Drought-tolerance QTLs commonly detected in two sets of reciprocal introgression lines in rice

Abstract

Abstract. Drought is one of the major abiotic stresses limiting rice (Oryza sativa L.) production. Quantitative trait loci (QTLs) for drought tolerance (DT) at the reproductive stage were identified with two sets of reciprocal introgression lines derived from Lemont  Teqing. In total, 29 and 23 QTLs were identified in the Teqing and Lemont backgrounds, respectively, during the reproductive stage under drought and irrigated conditions for spikelet number per panicle, seed fertility, filled grain weight per panicle, plant height, and grain yield per plant. Most of these QTLs showed obvious differential expressions in response to drought stress. Another 21 QTLs were detected by the ratio of trait values under drought stress relative to the normal irrigation conditions in the two backgrounds. For 28 DT QTLs, the Teqing alleles at 23 loci had increased trait values and could improve DT under drought stress. Only five (17.9%) DT QTLs (QSnp1b, QSnp3a, QSnp11, QSf8, and QGyp2a) were consistently detected in the two backgrounds, clearly suggesting overwhelming genetic background effects on QTL detection for DT. Seven of the DT QTL regions identified were found to share the same genomic regions with previously reported DT-related genes. Introgressing or pyramiding of favourable alleles from Teqing at the validated QTLs (QSnp3a, QSnp11 and QGyp2a) into Lemont background may improve DT level of Lemont.

Detecting major QTL associated with resistance to bacterial blight using a set of rice reciprocal introgression lines with high density SNP markers

“…In this study, we found that only four (57.1%) of the seven QTL for Xoo pathotypes CII and CIV were detected in both backgrounds, meaning that some QTL were detected in one background and not in the other. This indicated that there also existed a GB effect on the expression of the QTL's resistance to BB, which was consistent with the GB effect on QTL associated with resistance to sheath blight (Xie et al 2008), abiotic stress tolerance (Cheng et al 2011, Wang et al 2014a, and yield related traits in rice (Mei et al 2006, Wang et al 2014a, Wang et al 2014b) detected in the reciprocal ILs derived from the same parents, Lemont and Teqing. Interestingly, the direction of the additive effect was consistent for the QTL detected in both ILs, confirming that the GB can influence the QTL effect but without affecting the direction (Liao et al 2001, Mei et al 2006, Xie et al 2008, Yang et al 2009, Zheng et al 2011.…”

“…, Wang et al. ) detected in the reciprocal ILs derived from the same parents, Lemont and Teqing. Interestingly, the direction of the additive effect was consistent for the QTL detected in both ILs, confirming that the GB can influence the QTL effect but without affecting the direction (Liao et al.…”

“…Most of the ILs were recovered to the recurrent parents. The genomes of the recurrent parent accounted for an average of 87.29%, ranging from 26.17% to 99.96%, in LT-ILs, and an average of 91.93%, ranging from 61.27 to 99.99%, in TQ-ILs (Wang et al 2014a, Wang et al 2014b). An inoculum of each race was prepared by suspending the bacterial mass in sterile water at a concentration of 108 cells/mL.…”

“…An array contained 9000 SNP markers evenly distributed on 12 chromosomes (Chen et al 2014) was used to genotype 192 LT-ILs, 218 TQ-ILs and the two parents, Lemont and Teqing. A total of 3924 polymorphic SNPs were available (Wang et al 2014a, Wang et al 2014b, which were evenly distributed on the 12 chromosomes, covering an average of 96.58% (369.1 Mb) of the whole rice genome published by the International Rice Genome Sequencing Project (2005). Chromosomal coverage ranged from 90.94% on chromosome 11 to 99.53% on chromosome 8 (Table S1).…”

Scanning QTLs for Grain Shape using Two Sets of Introgression Lines in Rice

“…The QTL effects in different backgrounds were diverse when different recipient parents were used (Yousef and Juvik, 2002). It was reported that below twenty percent of the QTLs for yield and related traits, resistance to biotic and abiotic stresses were detected in reciprocal ILs (Mei et al, 2006;Xie et al, 2008;Cheng et al, 2012;Wang et al, 2014). Till now, very little researches reported genetic background effect on QTL expression for grain shape, and very few QTL for grain shape independent from genetic background was identified.…”