| It's important to evaluate rice germplasm resources and develop elite rice varieties with high seed storability for seed production and national food security.In this study,uising 18 indica and japonica rice,as well as one doubled haploid(DH)population derived from Fi of indica TN1 and japonica CJ06,the physiological index related to seed storability were conducted,quantitative trait loci(QTLs)for seed storability were identified,and the new rice lines with high seed storability were developed by molecular assisted selection(MAS)method.These results will provide the basis for the in-depth study on the characteristics and mechanism of seed storability in rice,and will benefit to the development of new rice varieties with high seed storability and then promote the development of seed industry.The main results were as follows:1.Three varieties including ZhongXuan No.2 with relative higher seed storability and four varieties including Changjingxiang with relative lower seed storability were identified though natural and artificial aging methods among 18 rice varieties derived from different regions.There were significantly negative relationships between seed germination rate and the contents of total soluble sugar,sucrose and fatty acid in dry grains under natural and artificial aging conditions,respectively,while it was no significantly correlated with the contents of fructose and glutenin.Seed artificial aging index was significantly and positively correlated with sucrose content in dry grains.During seed germination,total soluble sugar content increased firstly and then accelerated,then decreased slowly;the contents of sucrose and fructose was slightly increased and then decreased,but the change range was small.The fatty acid content increased gradually.Meanwhile,there were significant and negative relationships between seed germination percentage with the contents of total soluble sugar,sucrose and fatty acid in germinating grains under natural and artificial aging conditions,respectively,while seed natural and artificial index were significantly and positively correlated with the contents of total soluble sugar,sucrose and fatty acid.These results indicated that there was a close correlation between seed storability and sugar contents in rice grains.There was significant and positive correlation between natural and artificial aging methods,which indicated that the study of seed storability can be conducted by artificial aging method in rice.2.QTLs for the contents of total soluble sugar,sucrose and fructose in dry grains were detected using one DH population with 120 lines derived from indica TN1 and japo,nica CJ06.A total of 17 QTLs conferring sugar contents were detected on chromosome I,3,4,5,6 and 8,respectively.Among them,four QTLs for total soluble sugar content were identified;the value of LOD ranged from 2.49 to 3.64,and each QTL can explain 7.2%to 15.8%of phenotypic variation.Seven QTLs for sucrose content were identified;the value of LOD ranged from 2.62 to 3.83,and each QTL can explain 6.1%to 14.4%of phenotypic variation.Six QTLs for fructose content were identified;the value of LOD ranged from 2.39 to 3.42 and each QTL can explain 7.5%to 15.0%of phenotypic variation.Meanwhile,one epistatic QTL for total soluble sugar content was identified,locating on RM1195-RM575 of chromosome 1 and RM331-RM3395 of chromosome 8,which can explain 12.0%of phenotypic variation.Two epistatic QTLs for fructose content were identified,locating on RM104-RM1067 of chromosome 1 and RM1235-RM1376 of chromosome 8,and RM252-RM3276 of chromosome 4 and RM418-RM11 of chromosome 7,respectively,and these two epistatic QTLs can explain 10.6%and 9.0%of phenotypic variation respectively.17 QTLs conferring sugar contents were colocated on nine chromosome regions,and 5 QTLs were near to the location of starch synthesis genes reported previously.3.Using the same DH population with 120 lines derived from indica TN1 and japonica CJ06,QTLs for seed storability were identified under natural and atrifical aging conditions.A total of 6 and 5 QTLs for germination percentage and fatty acid content were detected under natural aging condition,respectively,while 4 and 5 QTLs for germination percentage and fatty acid content were detected under artificial aging condition.These QTLs were located on chromosome 1,2,3,4,6,8,9,11 and 12 respectively.Each QTL can explain 2.1%to 22.7%of phenotypic variation for germination percentage,and 2.5%to 15.1%of phenotypic variation for fatty acid content.Meanwhile,4 and 2 epistatic QTLs for germination percentage and fatty acid content were detected under natural aging condition,respectively,while 2 and 1 epistatic QTLs for germination percentage and fatty acid content were detected under artificial aging condition.Each epistatic QTL can explain 2.39%to 10.88%of phenotypic variation for gemination percentage,and 4.21%to 7.97%of phenotypic variation for fatty acid content.The QTL qGP-9 for germination percentage,located on RM7364-RM3700 of chromosome 9,was simultaneously detected under both conditions.qGP-9 was collocated with the location of QTL qFA-9 for fatty acid content,suggesting it might be a major QTL for seed storability.Using near-isogenic lines,qGP-9 was further fine mapped to the region between molecular marker P6 and P8 with 92.8 kb physical distance,in which 15 open reading frames were predicted.4.The seed storability gene qGP-9 was trogressed into japonica TM1 using rice variety ZX2 as donor with qGP-9 though MAS and conventional breeding techniques.Five lines FM-1,FM-2,FM-3,FM-4 and FM-5 were developed with qGP-9 of donor ZX2,and these lines had excellent agronomic traits.Based on the trait of aging index under artifical aging condition,the seed storability of those 5 lines was significantly improved compared to the recurrent parent TM1.Meanwhile,those 5 lines had similar plant architecture,plant height and heading date with the recurrent parent TM1,and the yield of four lines FM-1,FM-2,FM-3 and FM-4 was significantly increased compared to TM1. |
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