施氮处理下入侵植物黄顶菊表观遗传变异与表型可塑性响应特征

为明确不同氮素水平对黄顶菊入侵性的影响,本文模拟4种农田施氮梯度,采用甲基化敏感扩增多态性(MethylationSensitive Amplification Polymorphism,MSAP)技术研究不同处理下黄顶菊叶片DNA甲基化的变化特征,以及黄顶菊生物量、生长和光合生理指标的表型可塑性响应特征。结果表明:18对引物共扩增出690条MSAP条带,引物多态性百分比为86.38%,T2(275 kg·hm~(-2))和T3(375 kg·hm~(-2))施氮处理下半甲基化和总甲基化水平变化差异显著,各施氮处理的全甲基化水平与CK处理比较变化差异显著;施氮量的升高显著增加了黄顶菊的生物量和根生物量分配,而降低了支持结构生物量分配,同时促进了植物的营养和生殖生长及其光合作用;施氮处理下黄顶菊花蕾数、叶面积指数和根生物量的表型可塑性指数最高,分别为0.824 7、0.666 0和0.531 1,而生物量分配和光合生理指标的表型可塑性指数相对较低,表明黄顶菊主要通过调节自身的营养和生殖生长及根生物量等指标来适应环境氮素水平的变化;表型可塑性与表观遗传变异相关性分析的结果表明,黄顶菊半甲基化、全甲基化和总甲基化水平分别与花蕾数、根生物量、株高、叶面积指数、根生物量呈显著负相关,而与叶生物量比呈显著正相关。

Responsive characteristics of Flaveria bidentis epigenetic variation and phenotypic plasticity under different nitrogen treatments

To clarify the effects of different nitrogen levels on Flaveria bidentis invasion, we simulated four nitrogen gradients of farmlands. Using the MSAP method, the DNA methylation variations and phenotypic plasticity responsive characteristics of the biomass, growth, and photosynthetic physiological indices of Flaveria bidentis were studied. The results showed that 18 pairs of primers amplified 690 MSAP bands and the percentage of primer polymorphism was 86.38%. The differences in the semi-methylation and total methylation levels were significant between the T2 (275 kg·hm^-2) and T3 (375 kg·hm^-2) treatments. The difference in the full-methylation level was significant between the CK and other treatments. The increasing nitrogen application rate significantly increased the biomass and root biomass allocation of Flaveria bidentis and promoted vegetative and reproductive growth as well as plant photosynthesis, but decreased the biomass allocation of the support structure. Under nitrogen treatment, the phenotypic plasticity index of flower buds, leaf area index, and root biomass of Flaveria bidentis were the highest, i.e., 0.824 7, 0.666 0, and 0.531 1, respectively. Whereas the phenotypic plasticity index of biomass allocation and photosynthetic physiological index were much lower, which may indicate that Flaveria bidentis adapts to nitrogen changes mainly by regulating its own nutrition, reproductive growth, and root biomass. The results of correlation analysis between phenotypic plasticity and epigenetic variation showed that a significant negative correlation existed between the semi-methylated level and the number of buds as well as root biomass, between the full-methylated level and plant height as well as the leaf area index, and also between the total methylated level and root biomass, while a significant positive correlation existed only between the total methylated level and leaf biomass.