابي QTL هاي مرتبط با آن

چكيده انگليسي :

Evaluation of Genetic Variation in Iranian Rice Germplasm for Salt Tolerance and Mapping QTLs for Related Traits AbstractThe evaluation of Iranian rice germplasm for salt tolerance and mapping of the related QTLs wereperformed in four experiments In the first experiment the response of 75 rice cultivars includingIranian landraces improved and introduced cultivars to salt stress was studied at seedling stage in afactorial trail in randomized complete block design with three replications Cultivars were evaluatedat normal condition 1 2 dS m 1 and two salinity 4 and 8 dS m 1 of NaCl levels Significantdifferences were detected among cultivars and between salinity levels for all the studied traits Rootand shoot length and dry weights biomass and K percentage were reduced as the salinity levelincreased to 8 dS m 1 but Na percentage and Na K ratio were increased Genotypic code hadsignificant negative correlations with shoot dry weight and biomass but significant positivecorrelations with Na concentration and Na K ratio in 4 and 8 dS m 1 salinity levels In 4 dS m 1salinity level shoot dry weight had a high direct effect on genotypic code In 8 dS m 1 salinity level high positive and negative direct effect on genotypic code were found for biomass and Na concentration respectively Stepwise regression analysis indicated the importance of biomass shootdry weight and K concentration in determination of genotypic code variability Cluster analysisgrouped the cultivars in salt tolerant sensitive and intermediate classes In the second experiment biomass variation was studied in greenhouse at normal condition 1 2 dS m 1 and two salinity 4 and8 dS m 1 of NaCl levels Significant differences were found among genotypes and between salinitylevels for biomass at vegetative growth stage In the third experiment 65 rice cultivars were evaluatedfor agronomic traits yield and yield components in a saline field located near the Someasara city Grain yield had significant and positive correlations with seed weight plant No of plant m2 plantheight panicle length and biomass at 4 and 8 dS m 1salinity levels from the second experiment Stepwise regression revealed the importance of seed weight plant and No of plant m2 in grain yieldvariability In the fourth experiment two tolerant and sensitive cultivars Tarommahalli and Khazar respectively were selected based on the result of previous experiments and crossed to produce the F2population for QTL mapping Linkage map based on SSR markers was derived using 74 polymorphicmarkers in 12 linkage groups in parents and 192 F2 individuals This map covered 1231 5 cM of thegenome The phenotypic values were collected from 192 F3 families based on Gregorio et al and Linet al procedures qSTR 6 qSTR 3a genetypic code qDWS 3 qDWS 8 shoot dry weight qNA 2a Na concentration and qK 5a K concentration explained 12 7 to 20 9 of phenotypic variabilitiesand considered as major QTLs Based on the results obtained the alleles in a region on chromosome3 between RM6832 and RM7389 act to increase salt tolerance through reduction of Na K ratio genotypic code and Na concentration and increase of shoot dry weight Since qSTR 3b qNA 3 andqNAK 3 explained 13 07 10 92 and 9 03 percentages of genotypic code Na concentration andNa K ratio variabilities respectively this region could be considered as a good candidate to selectthe best genotypes in marker based selection method qNT 7 with likelihood ratio of 15 81 had amajor effect on No of panicle plant and explained 20 57 of its phenotypic variability The allelefrom Tarommahalli parent increased No of panicle plant The dominance effects of all alleles expectthe alleles of qNT 5 reduced No of panicle plant Plant height QTLs were located on chromosome 1and the allele from Tarommahalli at qHI 1a increased plant height For No of filled grain plant onlyone QTL was located on chromosome 3 and its alleles from Tarommahalli increased No ofseed plant

صبوري، حسين

ارزيابي تنوع ژنتيكي ژرم پلاسم برنج ايراني براي تحمل به شوري و مكان يابي QTL هاي مرتبط با آن

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