小麦灌浆期耐热性QTL定位分析

Mapping QTL for Heat Tolerance at Grain Filling Stage in Common Wheat

【目的】以普通小麦加倍单倍体(DH)群体(旱选10号×鲁麦14)的150个株系为材料,鉴定其灌浆期耐热相关生理性状及千粒重耐热指数,并进行QTL定位,以期发掘具有显著效应以及不同环境中稳定表达的主效QTL,为改良小麦耐热性提供理论依据及分子标记。【方法】运用基于混合线性模型的复合区间作图法,以耐热指数为耐热性指标,对DH群体在田间雨养和灌溉2种土壤水分条件下的耐热性进行QTL定位。【结果】2种土壤水分条件下共检测到12个控制不同性状耐热指数的加性效应QTL,对表型变异的贡献率范围为2.64%—11.41%,其中,9个QTL与环境存在互作效应,对耐热指数表型变异的贡献率为1.41%—4.66%;检测到17对上位性效应QTL,对表型变异的贡献率为2.45%—8.84%,其中,仅4对与环境有互作效应,对表型变异的贡献率为0.62%—2.32%。控制耐热性的QTL来自双亲,DH群体中有耐热性超亲的株系存在。【结论】评价小麦灌浆期的耐热性,千粒重耐热指数是最直接的指标,生理性状指标为耐热性鉴定的间接辅助指标,其中,旱地条件下选用旗叶相对含水量耐热指数作为间接指标较好,而灌溉条件下选用气冠温差耐热指数较好。染色体1B、2D、5A、5B、6A、6B和7A对灌浆期耐热性贡献较大。千粒重耐热指数和旗叶叶绿素含量耐热指数的遗传以加性效应为主,叶绿素荧光参数耐热指数和气冠温差耐热指数的遗传以上位性效应为主,而叶片相对含水量耐热指数的遗传加性效应与上位性效应都重要。

【Objective】In this study,a doubled haploid（DH） population with 150 lines,which was derived from the cross of two Chinese common wheat cultivars Hanxuan 10 and Lumai 14,was used as the plant material to identify the heat tolerance index（HTI） for related physiological traits and thousand-grain weight（TGW） at grain filling stage in common wheat and carry out quantitative trait loci（QTL） analysis.The purpose was to identify the essential QTL with stable and remarkable effects and find a theoretical basis on marker-assisted selection for improving the heat tolerance in wheat breeding program.【Method】 The mixed-model-based composite interval mapping method was employed to identify QTL for HTI of related traits in two soil moisture environments.【Result】A total of 12 additive QTL and 17 epistatic QTL for HTI of TGW and physiological traits related to heat tolerance were located on all chromosomes except 1D,6D and 7B under two soil moisture conditions.One single additive QTL can explain 2.64%-11.41% phenotypic variance for HTI,and a pair of epistatic QTL can explain 2.45%-8.84% phenotypic variance for HTI.Nine of 12 additive QTL have interaction effects with the environments,and the interaction effect of single additive QTL with the environment can explain 1.41%-4.66% phenotypic variance for HTI.Only 5 of the 17 epistatic QTL exist interaction effects with the environments,and the interaction effect of single pair of QTL with the environment can explain 0.62%-2.32% phenotypic variance for HTI.The allelic contribution to the HTI QTL came from both parents.Some DH lines were more tolerant to the heat stress than their parents.【Conclusion】 To evaluate the heat tolerance at grain filling stage,the HTI for TGW is a direct criteria,the following two physiological index are indirect criteria,i.e.the HTI for flag leaves relative water content（IRWC） is an available index under rainfed condition,and the HTI for canopy temperature depression（ICTD） is suitable under well-watered condition.The QTL for HTIs mainly distribute on the chromosomes 1B,2D,5A,5B,6A,6B and 7A,showing that these chromosomes have close relationship with heat-tolerance at grain filling stage.The genetic effects of QTL for TGW HTI and chlorophyll content（CC） mainly are additive effect,and that of CTD and chlorophyll fluorescence parameters（CFP） are mainly epistatic effect.The additive effect and the epistatic effect are almost equal in the genetic effect of the QTL for the RWC HTI.