【作者】 李世平；

【导师】 王成社；

【作者基本信息】 西北农林科技大学 ， 作物遗传育种， 2013， 博士

【摘要】 小麦属喜凉习性作物，但生长季节内易受到异常高温造成的热胁迫影响，从而导致产量下降并且品质变劣。小麦籽粒灌浆形成的适宜温度为20-24℃，温度高于25℃，就会缩短灌浆时间，导致茎叶早衰，影响粒重的增长。从此意义上看小麦生产中的热胁迫影响可能是经常性的。小麦耐热性为复杂数量性状，开展小麦耐热相关性状的QTL定位分析和遗传剖析，对于小麦耐热分子育种有重要的现实意义。本研究以两个农艺性状差异较大的小麦品种旱选10号与鲁麦14杂交创建的加倍单倍体（DH）群体做为试验材料，考察幼苗期和灌浆期耐热相关性状，包括叶片持绿性状（CC）、叶绿素荧光参数（CFP）、根干重（RDW）、苗干重（SDW）及幼苗生物量（SB）叶片相对含水量（RWC）、冠气温差（CTD）、茎秆可溶性碳水化合物含量（WSC）及转运率（RE）、千粒重（TGW）等。对这些性状的耐热性（以耐热指数为耐热性指标）及性状的发育进行QTL定位分析，从分子水平上阐述了小麦耐热性的遗传基础和表达规律。（1）试验DH群体目标性状对高温反应敏感；群体中各株系呈现广泛变异和超亲分离，属于微效多基因控制的复杂数量性状。试验共检测到两个时期的不同性状耐热指数的31个加性效应QTL和39对上位性效应QTL；检测到耐热相关性状的118个加性效应QTL和149对上位性效应QTL，并分析了它们的遗传效应及其与环境的互作效应。（2）幼苗期检测到与幼苗性状耐热指数相关的5个加性遗传效应QTL和8对上位性遗传效应QTL；检测到控制幼苗耐热相关性状的8个加性遗传效应QTL和20对上位性遗传效应QTL。这些位点分布在除4D和6D染色体以外的19条染色体上。从QTL在染色体上的分布来看，控制幼苗耐热指数的QTL位点在6A、6B、3A、2D、5A和7A染色体上分布相对较多；而控制幼苗性状的遗传位点在2D、6B、3A、4A、5A和7A染色体上分布较多。幼苗耐热指数的遗传却以加性效应为主而幼苗性状的遗传以上位性效应为主。控制耐热指数的单个加性和单对上位性QTL所解释的表型变异范围分别为5.14%～12.41%和1.44%～3.61%；而控制幼苗性状的单个加性QTL和单对上位性效应QTL所解释的表型变异分别达0.32%～8.81%和0.71%～6.23%。（3）灌浆期检测到控制TGW、CC、RWC、CFP、CTD和颖壳、穗下节、其余茎秆可溶性碳水化合物含量（GWSC、NWSC和SWSC）的耐热指数26个加性效应QTL和31个上位性效应QTL；分别可解释表型变异的范围为2.64%～11.41%和0.99%～8.84%。耐热指数的遗传位点在1A、1B、2D、3A、5A、5B、6A、6B及7A等染色体上分布相对较多。其中有4个加性效应QTL的贡献率在10%以上。从遗传效应来看，TKW、CC、GWSC、NWSC和SWSC的耐热指数的遗传以加性效应为主，RWC、CFP、CTD的耐热指数遗传以上位性效应为主。颖壳可溶性碳水化合物含量的耐热指数与其它多数性状耐热指数显著正相关。（4）对苗期和灌浆期的耐热性QTL位点比较分析，幼苗期耐热指数的环境互作效应小，而灌浆期耐热指数的环境互作效应大。两个发育时期耐热性的遗传机制不太一致，但有一定的共同点，即携带它们的位点均在3A、6A和6B上的较多，遗传效应均以加性效应为主。两个时期的一些耐热性加性效应QTL定位在相同或相近位置，幼苗期生物量耐热指数QTL（Q.Sb.cgb-3D）与灌浆期千粒重耐热指数QTL（Q.Itgw.cgb-3D）均定位在3D染色体Xgwm456-Xgdm8区间距右标记1.8cM的位置；幼苗期叶绿素含量耐热指数QTL（QCc.cgb-2D.1）与灌浆期叶片相对含水量耐热指数QTL（Q.Itgw.cgb-2D）均定为在2D染色体P3176.1-P1123.1区间内。表明在小麦耐热性遗传上可能存在一些“永久性”表达基因，在整个小麦生育期均对小麦耐热性起调控作用。（5）灌浆期检测到三个测量时期的控制旗叶相对含水量和气冠温差的13个加性效应和26对上位性效应QTL，控制RWC的位点在染色体3B、5B和6A等上分布较多，控制NWC的位点在2B、2D、3B和3D等上分布较多，而控制CTD的位点在1B、2B、3B和5A上分布较多。3个性状3个时期的上位性效应及其环境互作效应较大，遗传基础复杂。检测到的控制胁迫7天时两种温度下自然含水量的遗传效应最多，可解释表型变异的64.5%。（6）灌浆期叶片叶绿素含量和叶绿素荧光参数对不同的环境条件反应比较敏感。小麦CC和CFP是微效多基因控制的复杂数量性状，易与温度及水分环境发生互作。共检测到该2性状在4环境3时期的21个加性效应和39个上位性效应QTL，控制CC的QTL主要分布在染色体1B、2D、4B、5A和6A上，控制CFP的QTL主要分布在1B、3A、3B和4A染色体上。检测到贡献率较高的3个加性QTL（Q.Ccu.cgb-1B.1、Q.Ccf.cgb-5A.1和Q.Ccf.cgb-2D），贡献率分别为19.40%、8.88%和7.39%。（7）灌浆期检测了DH群体中控制颖壳、穗下节和其余茎WSC含量及其转运效率的12个性状，这些性状均属于微效多基因控制的复杂数量性状。共检测到46个加性和25对上位性效应QTL，这些位点在1B、2A等染色体上分布较多。在7D染色体WMC436-Xgwm44上、2D的WMC170-Cwm96.2上和7A的P4114.1-P6934.2上检测到与WSC有关的重合位点，在2A、2D等上检测QTL簇。12个性状有10个以加性遗传效应为主。（8）利用不同的环境条件对小麦粒重进行了动态发育分析，共检测到30个加性QTL和39对上位性QTL，其位点在染色体1B、4B、2D、2A、7B、3B、4A和6A上分布较多。控制非条件下的粒重位点在染色体1B、3B、4B、7B等上较多，而控制条件下的粒重位点在染色体1B、2D、4A、4B等上比较多。在1B区段P3474-480-T122上，在2D的WMC453.1-WMC144上，在3B的Xgwm644.2-P2076-147上检测到控制粒重的QTL簇。粒重非条件遗传效应以加性效应为主，而条件遗传效应以上位性效应为主，条件和非条件下的环境互作效应均较小。并利用已知的全部DH群体的每个QTL基因型遗传效应的比较分析预测了QTL多位点最佳结合的优良等位基因型。更多还原

【Abstract】 The wheat (Triticum aestivum L.) belong to cool crop, and was affected by hightemperature during growing season, especially during later growing season. And the resulttended to drop grain yield and quality. The optimum temperature for grain filling was during20～24℃. When the temperature was above25℃, the time for grain filling will be shorten,the shoot will be premature senility and grain will be affected. From this sence, the impact ofthe wheat from high temperature is likely to be regular. Currently development of molecularquantitative genetics provided an effective method to study the genetic mechanism of heatresistance and its genetic patterns for complex quantitative traits. So, it is of very importancethat map QTLs and dissect genetic factors for complex quantitative traits associated with heattolerance