León J, Rojo E, Titarenko E, Sánchez-Serrano J J
Centro Nacional de Biotecnologìa CSIC, Campus de Cantoblanco-UAM, Madrid, Spain.
Mol Gen Genet. 1998 May;258(4):412-9. doi: 10.1007/s004380050749.
We have used wound- and jasmonic acid (JA)-responsive genes as molecular markers to elucidate the pathway(s) of wound signal transduction in Arabidopsis thaliana. The JA-responsive (JR) genes JR1, JR2, and JR3 are strongly induced by wounding and by JA, while the wound-responsive (WR) genes WR3 and acyl CoA oxidase (ACO) are induced by wounding only. Accumulation of JR transcripts upon wounding was blocked by indomethacin. However, indomethacin did not affect either induction of these genes by JA or wound-induced expression of WR genes, suggesting that JA synthesis is only needed for wound-dependent induction of JR genes, and also that separate JA-dependent and -independent wound signal transduction pathways exist in Arabidopsis. The two pathways are differentially regulated by Ca2+ and calmodulin. Mobilization of intracellular Ca2+ pools blocked induction of JR genes by both wounding and JA, but not the induction of WR genes by wounding, but this effect could not be reproduced by increasing intracellular Ca2+ levels using ionophores. In addition, calmodulin antagonists blocked the expression of JR genes and up-regulated WR gene expression. Ca2+ and calmodulin seem to act downstream of both JA and the COI1 gene in the JA-dependent pathway, and downstream of reversible phosphorylation events that differentially regulate JA-dependent and JA-independent wound signal transduction pathways.
我们已将创伤和茉莉酸（JA）响应基因用作分子标记，以阐明拟南芥中创伤信号转导的途径。JA响应（JR）基因JR1、JR2和JR3受到创伤和JA的强烈诱导，而创伤响应（WR）基因WR3和酰基辅酶A氧化酶（ACO）仅受创伤诱导。吲哚美辛可阻断创伤后JR转录本的积累。然而，吲哚美辛既不影响这些基因受JA的诱导，也不影响创伤诱导的WR基因的表达，这表明JA合成仅在创伤依赖的JR基因诱导中是必需的，并且拟南芥中存在独立的JA依赖和JA非依赖的创伤信号转导途径。这两条途径受Ca2+和钙调蛋白的差异调节。细胞内Ca2+库的动员可阻断创伤和JA对JR基因的诱导，但不影响创伤对WR基因的诱导，不过使用离子载体提高细胞内Ca2+水平无法重现这种效应。此外，钙调蛋白拮抗剂可阻断JR基因的表达并上调WR基因的表达。Ca2+和钙调蛋白似乎在JA依赖途径中位于JA和COI1基因的下游，以及在差异调节JA依赖和JA非依赖创伤信号转导途径的可逆磷酸化事件的下游。
