Rizhsky Ludmila, Liang Hongjian, Mittler Ron
Department of Biology, Technion-Israel Institute of Technology, Technion City, Haifa 32000, Israel.
Plant Physiol. 2002 Nov;130(3):1143-51. doi: 10.1104/pp.006858.
In nature, plants encounter a combination of environmental conditions that may include stresses such as drought or heat shock. Although drought and heat shock have been extensively studied, little is known about how their combination affect plants. We used cDNA arrays, coupled with physiological measurements, to study the effect of drought and heat shock on tobacco (Nicotiana tabacum) plants. A combination of drought and heat shock resulted in the closure of stomata, suppression of photosynthesis, enhancement of respiration, and increased leaf temperature. Some transcripts induced during drought, e.g. those encoding dehydrin, catalase, and glycolate oxidase, and some transcripts induced during heat shock, e.g. thioredoxin peroxidase, and ascorbate peroxidase, were suppressed during a combination of drought and heat shock. In contrast, the expression of other transcripts, including alternative oxidase, glutathione peroxidase, phenylalanine ammonia lyase, pathogenesis-related proteins, a WRKY transcription factor, and an ethylene response transcriptional co-activator, was specifically induced during a combination of drought and heat shock. Photosynthetic genes were suppressed, whereas transcripts encoding some glycolysis and pentose phosphate pathway enzymes were induced, suggesting the utilization of sugars through these pathways during stress. Our results demonstrate that the response of plants to a combination of drought and heat shock, similar to the conditions in many natural environments, is different from the response of plants to each of these stresses applied individually, as typically tested in the laboratory. This response was also different from the response of plants to other stresses such as cold, salt, or pathogen attack. Therefore, improving stress tolerance of plants and crops may require a reevaluation, taking into account the effect of multiple stresses on plant metabolism and defense.
在自然界中，植物会遭遇多种环境条件的组合，其中可能包括干旱或热激等胁迫。尽管干旱和热激已得到广泛研究，但对于它们的组合如何影响植物却知之甚少。我们使用cDNA阵列，并结合生理测量，来研究干旱和热激对烟草（Nicotiana tabacum）植株的影响。干旱和热激的组合导致气孔关闭、光合作用受抑制、呼吸作用增强以及叶片温度升高。一些在干旱期间诱导产生的转录本，例如那些编码脱水素、过氧化氢酶和乙醇酸氧化酶的转录本，以及一些在热激期间诱导产生的转录本，例如硫氧还蛋白过氧化物酶和抗坏血酸过氧化物酶，在干旱和热激组合期间受到抑制。相反，其他转录本的表达，包括交替氧化酶、谷胱甘肽过氧化物酶、苯丙氨酸解氨酶、病程相关蛋白、一个WRKY转录因子和一个乙烯反应转录共激活因子，在干旱和热激组合期间被特异性诱导。光合基因受到抑制，而编码一些糖酵解和磷酸戊糖途径酶的转录本被诱导，这表明在胁迫期间通过这些途径利用糖类。我们的结果表明，植物对干旱和热激组合的反应，类似于许多自然环境中的条件，不同于植物对单独施加的每种胁迫的反应，如通常在实验室中测试的那样。这种反应也不同于植物对其他胁迫如寒冷、盐分或病原体攻击的反应。因此，提高植物和作物的胁迫耐受性可能需要重新评估，要考虑到多种胁迫对植物代谢和防御的影响。