in wheat molecular breeding of heat tolerance.Doubled haploid lines (DHLs) previously constructed by a cross between Hanxuan10andLumai14, two common wheat cultivars, being selected for experimental materials in presentstudy. Some of the important traits associated with heat-tolerance including content ofchlorophyll (CC), fluorescence parameter of chlorophyll (CFP), root dry weight (RDW),shoot dry weight (SDW), seedling biomass (SB) in different temperature during seedlingstage were investigated in different temperature. And flag leaf raletive water content (RWC),flag leaf natural water content (NWC), canopy temperature depression (CTD), glumewater-soluble carbohydrates (GWSC), neck stem water-soluble carbohydrates (NWSC) andthe rest stem water-soluble carbohydrates (SWSC), thousand-kernel weight (TKW), CC andCFP in grain filling stage were investigated in different temperature and water condition.Quantitative trait loci (QTL) mapping and QTLs×water environment interactions (QEIs) areanalyzed on these target traits in this study. The study mapped the QTLs for those traits andtheir heat tolerance index (HTI) and illustrated the genetic basis and expression regularpattern for heat tolerance of winter wheat.(1) All target traits from DHLs in the test showed significantly sensitive to heat stress andshowed wide variation and transgressive segregations, belonging to complicated quantitativetraits controlled by the tiny effect polygene and regulated by minor-effect polygenes whichwere easily affected by different environments. Total of31additive QTLs and39epistatic QTL of HTI for target traits and total of118additive QTLs and149epistatic QTL of thetarget traits were detected in two development period. And the genetic effect and theinteraction effect for QTL×environments were estimated and analyzed in this study.(2) The5additive QTLs and8epistatic QTL related to HTI of seedling traits, and8additive QTLs and20epistatic QTL related to seedling traits were located on allchromosomes except4D and6D under two temperature conditions. From the distribution ofthe QTLs detected by the test, the QTL for seedling traits mainly distributed on thechromosomes2D,6B,3A,4A,5A and7A, and that for HTIs mainly on the chromosomes6A,6B,3A,2D,5A and7A. The genetic effect of the QTLs for seedling traits mainly wasepistatic effect and their HTI mainly was additive effect. The phenotypic variance explainedby single additive QTL and single epistatic QTL controlling the HTI of seedling traits werefrom5.14%to12.41%and from1.44%to3.61%, respectively. And that for controllingseedling traits were from0.32%to8.81%and from0.71%to0.32%, respectively.(3) Total26additive QTLs and31epistatic QTLs for TKW, CC, CFP, RWC, CTD,GWSC, NWSC and SWSC in grain filling stage were detected on chromosome1A,1B,2D,3A,5A,5B,6A,6B,7A and so on. The phenotypic variance explained by single additiveQTL and single epistatic QTL for those QTLs were from2.64%to11.41%and from0.99%to8.84%, respectively. The genetic effect of4of the26additive QTLs were above10%. Thegenetic effect for HTLs of TKW, CC, GWSC, NWSC and SWSC mainly were additive effect,and that of RWC, CFP, CTD mainly were epistatic effect. The correlation coefficients amongthe HTI of GWSC with the most of other traits were highly significant.