Kishimoto Kyutaro, Matsui Kenji, Ozawa Rika, Takabayashi Junji
Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Kawaguchi, Saitama, 332-0012 Japan.
Plant Cell Physiol. 2005 Jul;46(7):1093-102. doi: 10.1093/pcp/pci122. Epub 2005 May 6.
Green leafy volatiles or isoprenoids are produced after mechanical wounding or pathogen/herbivore attacks in higher plants. We monitored expression profiles of the genes involved in defense responses upon exposing Arabidopsis thaliana to the volatiles. Among the genes investigated, those known to be induced by mechanical wounding and/or jasmonate application, such as chalcone synthase (CHS), caffeic acid-O-methyltransferase (COMT), diacylglycerol kinase1 (DGK1), glutathione-S-transferase1 (GST1) and lipoxygenase2 (LOX2), were shown to be induced with (E)-2-hexenal, (Z)-3-hexenal, (Z)-3-hexenol or allo-ocimene (2,6-dimethyl-2,4,6-octatriene). A salicylic acid-responsive gene, pathogenesis-related protein2 (PR2), was not induced by the volatiles. Detailed analyses of the expression profiles showed that the manner of induction varied depending on either the gene monitored or the volatile used. A chemically inert compound, (Z)-3-hexenol, was also potent, which suggested that chemical reactivity was not the sole requisite for the inducing activity. With a jasmonate-insensitive mutant (jar1), the induction by the volatiles was mostly suppressed, however, that of LOX2 was unaltered. An ethylene-insensitive mutant (etr1) showed responses almost identical to the wild type, with minor exceptions. From these observations, it was suggested that both the jasmonate-dependent and -independent pathways were operative upon perception of the volatiles, while the ETR1-dependent pathway was not directly involved. When Botrytis cinerea was inoculated after the volatile treatment, retardation of disease development could be seen. It appears that volatile treatment could make the plants more resistant against the fungal disease.
绿叶挥发物或类异戊二烯是高等植物在受到机械损伤或病原体/食草动物攻击后产生的。我们监测了拟南芥暴露于这些挥发物后参与防御反应的基因的表达谱。在所研究的基因中，那些已知受机械损伤和/或茉莉酸诱导的基因，如查尔酮合酶（CHS）、咖啡酸-O-甲基转移酶（COMT）、二酰基甘油激酶1（DGK1）、谷胱甘肽-S-转移酶1（GST1）和脂氧合酶2（LOX2），被证明会被（E）-2-己烯醛、（Z）-3-己烯醛、（Z）-3-己烯醇或罗勒烯（2,6-二甲基-2,4,6-辛三烯）诱导。水杨酸响应基因病程相关蛋白2（PR2）未被这些挥发物诱导。对表达谱的详细分析表明，诱导方式因所监测的基因或所使用的挥发物而异。化学惰性化合物（Z）-3-己烯醇也具有诱导活性，这表明化学反应性不是诱导活性的唯一必要条件。对于茉莉酸不敏感突变体（jar1），挥发物的诱导作用大多受到抑制，然而，LOX2的诱导作用未改变。乙烯不敏感突变体（etr1）表现出与野生型几乎相同的反应，只有少数例外。从这些观察结果可以看出，在感知挥发物时，茉莉酸依赖和非依赖途径均起作用，而ETR1依赖途径不直接参与。在挥发物处理后接种灰葡萄孢菌时，可以看到疾病发展受到抑制。似乎挥发物处理可以使植物对真菌病害更具抗性。
