cDNA Cloning and characterization of jasmonic acid-responsive genes in suspension-cultured rice cells

植物对真菌、细菌和病毒等病原体的防御反应涉及诱导合成称为植物保卫素的低分子化合物。来自病原微生物和寄主植物细胞表面的生物激发子触发防御反应。据认为，激发子分子与植物膜受体结合，并激活一系列特定基因，导致植物保卫素的合成。在悬浮培养的水稻细胞中，茉莉酸在激发子N-乙酰基壳七糖诱导植物抗菌素-双内酯A的生物合成中起着信号转导的作用。为了研究茉莉酸在水稻细胞中的作用方式，我们尝试了茉莉酸应答基因的克隆。通过对悬浮培养水稻细胞…文库的差异筛选，获得了3个cDNA克隆(cRRJ1、cEEJ2和cRRJ4)和1个cDNA克隆(cRERJ1用10-4M的外消旋茉莉酸分别处理2小时和30分钟。RRJ1编码一种与催化含硫氨基酸合成或代谢的酶同源的多肽。RRJ2编码的多肽与水稻和玉米中的丙酮酸脱羧酶高度同源，可能与水稻细胞在缺氧条件下的能量需求有关。RRJ4推测的多肽与古老的黄酶超家族成员同源，其生物学功能尚待阐明。RERJ1编码一个可能的多肽，在羧基末端附近含有一个碱性区域/螺旋-环-螺旋(BHLH)结构域。由于bHLH蛋白是一种普遍存在的转录因子，到目前为止几乎所有的真核细胞中都发现了这种转录因子，RERJ1可能在茉莉酸在悬浮培养细胞中的信号转导途径中发挥重要作用。这是关于茉莉酸反应的转录因子基因存在的第一个信息。较少

Plant defense reactions against pathogens such as fungi, bacteria, and viruses involve induced synthesis of low molecular weight compounds called phytoalexins. Biotic elicitors which are derived from the cell surface of pathogenic microbes as well as host plants tRIgger the defense response. It is considered that an elicitor molecule is combined with a plant membrane receptor, and that the complex activates a series of specific genes, resulting in the synthesis of phytoalexins. We have suggested that jasmonic acid functions as a signal transducer in the induction of biosynthesis of the phytoalexin momilactone A by the elicitor N-acetylchitoheptaose in suspension-cultured rice cells. To investigate mode of action of jasmonic acid in the rice cells, we attempted cDNA cloning of jasmonic acidresponsive genes. Three cDNA clones ( cRRJ1, cEEJ2, and cRRJ4 ) and one cDNA clone ( cRERJ1 ) were isolated by differential screening of cDNA libraries prepared from suspensioned-cultured rice cells t … More reated with 10-4 M of racemic jasmonic acid for 2 hours and 30 minutes, respectively. RRJ1 encodes a putative polypeptide that is homologous to enzymes catalyzing synthesis or metabolism of sulful-containing amino acids. RRJ2 encodes a putative polypeptide that is highly homologous to pyrvate decarboxylases from rice and maize, and probably contributes to aquirement of energy in rice cells under the anairoic condition. The putative polypeptide by RRJ4 is homelogous to members of old yellow enzyme superfamily biological functions of which remains to be clarified. RERJ1 encodes a putative polypeptide that contains a basic region/helix-loop-helix ( bHLH ) domain near the carboxyl terminus. Since bHLH proteins are ubiquitous transcription factors that have been found virtually all eukaryotes examined to date, RERJ1 might play one of important roles in the signal transduction pathway of jasmonic acid in he suspension-cultured cells. This is the first information on the presence of a transcription factor gene that is responsive to jasmonic acid. Less