Larkindale Jane, Hall Jennifer D, Knight Marc R, Vierling Elizabeth
Department of Biochemistry and Molecular Biophysics , University of Arizona, Tucson, Arizona 85721, USA.
Plant Physiol. 2005 Jun;138(2):882-97. doi: 10.1104/pp.105.062257. Epub 2005 May 27.
To investigate the importance of different processes to heat stress tolerance, 45 Arabidopsis (Arabidopsis thaliana) mutants and one transgenic line were tested for basal and acquired thermotolerance at different stages of growth. Plants tested were defective in signaling pathways (abscisic acid, salicylic acid, ethylene, and oxidative burst signaling) and in reactive oxygen metabolism (ascorbic acid or glutathione production, catalase) or had previously been found to have temperature-related phenotypes (e.g. fatty acid desaturase mutants, uvh6). Mutants were assessed for thermotolerance defects in seed germination, hypocotyl elongation, root growth, and seedling survival. To assess oxidative damage and alterations in the heat shock response, thiobarbituric acid reactive substances, heat shock protein 101, and small heat shock protein levels were determined. Fifteen mutants showed significant phenotypes. Abscisic acid (ABA) signaling mutants (abi1 and abi2) and the UV-sensitive mutant, uvh6, showed the strongest defects in acquired thermotolerance of root growth and seedling survival. Mutations in nicotinamide adenine dinucleotide phosphate oxidase homolog genes (atrbohB and D), ABA biosynthesis mutants (aba1, aba2, and aba3), and NahG transgenic lines (salicylic acid deficient) showed weaker defects. Ethylene signaling mutants (ein2 and etr1) and reactive oxygen metabolism mutants (vtc1, vtc2, npq1, and cad2) were more defective in basal than acquired thermotolerance, especially under high light. All mutants accumulated wild-type levels of heat shock protein 101 and small heat shock proteins. These data indicate that, separate from heat shock protein induction, ABA, active oxygen species, and salicylic acid pathways are involved in acquired thermotolerance and that UVH6 plays a significant role in temperature responses in addition to its role in UV stress.
为了研究不同过程对热胁迫耐受性的重要性，我们对45个拟南芥（Arabidopsis thaliana）突变体和1个转基因系在生长的不同阶段进行了基础耐热性和获得性耐热性测试。所测试的植株在信号通路（脱落酸、水杨酸、乙烯和氧化爆发信号通路）以及活性氧代谢（抗坏血酸或谷胱甘肽生成、过氧化氢酶）方面存在缺陷，或者之前已被发现具有与温度相关的表型（如脂肪酸去饱和酶突变体、uvh6）。对突变体在种子萌发、下胚轴伸长、根生长和幼苗存活方面的耐热性缺陷进行了评估。为了评估氧化损伤和热休克反应的变化，测定了硫代巴比妥酸反应性物质、热休克蛋白101和小热休克蛋白的水平。15个突变体表现出显著的表型。脱落酸（ABA）信号突变体（abi1和abi2）以及紫外线敏感突变体uvh6在根生长和幼苗存活的获得性耐热性方面表现出最强的缺陷。烟酰胺腺嘌呤二核苷酸磷酸氧化酶同源基因（atrbohB和D）的突变、ABA生物合成突变体（aba1、aba2和aba3）以及NahG转基因系（水杨酸缺陷型）表现出较弱的缺陷。乙烯信号突变体（ein2和etr1）和活性氧代谢突变体（vtc1、vtc2、npq1和cad2）在基础耐热性方面比获得性耐热性更有缺陷，尤其是在高光条件下。所有突变体积累的热休克蛋白101和小热休克蛋白水平均与野生型相当。这些数据表明，除了热休克蛋白的诱导外，ABA、活性氧和水杨酸途径参与了获得性耐热性，并且UVH6除了在紫外线胁迫中发挥作用外，在温度反应中也起着重要作用。
