【摘要】 皇竹草是一种高产、优质牧草,但因耐寒性较差而极大限制了其在我国大面积种植和推广.选择在冬季平均温度接近皇竹草耐寒极限温度的四川地区进行了5年自然驯化,筛选在最低温度-5℃下能够自然过冬的样本,并在冬季最低温度下和夏季最高温度下分别取样进行转录组测序,挖掘皇竹草本身具有的耐寒、抗冻基因.结果显示:皇竹草转录组共有转录本125 467条,注释转录本65 633条,注释信息及邻近分析显示皇竹草与小米、玉米高度同源.冬夏两季皇竹草比较转录组分析共计筛选差异表达基因11 443个,其中冬季相对于夏季表达量上调基因6 943个,下调基因4 500个,差异显著.在以上差异表达基因中,共计挖掘在冬季低温条件下高度表达的抗冻基因112个,且有17个抗冻基因在冬季样品中特异表达.随机选取6个差异表达的抗冻基因进行荧光定量PCR实验验证,结果显示与预测转录本表达量一致.本研究对皇竹草进行了转录组测序并通过比较转录组的方法挖掘其在自然驯化条件下成功越冬样本中的抗冻基因,有利于揭示皇竹草冷适应下的抗性机制,同时也有助于热带引种植物分子育种的开展.更多还原

【Abstract】 Pennisetum sinese Roxb is a high-quality and high-yield grass from South America.Because of its high propagation efficiency,forage palatability,and nutritional value,P.sinese could be widely used as livestock feed.However,it does not naturally hibernate in northern regions because of it low cold resistance,which restricts its growth and spread across China.In this study,the natural domestication of P.sinese for 5 years in Sichuan province,where the mean winter temperature is close to the sample cold-resistance limit,was analyzed,samples of plants that survived at-5 ℃ in the winter were identified,and whole transcriptomes of plants collected at the lowest temperature in winter and highest temperature in summer were sequenced.The transcriptome of P.sinese comprised 125 467 transcripts,of which 65 633 had been annotated.Annotation and proximity analyses showed that the transcriptome of P.sinese is highly similar to those of millet(Setaria italica) and maize(Zea mays).There were 11 443 differentially expressed genes(DEGs) identified through comparative transcriptome analysis,with 6 943 genes significantly upregulated in the winter relative to those upregulated in the summer,and 4 500 genes significantly downregulated.Of all of the DEGs,there were 112 cold-tolerance genes that were highly expressed in winter,17 of which were specifically expressed in these conditions.Quantitative PCR was used to verify the expression levels of six randomly selected differentially expressed cold-tolerance genes,and the results showed that their expression levels were consistent with those predicted.In this study,the transcriptomes of natural domesticated P.sinese were sequenced,and cold-tolerance genes were identified in plants that had successfully overwintered.These results contribute to an understanding of the cold adaptation mechanisms of P.sinese and inform the breeding of introduced tropical plants.更多还原