施氮和黄顶菊混植对大喇叭口期玉米DNA甲基化变异的影响

试验设置4种玉米/黄顶菊混植比例,玉米单种(A1)、玉米/黄顶菊2∶1混种(A2)、玉米/黄顶菊4∶3混种(A3)、玉米/黄顶菊1∶1混种(A4),4种施氮梯度0(CK)、175(T1)、275(T2)、375 kg/hm^2(T3),采用甲基化敏感扩增多态性(Methylation Sensitive Amplification Polymorphism,MSAP)技术,研究不同处理下玉米叶片基因组DNA甲基化的变异特征。结果表明,筛选18对引物组合对各处理玉米叶片进行扩增,不同混植比例下各获得754条MSAP条带,在A1、A2、A3和A4混植比例下,对玉米表观遗传多样性贡献率最大的引物组合分别为EmHM21、EkHM17、EdHM21和EhHM17。A1混植比例下的未甲基化条带数、超甲基化条带数和总甲基化带数与其他3种混植比例条带数相比差异显著,4种混植比例下玉米叶片基因组DNA半甲基化和全甲基化条带数差异不显著,总甲基化条带数为79~93条,占比为10.84%~12.33%。与A1混植比例下相应施氮梯度相比,混植比例达到2∶1(A2)且施氮梯度达到175 kg/hm^2时,玉米叶片的半甲基化水平、全甲基化水平和总甲基化水平产生显著性差异。

Effects of Nitrogen Application and Different Mixed Planting Proportion of Flaveria bidentis on DNA Methylation Variation of Maize at Large Bell Stage

By MSAP technique, four maize/Flaveria bidentis mixed planting ratios and four nitrogen application gradients were set up to study the variability characteristics of genome DNA methylation of maize leaves under different treatments. The results showed that 18 pairs of primers were screened to amplify the genome DNA, and 754 MSAP bands were obtained from the maize leaves treated with different mixing ratios. Among four mixed ratios of A1, A2, A3 and A4, the primer combinations with the highest contribution rate to the epigenetic diversity of maize were EmHM21, EkHM17, EdHM21 and EhHM17, respectively. The number of unmethylated bands, hypermethylated bands and the total methylated bands in the A1 mixed ratio were significantly different from those in the other three mixed ratios, and there were no significant differences in the number of DNA hemimethylation and DNA permethylation bands in the four mixed ratios, while the number of total methylated bands was 79-93, accounting for 10.84%-12.33%. Comparing with the corresponding nitrogen application gradient under A1 mixed ratio, significant differences in levels of hemimethylation, permethylation, and total methylation of maize leaves can be found when the ratio of mixed planting was 2:1(A2) and the nitrogen application gradient reaches 175 kg/ha(T1).