转录组分析拟南芥对锰胁迫及恢复过程中的分子响应

Transcriptional analysis of the molecular response of Arabidopsis to manganese stress and recovery

摘要:

锰是植物必需元素，参与多种代谢过程，然而，锰过量会对植物造成毒害。为探究植物在锰胁迫和恢复期的各种生理生化活动规律，本研究以拟南芥(Arabidopsis)为实验对象，将在MS培养基上生长5 d的幼苗，分别置于含1 mmol/L MnCl₂的MS培养基上1 d和3 d，随后将锰处理3 d的幼苗转移到MS培养基上恢复1 d进行各种生理指标检测及转录组分析。结果显示，拟南芥在恢复阶段叶片出现轻微变黄症状，叶绿素和类胡萝卜素浓度显著减少，而丙二醛(malondialdehyde, MDA)和可溶性糖含量在恢复阶段增加。转录组测序数据显示，差异基因的表达模式呈现三大类型：早期响应、晚期响应和恢复期响应。京都基因与基因组百科全书(Kyoto encylopaedia of genes and genomes, KEGG)通路富集分析发现，差异代谢通路包括植物激素信号传导(plant hormone signal transduction)、丝裂原活化蛋白激酶(mitosolysis activates protein kinase, MAPK)信号通路、苯丙烷合成代谢途径(phenylpropanoid biosynthesis)、ABC转运蛋白(ATP binding cassette transporters)和甘油磷脂代谢(glycosphingolipid biosynthesis)等。在锰胁迫及恢复阶段，筛选到了与苯丙烷合成代谢途径、ABC转运蛋白和甘油磷脂代谢相关的差异表达基因(differentially expressed genes, DEGs)，随机选取16个差异基因进行qRT-PCR验证，结果与RNA-seq数据表达趋势一致。结果表明，植物可能通过调节苯丙烷类合成代谢途径，促进多酚类物质的积累以清除在恢复阶段产生的过氧化物；激活ABC转运蛋白，提高锰离子在植物体内的运输，减轻锰离子对植物的毒害作用；通过启动甘油磷脂代谢，调整细胞膜脂组成和含量，以适应锰胁迫。本研究结果为拟南芥应对锰胁迫并恢复时作出反应的分子机理提供了新见解，也为植物耐锰新品种培育提供了参考。

Abstract:

Manganese (Mn) is an essential element for plants and plays a role in various metabolic processes. However, excess manganese can be toxic to plants. This study aimed to analyze the changes in various physiological activities and the transcriptome of Arabidopsis under different treatments: 1 mmol/L MnCl₂ treatment for 1 day or 3 days, and 1 day of recovery on MS medium after 3 days of MnCl₂ treatment. During the recovery phase, minor yellowing symptoms appeared on the leaves of Arabidopsis, and the content of chlorophyll and carotenoid decreased significantly, but the content of malondialdehyde and soluble sugar increased rapidly. Transcriptome sequencing data shows that the expression patterns of differentially expressed genes exhibit three major models: initial response model, later response model, recovery response model. Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis identified several affected metabolic pathways, including plant hormone signal transduction mitosolysis activates protein kinase (MAPK) phytohormone signaling, phenylpropanoid biosynthesis, ATP binding cassette transporters (ABC transporter), and glycosphingolipid biosynthesis. Differential expressed genes (DEGs) involved in phenylpropanoid biosynthesis, ABC transporter, and glycosphingolipid biosynthesis, were identified. Sixteen randomly selected DEGs were validated through qRT-PCR and showed consistent results with RNA-seq data. Our findings suggest that the phenylpropanoid metabolic pathway is activated to scavenge reactive oxygen species, the regulation of ABC transporter improves Mn transport, and the adjustment of cell membrane lipid composition occurs through glycerophospholipid metabolism to adapt to Mn stress in plants. This study provides new insights into the molecular response of plants to Mn stress and recovery, as well as theoretical cues for cultivating Mn-resistant plant varieties.