Differential gene expression in shoots and roots under heat stress for a geothermal and non-thermal Agrostis grass species contrasting in heat tolerance
Differential gene expression in shoots and roots under heat stress for a geothermal and non-thermal Agrostis grass species contrasting in heat tolerance
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DOI：
10.1016/j.envexpbot.2007.11.011
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发表时间：
2008-05
影响因子：
5.7
通讯作者：
Jichen Xu;F. Belanger;Bingru Huang
中科院分区：
文献类型：
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作者：
Jichen Xu;F. Belanger;Bingru Huang
鉴定与耐热性相关的基因对于开发耐热植物非常重要。本研究的目的是比较两种剪股草属草种在芽和根中差异表达的基因，对比不同温度条件下的耐热性，并鉴定与剪股草属草种热应激适应相关的上调基因。耐热、耐热的 A. scabra 适合黄石国家公园地热地区，而热敏感的 A. stolonifera 则在凉爽气候地区用作草坪和饲料草，在生长室中暴露于 20 或 40°C 的温度下。在处理第 7 天对叶和根进行取样，以评估对热应激的生理反应并进行差异显示分析。与匍匐黄芪相比，热胁迫后 7 天的热胁迫后，热黄芪仍保持显着更高的叶片叶绿素含量和根系活力，并且电解质渗漏 (EL) 更低。叶片样品的差异显示分析显示，在热胁迫的匍匐花中，21 个基因片段下调，而 18 个基因片段上调。对于热A.scabra，在热胁迫下有38个基因片段下调，22个基因片段上调。发现根中的四个基因片段在热应激下上调。 RT-PCR 分析证实，叶中的一个基因片段 (AsL9) 和根中的两个基因片段 (AsR1 和 AsR2) 仅在暴露于热胁迫的热 A.scabra 中表达。热 A. scabra 中的这些热诱导基因可能有助于其在地热地区长期高温土壤中生存的卓越能力。 BLASTX 的推定功能分析发现，两个物种中大多数上调的基因都涉及应激防御途径或耐受机制，例如细胞壁弹性、次级代谢、调节功能和蛋白质合成。
Identification of genes associated with heat tolerance is important for developing heat-tolerant plants. The objectives of this study were to compare genes differentially expressed in shoots and roots in two Agrostis grass species contrasting in heat tolerance under different temperature regimes and to identify up-regulated genes associated with heat-stress adaptation in Agrostis grass species. Heat-tolerant, thermal A. scabra, adapted to geothermal areas in Yellowstone National Park, and heat-sensitive A. stolonifera, used as a turf and forage grass in cool climatic regions, were exposed to 20 or 40°C in growth chambers. Leaves and roots were sampled at 7 day of treatment to evaluate physiological responses to heat stress and to perform differential display analysis. Thermal A. scabara maintained significantly higher leaf chlorophyll content and root viability and lower electrolyte leakage (EL) following 7 day of heat stress, compared to A. stolonifera. Differential display analysis of leaf samples revealed that 21 gene fragments were down-regulated while 18 fragments were up-regulated in heat-stressed A. stolonifera. For thermal A. scabra, 38 gene fragments were down-regulated and 22 fragments were up-regulated under heat stress. Four gene fragments in roots were found to be up-regulated under heat stress. RT-PCR analysis confirmed that one gene fragment in leaves (AsL9) and two gene fragments in roots (AsR1 and AsR2) were expressed only in thermal A. scabra exposed to heat stress. These heat-inducible genes in thermal A. scabra may contribute to its superior ability to survive in chronically high-temperature soils in geothermal areas. Putative functional analysis with BLASTX found that most of the up-regulated genes in both species were involved in stress defense pathways or tolerance mechanisms, such as cell wall elasticity, secondary metabolism, regulatory functions, and protein synthesis.