Identification Of QTLs And Candidate Genes Associated With ABA Sensitivity In Common Wild Rice (Oryza Rufipogon Griff.)

Abscisic acid(ABA),as one of the foremost signaling molecules in plants,is an important hormone which plays versatile functions in regulating developmental processes and adaptive stress processes.Identification of QTL associated with ABA sensitivity would provide a useful basis for molecular breeding of stress tolerant in rice.In this study,a set of introgression lines,derived from the cross between Yuanjiang common wild rice(Oryza rufipogon Griff.)and an indica cultivar Teqing(Oryza sativa L.),were evaluated for the ABA sensitivity at the seedling stage.An introgression line YIL53,which showed sensitive to ABA,was characterized.Then we applied the map-based cloning strategy combined with gene expression analysis to candidate genes associated with ABA sensitivity from YIL53.The main results were as follows:1.Based on the observation of the introgression lines treated with 300 ?M ABA solution at the seedling stage,a total of 14 QTLs associated with ABA sensitivity were detected.The QTL qASS1-2 near the SSR marker RM212 on chromosome 1 exhibited obvious positive additive effect and showed the highest phenotypic variance(11%).2.An introgression line YIL53,which showed sensitive to ABA,was identified and characterized.Analysis of the physiological traits,including chlorophyll content,MDA content,soluble sugar content and stomata movement,showed that YIL53 was more injured than Teqing during ABA treatment,further revealing that the YIL53 was sensitive to ABA.Meanwhile,the analysis of the stress response showed that YIL53 was more susceptible to high temperature and drought stress than Teqing.3.The qASSI-2 was finally narrowed down to a 441 kb region between SSR marker RM212 and SNP marker M3 on the long arm of chromosome 1 using the segregation population derived from the cross between Teqing and YIL53.Furthermore,the expression profiles of YIL53 and Teqing under ABA treatment were obtained by Affymetrix rice whole genome array hybridization,and the results were confirmed by quantitative real-time PCR.By bioinformatics analysis and DNA sequence analysis,three genes(LOC_Os01g57450,LOC_Os01857560,LOC_Os01857770)in the mapping region related to ABA sensitivity were identified as the candidate genes.4.Transgenic plants of the RNAi and overexpression of the three candidate genes were obtained in order to confirm whether the ABA sensitivity of YIL53 was caused by the candidate genes.Comparing with the contrast plants,the overexpression,RNAi,and complementary transgenic plants of the candidate gene LOC_Os01g57450 showed no significant difference of ABA sensitivity.