Comparative studies of thermotolerance: different modes of heat acclimation between tolerant and intolerant aquatic plants of the genus Potamogeton
Comparative studies of thermotolerance: different modes of heat acclimation between tolerant and intolerant aquatic plants of the genus Potamogeton
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DOI：
10.1093/aob/mcr300
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发表时间：
2012-02-01
期刊：
影响因子：
4.2
通讯作者：
Kosuge, Keiko
中科院分区：
文献类型：
--
作者：
Amano, Momoe;Iida, Satoko;Kosuge, Keiko
背景与目的基于分子的耐热性研究很少在野生植物上进行，尽管这一特性对夏季生存至关重要。在此，我们重点研究了在陆地上存活不同的两种近缘水生植物的耐热性和热休克转录因子A2(HSFA2)及其可能的靶基因(叶绿体定位的小热休克蛋白，CP-SHSP)的表达。方法采用叶绿素生物测定法测定植物在非驯化和高温驯化条件下的耐热性。结果热胁迫对叶绿素积累的抑制结果表明，海棠具有较高的基础耐热性，并形成了获得性耐热性，而贯叶海棠是热敏性的，不能获得耐热性。我们在每个物种中发现了两个重复的HSFA2和CP-SHSP基因。这些基因在热休克条件下均能在松材线虫中诱导表达，而在串叶松材线虫中未诱导出1个HSFA2a基因。在未经热驯化的植物中，HSFA2和CP-SHSP的转录水平在热激后瞬时升高。在受热驯化的植物中，在亚致死热休克过程中，马来毛白杨的转录本持续被诱导，而在全叶毛白杨中则没有。相反，CP-SHSP基因的最低热诱导阈值温度提高。结论我们的耐热性比较研究表明，热驯化导致了物种特有的热响应变化。获得性耐热性的形成有利于在极端温度下生存。然而，在热反应的最低阈值温度下丧失获得性耐热性和可塑性，可能有利于生长在日和季节温度波动有限的适度生境中的植物。
Background and Aims Molecular-based studies of thermotolerance have rarely been performed on wild plants, although this trait is critical for summer survival. Here, we focused on thermotolerance and expression of heat shock transcription factor A2 (HSFA2) and its putative target gene (chloroplast-localized small heat shock protein, CP-sHSP) in two allied aquatic species of the genus Potamogeton (pondweeds) that differ in survival on land.Methods The degree of thermotolerance was examined using a chlorophyll bioassay to assess heat injury in plants cultivated under non-and heat-acclimation conditions. Potamogeton HSFA2 and CP-sHSP genes were identified and their heat-induction was quantified by real-time PCR.Key Results The inhibition of chlorophyll accumulation after heat stress showed that Potamogeton malaianus had a higher basal thermotolerance and developed acquired thermotolerance, whereas Potamogeton perfoliatus was heat sensitive and unable to acquire thermotolerance. We found two duplicated HSFA2 and CP-sHSP genes in each species. These genes were induced by heat shock in P. malaianus, while one HSFA2a gene was not induced in P. perfoliatus. In non-heat-acclimated plants, transcript levels of HSFA2 and CP-sHSP were transiently elevated after heat shock. In heat-acclimated plants, transcripts were continuously induced during sublethal heat shock in P. malaianus, but not in P. perfoliatus. Instead, the minimum threshold temperature for heat induction of the CP-sHSP genes was elevated in P. perfoliatus.Conclusions Our comparative study of thermotolerance showed that heat acclimation leads to species-specific changes in heat response. The development of acquired thermotolerance is beneficial for survival at extreme temperatures. However, the loss of acquired thermotolerance and plasticity in the minimum threshold temperature of heat response may be favourable for plants growing in moderate habitats with limited daily and seasonal temperature fluctuations.