水旱条件下小麦持绿相关性状QTL定位

QTL mapping of stay-green-related traits in wheat under drought condition

干旱是影响小麦生产中最重要的非生物胁迫。延长叶片持绿周期,进而增加光合时间,提高光合效率,对小麦在旱胁迫下保证有机物积累,最终达到小麦产量的稳定具有重要的意义。了解小麦旗叶持绿性保持的发育和遗传特征,并探索与小麦持绿基因密切相关且不受环境影响的稳定的分子标记,应用于育种可大大缩短抗旱育种周期。本研究以扬麦16和中麦895衍生的174个家系的DH群体为试验材料,通过设置正常滴灌(NI)和干旱胁迫(DS)处理,对2年2个水分处理下花后10 d、14 d、18 d、22 d、26 d和30 d旗叶绿色叶面积百分率(GLA)及叶绿素相对含量(SPAD值)进行表型测定,运用Gompertz模型模拟出GLA(%)变化趋势。将达到最大衰老速度的时间(TMRS)、绿色叶面积持续期(GLAD)、平均衰老速率(ARS)、旗叶快速衰老开始的时间(T1)、旗叶快速衰老结束的时间(T2)和旗叶动态SPAD值等11个持绿相关性状进行QTL定位。结果表明,水旱条件下,DH群体和亲本不同日龄下的GLA,衰老特征参数和旗叶动态SPAD值均存在超亲分离现象,并表现出一定差异。各家系和亲本不同日龄下的GLA均呈缓慢-快速-缓慢的动态下降趋势,快速衰老主要集中在18 d、22 d和26 d。除ARS和GLA-10D呈负相关,其余性状之间均呈现正相关。各性状遗传力范围在0.50~0.81之间。连锁分析在2个及以上环境中共鉴定到27个与小麦持绿相关的稳定位点,其中11个与小麦衰老特征参数相关,16个与旗叶动态SPAD值相关,分布在1A、1B、4B、4D、5D、7B和7D染色体上,分别解释表型变异3.86%~14.11%和2.99%~17.45%。在4B、4D和7B染色体上有1个调控T1和5个调控SPAD值的QTL在3个环境中被重复检测到,分别解释8.97%~14.11%和6.85%~17.45%的表型变异。QTL聚合效应分析发现,含有Rht-D1b和AA基因型的位点对SPAD-10D具有显著的增效作用和累加效应,含有GG和TT基因型的位点对SPAD-18D具有显著的增效作用和累加效应。在4B、4D、7B和7D染色体上发现了4个效应明显的QTL簇,位于4D染色体的QTL簇中存在不受水分环境影响的区段(18.80~28.58 Mb),该区段内包含Rht-D1基因,调控SPAD-0D和SPAD-10D的位点可能受到该基因的多效应影响。候选基因分析发现TraesCS4D01G054000、TraesCS1B01G434300和TraesCS7B01G010200等8个影响持绿相关性状的候选基因。以上研究结果为小麦持绿性分子标记辅助育种提供了理论依据。

Drought is the primary abiotic stress that significantly affects wheat production.Extending the duration of leaf green-ness,thereby increasing photosynthetic time and efficiency,is crucial for wheat in ensuring organic matter accumulation under drought stress and ultimately stabilizing wheat yield.Understanding the developmental and genetic characteristics of flag leaf greenness retention in wheat and identifying stable molecular markers closely associated with greenness-related genes,independent of environmental influences,can significantly accelerate the breeding process for drought resistance.In this study,we utilized a DH population consisting of 174 lines derived from Yangmai 16 and Zhongmai 895 as experimental materials.We conducted phenotypic evaluations of the percentage of green leaf area(GLA)and relative chlorophyll content(SPAD value)in flag leaves at 10 d,14 d,18 d,22 d,26 d,and 30 d post-flowering under two moisture environments:normal drip irrigation(NI)and drought stress(DS).We simulated the change in GLA using the Gompertz model and performed QTL mapping for eleven green-ness-related traits,including time to maximum senescence rate(TMRS),green leaf area duration(GLAD),average senescence rate(ARS),time to the beginning of rapid senescence(T1),time to the end of rapid senescence(T2),and the dynamic SPAD value of the flag leaf.The results revealed a phenomenon of transgressive segregation in GLA,aging characteristic parameters,and dynamic SPAD values of the DH population and parents under both well-watered and drought conditions,demonstrating cer-tain differences.A consistent trend of slow-rapid-slow decline in GLA was observed at different time points across all families and parents,with rapid senescence primarily occurring at 18 d,22 d,and 26 d Except for the negative correlation between ARS and GLA-10D,positive correlations were observed among all other traits.The heritability of each trait ranged from 0.50 to 0.81.Linkage analysis identified a total of 27 stable loci associated with greenness retention in wheat across two or more environments.Among these,11 loci were associated with wheat senescence characterization trait parameters,and 16 loci were associated with dynamic SPAD values of the flag leaf.These loci were distributed on chromosomes 1A,1B,4B,4D,5D,7B,and 7D,explaining 3.86%–14.11%and 2.99%–17.45%of the phenotypic variance,respectively.One QTL regulating T1 and five SPAD values on chromosomes 4B,4D,and 7B were consistently detected across the three environments,explaining 8.97%–14.11%and 6.85%–17.45%of the phenotypic variance,respectively.The results of QTL co-localization effect analysis revealed that loci containing Rht-D1b and AA genotypes exhibited significant enhancement and cumulative effects on SPAD-10D,while loci containing GG and TT genotypes showed significant enhancement and cumulative effects on SPAD-18D.Four QTL clusters with significant effects were identified on chromosomes 4B,4D,7B,and 7D.Notably,the segment of the QTL cluster on chromosome 4D(18.80–28.58 Mb)remained unaffected by water availability and contained the Rht-D1 gene.The loci regulating SPAD-0D and SPAD-10D might be influenced by the multiplicative effect of this gene.Candidate gene analysis identified eight candidate genes,such as TraesCS4D01G054000,TraesCS1B01G434300,and TraesCS7B01G010200,which are associated with greenness reten-tion.These findings provide a theoretical foundation for molecular marker-assisted breeding aimed at improving greenness retention in wheat.