Kim Y S, Choi D, Lee M M, Lee S H, Kim W T
Department of Biology, College of Science, Yonsei University, Seoul, Korea.
Plant Cell Physiol. 1998 Jun;39(6):565-73. doi: 10.1093/oxfordjournals.pcp.a029406.
Three full length 1-aminocyclopropane-1-carboxylate (ACC) oxidase cDNA clones (pNG-ACO1, 1,254 bp; pNG-ACO2, 1,198 bp; and pNG-ACO3, 1,053 bp) were isolated from the TMV-treated leaf cDNA library of Nicotiana glutinosa plant. They share a high degree of sequence identity (78-81%) throughout the coding regions but are divergent within the 3'-untranslated regions. The gene-specific probes were prepared using these regions to investigate the differential expression of the ACC oxidase gene family in various organs and in response to a multitude of biotic and abiotic stresses in N. glutinosa plants. All three genes were transcriptionally active displaying unique patterns of expression. Both the pNG-ACO1 and pNG-ACO3 transcripts highly accumulated during the senescence of leaves, while the pNG-ACO2 mRNA was constitutively present. In addition, the NG-ACO1 and NG-ACO3 transcripts were predominantly found in roots whereas the NG-ACO2 mRNA was mainly in stems. Upon TMV infection, both NG-ACO1 and NG-ACO3 were markedly induced, but in mock treatment which has an effect of mild wounding, only the NG-ACO3 gene was induced. Furthermore, salicylic acid and CuSO4 treatments of leaves increased the level of NG-ACO1 and NG-ACO3 transcripts, while they did not affect the NG-ACO2 gene expression. Results showed that both the NG-ACO1 and NG-ACO3 genes were highly inducible by ethylene and methyl jasmonate treatments, with NG-ACO3 being more responsive. By contrast, NG-ACO2 did not respond to these growth regulators. Thus, it appears that there are two groups of ACC oxidase transcripts expressed in leaf tissue of N. glutinosa, either stress-induced or constitutive. The possible molecular mechanism of differential regulation of ACC oxidase gene expression and its physiological significance are discussed.
从烟草叶烟草花叶病毒（TMV）处理的叶片cDNA文库中分离出三个全长1-氨基环丙烷-1-羧酸（ACC）氧化酶cDNA克隆（pNG-ACO1，1254 bp；pNG-ACO2，1198 bp；pNG-ACO3，1053 bp）。它们在整个编码区具有高度的序列同一性（78 - 81%），但在3'-非翻译区存在差异。利用这些区域制备基因特异性探针，以研究ACC氧化酶基因家族在烟草不同器官中的差异表达以及对多种生物和非生物胁迫的响应。所有三个基因都具有转录活性，呈现出独特的表达模式。pNG-ACO1和pNG-ACO3转录本在叶片衰老过程中高度积累，而pNG-ACO2 mRNA则组成性存在。此外，NG-ACO1和NG-ACO3转录本主要在根中发现，而NG-ACO2 mRNA主要在茎中。在TMV感染后，NG-ACO1和NG-ACO3均被显著诱导，但在具有轻度创伤效应的模拟处理中，只有NG-ACO3基因被诱导。此外，叶片用水杨酸和硫酸铜处理增加了NG-ACO1和NG-ACO3转录本的水平，但不影响NG-ACO2基因的表达。结果表明，NG-ACO1和NG-ACO3基因均对乙烯和茉莉酸甲酯处理高度诱导，其中NG-ACO3反应更敏感。相比之下，NG-ACO2对这些生长调节剂无反应。因此，似乎在烟草叶组织中有两组ACC氧化酶转录本表达，一组是胁迫诱导型，另一组是组成型。本文还讨论了ACC氧化酶基因表达差异调控的可能分子机制及其生理意义。