(4) The heat-resistance QTL of the DHL were compared and analysed in seedling stageand grain filling stage, and the result showed that interaction effect QTL×environment wererelatively small in seedling stage than in grain filling stage. The genetic mechanisms of theQTL for the two development stage were not very consistent, and there are some commonpoint bwtween them, that is the number of the QTL on6A，3A and6B were more in the twostage, and the additive effect was the main for those QTL. Some of the additive QTL in thetwo stage were detected on the same or close site. For instance, both of the QTL(Q.Sb.cgb-3D) for HTI of SB in seedling stage and the QTL (Q.Itgw.cgb-3D) for HTI ofhousand-kernel weight (TKW) in grain filling stage were deteced at the place1.8cM from theright mark between Xgwm456-Xgdm8on3D. And both of the QTL (QCc.cgb-2D.1) for HTIof CC in seedling stage and the QTL (Q.Itgw.cgb-2D) for HTI of RWC in grain filling stagewere deteced between P3176.1-P1123.1. This suggested that there may be some "permanent"expressed genes for the genetic of heat tolerance in wheat, and they play the regulatory rolefor heat tolerance in the whole growth period. (5) Total13additive and26epistatic QTL for RWC, NWC and CTD between differentheat stress time were detected in grain filling stage. And the QTLs for RWC mainlydistributed on chromosome2B,3B,5B,6A, and the QTLs for NWC mainly on2B,3B and3Dand the QTLs for CTD mainly on1B,2B and3B. The genetic effect of the epistatic QTLs andepistatic QTLs×environment were larger than additive QTLs. The genetic effects for NWCunder heat-stress for7days was the most, and the contribution for phenotypic variation was64.5%.(6) CC and CFP were sensitive to temperature environment condition and may be usedas parameter for heat tolerance in grain filling stage. They essentially were subjected to thecomplex quantitative traits regulated by minor-effect polygenes which were easily affected bydifferent environments. Total of21additive and39epistatic QTL for CC and CFP weredetected. The QTLs for CC mainly distributed on chromosome1B,2D,4B,5A and6A, andthat for CC mainly on chromosome1B,3A,3B and4A. Three QTLs (Q.Ccu.cgb-1B.1,Q.Ccf.cgb-5A.1and Q.Ccf.cgb-2D) had large contribution were detected in the test, and theircontribute for phenotypic variation were19.40%,8.88%and7.39%, respectively.(7) The12traits for GWSC, NWSC, SWSC and their remobilization were detected in grainfilling stage, and all of them belong to complex quantitative traits regulated by minor-effectpolygenes. Total of46additive and25epistatic QTL for target traits were detected, and mostof them on chromosome1B,2A,2Dand so on. Some of the QTLs for the three traits wereshared the same intervals, that is, C436-Xgwm44on7D, WMC170-Cwm96.2on2D andP4114.1-P6934.2on7A. The QTL clusters were detected on chromosome2A,2D,3A,3D,7A and7D. The genetic effect of the targets traits mainly were additive effect.(8) Total of30additive and39epistatic QTLs for grain weight developmental behaviourwith unconditional and conditional method were detected, and mainly distributed onchromosome1B,4B,2D,2A,7B,3B,4A and6A. The locus for unconditional grain weightmainly distributed on chromosome1B,3B,4B and7B, and that for conditional grain weightmainly distributed on chromosome1B、2D、4A and4B. The QTL clesters were detected onthe intervals of P3474-480-T122on1B, WMC453.1-WMC144on2D, Xgwm644.2-P2076-147on3B. The genetic effect for unconditional grain weight mainly wereadditive effect, and that for conditional grain weight mainly were epistatic effect. The effectof QTL×environment with unconditional and conditional method were minor. The testpredicted superior alleles constituted with the superior polygene by the total genetic effects ofknown QTL from individual DHLs.更多还原