| Grain quality is one of the most important breeding objective in rice breeding.Much progress has been made in the past two decades in understanding the molecular basis behind different quality traits.In the present research work with using DH population,we detected quantitative traits loci(QTLs)related to rice grain quality.The main focus of this study were to identify novel and important QTLs that could be stable in different environmental conditions which in turn will affect quality traits of the rice grain.To determine the rice physiochemical and nutritional properties of rice grain,the genetic linkage map of a DH population which derived from Zhongjiazao 17,a super rice variety,crossed with tropic Japonica variety D50 was constructed,then the experiments were conducted in three planting seasons,Hangzhou 2016,Hangzhou 2017,in Zhejiang province and Lingshui 2017,in Hainan province.A genetic linkage map contains 12 linkage groups with a total length of 1215.2 cM was constructed using 170 SSR markers,the genetic distance of adjacent markers ranges from 0.5 cM to 26.9 cM and the average is 7.1 cM.The QTLs were determined by using Windows QTL Cartographer Version 2.5(Win QTLCart 2.5)with the composite interval mapping(CIM)function and a LOD value of 2.5 was set as the threshold for detection of putative QTLs.QTLs with epistatic effects and QTL-by-environment interaction(QEs)effects were analyzed using QTL Network-2.1 with the mixed-model-based composite interval mapping(MCIM).The mainly conclusions were list as following:1.To determine the genetic basis of the paste viscosity attributes to rice grain,quantitative trait loci(QTLs)associated to RVA profile properties were mapped.The 54 QTLs were located on all the 12 chromosomes,with single QTL explaining 5.99 % to 47.11 % of phenotypic variation.From the QTLs identified,four were repeatedly detected under three environmental conditions and the other four QTLs were repeated under two environments.Most of the QTLs detected for peak viscosity(PKV),trough viscosity(TV),cool paste viscosity(CPV),breakdown viscosity(BDV),setback viscosity(SBV),peak time(PeT)were located in the interval of RM6775-RM3805 on chromosome 6 under all the three environmental conditions,except pasting temperature(PaT).For digenic interactions,total of 8 QTLs with 6 traits were identified for additive × environment interactions in all three planting environments.The epistatic interactions were estimated only for PKV,SBV,and PaT.2.To analyze the QTLs for Apparent Amylose content(AAC)and Gelatinization temperature(GT).A sum of 45 main effect QTLs,including 39 for DSC,and 6 QTLs for AAC content were identified under three planting seasons.The 45 QTLs were located on all chromosomes with single QTL explaining 6.32 % to 25.70 % of phenotypic variation,except chromosome 8 and 12,respectively.The positive correlation was found between DSC parameters and with AAC,while the negative correlation was observed with ?H and AAC in all three environments.The major gene is the alk gene on chromosome 6 were identified for qTp-6 in E1 and E2,qTc-6 in E1,E2,and E3,q?H-6 in E2 and qAC-6 in E1.In the present study several QTLs with important effects on the variations in the measured parameters but some QTLs,qTo-7,qTp-3,qTp-7,qTc-7 and q?H-3 in the marker intervals RM15490-RM3601 and RM234-RM118 on chromosome 3,7 were stability detected in each of three environments,which have not been found in earlier reports based on populations derived from parents with different AAC and Wx alleles.Eight pairs of repeated QTLs qTo-7,qTp-3,qTp-4,qTp-6,qTc-6,qT c-7,q?H-3,and qAC-2 co-localized on chromosomes 2,3,4,6,and 7,respectively.For all of these pairs,the mostly additive effects came from D-50 Japonica parent.In addition,three QTLs for additive x environment interaction and three pairs of epistatic QTLs,Endset(Tc),Enthalpy(?H),and AAC were identified.3.QTL analysis for the contents of protein and metal elements in brown rice,totally 55 QTLs were detected,for HZ-16 total 24 QTLs,16 QTLs for HZ-17 and 15 for HN-17 were identified.These QTLs distributed on all the 12 chromosomes except chromosome 4 and 6,among these QTLs,qCu-1a had the largest single effect(38.99 % of the phenotypic variance),and qCd-3 had the lowest single effect(4.01 % phenotypic variation).The positive alleles derived from D-50 allele(increasing trace metal element concentrations)at 33 QTLs and other QTLs were inherited from YK17.In addition,we found some stable loci and several QTL clusters for multiple metal elements and PC,which were stable under all three environmental conditions,harbored QTL with marker intervals,qCd-1 with RM1329-RM10316 on chromosome 1,qCu-1 with RM3148-RM10316,qZn-1 with RM7075-RM7405,qPC-1 with RM3148-RM10316 and qPC-3 with RM15844-RM1373,respectively.Simple correlation results clearly show that there are positive correlations among different micronutrients elements and PC,but non-significant correlation between Cd with Fe and PC.While,Cu with Fe,Zn with Mn,and Fe with Mn and PC.However,Fe and Zn were strongly positively correlated irrespective of the seasons,locations,and populations.Eight QTLs(qCd-10,qCu-1a,qCu-1b,qZn-11,qMn-7,qMn-8,qPC-1 and qPC-3)for five traits Cd,Cu,Zn,Mn and PC were mapped with additive x environment interaction in all three environments,except Fe.The additive x environment interaction of all traits were non-significant and the phenotypic contribution rate of these QTLs were also less than their main effect QTLs,it revealed that these QTLs are stable in all environments and have no environmental effect.These QTLs in the DH population can be applied in rice breeding for fine map molecular mechanisms underlying these traits await further elucidation for the improvement of physico-chemical and nutritional quality of rice. |
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