苦瓜叶片叶绿素响应白粉病菌侵染的遗传分析

为了探索苦瓜苗期叶片叶绿素a、叶绿素b以及总叶绿素响应白粉病菌侵染的遗传规律,以苦瓜高代自交系09-a与09-b为亲本构建的170个F₂个单株和140个F_2:3家系作为材料,利用植物数量遗传的主基因+多基因混合遗传模型分别对2个地点的2个群体进行基于单个分离世代群体的遗传分析。结果表明,白粉病菌胁迫下叶绿素a、叶绿素b以及总叶绿素含量均会降低,感病品系降低幅度显著大于抗病品系,降解量与病情指数呈正相关,且降解量在2个群体中均呈正态分布。F₂和F_2:3群体中叶绿素a和叶绿素b的降解量均由一对加性主基因决定,2个群体控制叶绿素a降解量的1对主基因加性效应分别为0.3151、0.1670,控制叶绿素b降解量的1对主基因加性效应分别为0.1333、0.1670。总叶绿素降解量受2对加性–显性主基因控制,2对主基因在F₂群体中加性效应分别为0.2601、0.3184,显性效应为?0.3452、?0.2221,在F_2:3群体加性效应分别为0.1892、0.1624,显性效应分别为?0.0465、?0.0897,2对主基因的加性和显性效应共同发挥着重要作用。3个性状的加性效应均为正值,且控制总叶绿素降解量的2对主基因均以加性效应为主。F₂和F_2:3群体中叶绿素a降解量主基因遗传率为76.40%、62.68%。叶绿素b降解量主基因遗传率分别为72.99%、62.86%,控制叶绿素降解量的2对主基因遗传率为65.25%、95.36%,遗传率均大于60%,表明白粉菌胁迫下叶绿素a、叶绿素b及总叶绿素的降解主要受主基因的控制,但也受部分环境的影响。在苦瓜白粉病抗性育种实践中,可将叶绿素相关性状的降低量结合病情指数在早期世代进行选择。本研究为探索苦瓜白粉病抗病机理和抗病育种提供了理论依据。

Genetic Law of Chlorophyll Response to Powdery Mildew Infection in Bitter Melon Leaves

In order to explore the genetic law of chlorophyll a, chlorophyll b and chlorophyll in response to powdery mildew infection in bitter melon seedlings, 170 individual plants of F₂ and 140 families of F_2:3 were constructed with bitter melon high-generation inbred lines 09-a and 09-b, The genetic analysis of two populations in two environments based on a single separated generation population was carried out using the major gene + polygene mixed genetic model of plant quantitative inheritance. The results showed that the contents of chlorophyll a, chlorophyll b and chlorophyll decreased under the stress of powdery mildew. The reduction range of susceptible strains was significantly greater than that of resistant strains. The degradation amount was positively correlated with the disease index, and the degradation amount was normally distributed in the two populations. The degradation amounts of chlorophyll a and chlorophyll b in F₂ and F_2:3 populations were determined by a pair of additive major genes. The additive effect of a pair of major genes controlling the degradation amount of chlorophyll a in the two populations was 0.3151 and 0.1670 respectively, and the additive effects of a pair of major genes controlling the degradation amount of chlorophyll b was 0.1333 and 0.1670 respectively. The chlorophyll degradation was controlled by two pairs of additive dominant major genes. The additive effect of the two pairs of major genes in F₂ population was 0.2601 and 0.3184, the dominant effect was ?0.3452 and -0.2221, and the additive effect in F_2:3 population was 0.1892 and 0.1624, the dominant effect was -0.0465 and ?0.0897, respectively. The additive and dominant effects of the two pairs of major genes played an important role together. The additive effects of the three traits were positive, and the two pairs of major genes controlling the chlorophyll degradation were dominated by additive effects. The major gene heritability of chlorophyll a degradation in F₂ and F_2:3 populations was 76.40% and 62.68%. The heritabilities of major genes controlling chlorophyll b degradation was 72.99% and 62.86%, respectively. And the heritability of two pairs of major genes controlling chlorophyll b degradation was 65.25% and 95.36%, both were greater than 60%, indicating that chlorophyll a, chlorophyll b and chlorophyll degradation were mainly controlled by main genes under powdery mildew stress, but it was also affected by some environment. In the breeding practice of bitter melon powdery mildew resistance, the reduction of chlorophyll related traits could be selected in the early generation combined with the disease index. This study would provide a theoretical basis for exploring the disease resistance mechanism and disease resistance breeding of bitter melon powdery mildew.