| Hybrid rice has played an important role in increasing rice yield,but the low yield of hybrid rice seed production is one of the main limiting factors affecting its further promotion.One of the key techniques in hybrid rice seed production is how to improve the outcrossing rate of female parent.Therefore,genetic improvement of stigma exsertion rate of male sterile lines is very important.Wild rice has outcrossing characteristics,and its stigma exsertion rate is generally high.Exploring the high exsertion rate genes of wild rice will provide an important material basis for improving stigma exsertion rate of CMS lines.The stigma of O.glumaepatula,which belongs to AA genome of cultivated rice,is large and exsertion rate is high.Exploring its high exsertion rate QTL will play an active role in genetic improvement of stigma exsertion rate of CMS lines.In this study,single-segment substitution lines(SSSLs)with O.glumaepatula as donors were used as basic materials to locate and aggregate QTLs Related to Stigma Exsertion Rate.The main results are as follows:1.Identification of QTLs related to stigma exsertion rate of O.glumaepatula.In the four seasons of 2017 and 2018,We planted 15 SSSLs and investigated stigma exsertion rate.After statistical analysis,10 QTLs were identified and distributed on chromosomes 1,2,3,5,6,9 and 10.the stigma exsertion rates of identified QTLs ranged from 42.07% to51.05%.with the addictive effect variation from 9.32% to 13.81%,and the percentage of additive effect variation from 39.78% to 58.95%.Compared with the previously identified QTLs,three new QTLs were identified in this study: q PES1-1,q PES1-2 and q PES10.2.For Fine Mapping the QTL q PES1-2 on chromsome 1 in the SSSL named “A143”,which have not previously been detected.nine homozygous secondary single-segment substitution lines were constructed by backcrossing A143 with recipient parent HJX74.by substitution fine-mapping system in the early and late seasons of 2018,The location of A143 was between RM403 and In Del-10 markers,within a physical distance of 2834.7 kb.q PES1-2 was mapped and localized between RM1095 and RM3411 markers,within a physical distance of 387.5 kb.3.the pyramiding effects and epistatic effects between QTLs related to stigmaexsertion rate of O.glumaepatula.In the early and late season of 2018,10 groups of polymorphic lines carrying paired QTLs related to stigma exsertion rate of O.glumaepatula were planted.The epistasis and aggregation effects were analyzed.The results showed that the interaction effect of each polymeric line was significant in 10 groups of QTLs.In the early and late seasons of 2018,the significant epistasis components accounted for 89.47%and 94.74% respectively.The additive epistasis and dominant epistasis effects were in the same direction,both of which were negative interaction,and the additive epistasis components were more common.The practicle polymerization effects were less than the theoretical polymerization effects.In the early season of 2018,the variation range of the practicle polymerization effects of homozygous double fragments from 19.59%(B71/A5)to 40.65%(B50/A5);In the late season of 2018,the variation range of the practicle polymerization effects of homozygous double fragments from 20.74%(B71/B9)to 31.95%(B50/A5);we have concluded that the percentage of exserted stigma of homozygous double fragments were mostly higher than phenotypic values of well SSSL parent and W0,The aggregation has achieved a certain cumulative effect among QTLs.In this study,On the basis of identification of the 10 QTLs related to stigma exsertion rate of O.glumaepatula,We have further Mapping the newly discovered QTL q PES1-2,We analyzed the aggregation and epistasis effects of 10 groups of QTLs related to stigma exsertion rate,and the cumulative effect and interaction rule were obtained.The results not only enrich the study on the excavation of good traits of O.glumaepatula,but also enrich the research on the location and pyramiding of QTL related to stigma exsertion rate. |
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