基于杂交种光合特性解析烟叶生物量杂种优势的形成机制

Analysis of Photosynthetic Characteristics of Hybrid Species and the Formation Mechanism of Biomass Heterosis in Tobacco Leaves

为从光合生理角度解析烟叶生物量杂种优势的形成机制,本研究以生物量差异较大的6个亲本及其杂交组合为材料,测定其烟叶生物量、光合特性、叶绿素含量及光合相关基因的表达量,分析了烟叶生物量杂种优势与光合特性间的关系,并基于杂交种的光合特性解析烟叶生物量杂种优势形成的基础。结果表明,烟草杂交种的生物量具有普遍的杂种优势,超亲优势、中亲优势组合率分别达到55.56%、77.78%;杂交种净光合速率、胞间CO_(2)浓度、叶绿素a含量等光合相关指标也表现出普遍的杂种优势,超亲优势组合率分别为55.56%、100%、66.67%,中亲优势组合率分别为88.89%、100%、77.78%;生物量杂种优势与净光合速率达到显著相关关系,相关系数为0.73(p<0.05);NtLhcb1、NtLhcb2、NtPsbA、NtatpF、Ntrbcl基因相对表达量在强、弱优势杂交种间达到显著差异,与烟叶生物量杂种优势呈显著或极显著正相关。烟草杂交种中NtLhcb1、NtLhcb2、NtPsbA、NtatpF、Ntrbcl基因上调表达,可能促进了烟草杂交种光合能力增强。

To analyze the formation mechanism of biomass heterosis in tobacco leaves from the perspective of photosynthetic physiology,this study used six parents and their hybrid combinations with significant biomass differences to measure biomass,photosynthetic characteristics,chlorophyll contents,and expression levels of photosynthetic-related genes in the tested materials.The relationship between biomass heterosis in tobacco leaves and photosynthetic characteristics of hybrids as well as heterosis formation mechanism were analyzed based on the photosynthetic characteristics of these hybrid species.Results showed that the biomass of tobacco hybrids had heterosis,with high-parent heterosis and mid-parent heterosis rate of 55.56%and 77.78%.In addition,Photosynthetic related indicators such as net photosynthetic rate,intercellular CO_(2)concentration,and chlorophyll a content of the hybrid showed heterosis,with the combination rates of high-parent heterosis and mid-parent heterosis being 55.56%,100%,66.67%and 88.89%,100%,77.78%,respectively.There is a significant correlation between biomass heterosis and net photosynthetic rate,with correlation coefficients of 0.73(p<0.05).The relative expression levels of NtLhcb1,NtLhcb2,NtPsbA,NtatpF,and Ntrbcl genes related to photosynthesis showed significant differences between strong and weak heterosis hybrids,and their expression levels were significantly positively correlated with the heterosis of biomass.The results indicate that the up-regulation of NtLhcb1,NtLhcb2,NtPsbA,NtatpF,and Ntrbcl genes in the hybrids enhances the photosynthetic capacity of the hybrid.