据此间报道，在3月31日的PNAS（《美国科学院院刊》）网络版上公布了由中国农业大学植物生理和生物化学国家重点实验室、美国密苏里州大学和明尼苏达州大学的研究人员合作进行的一项新研究。研究发现一种真菌应答MAPK（一种激酶）级联调节着模式植物拟南芥中的植物抗毒素生物合成过程。这篇文章的通讯作者是美国密苏里大学的华人学者Shuqun Zhang，第一作者是我校生物学院任东涛教授。
MAPK3和MAPK6是两种拟南芥分裂活化蛋白激酶（MAPK）。植物对病原的识别能致MAPK3和MAPK6迅速激活。研究人员在这篇新文章中报告：拟南芥中一种重要的植物抗毒素——camalexin受到MAPK3/MAPK6级联的调节。活泼的上游MAPK激酶（MAPKK）或MAPKK激酶（MAPKKK）的表达引发的MAPK3/MAPK6激活足以诱导在没有病原攻击时诱导camalexin的合成。
研究发现，由灰霉病菌触发的植保素camalexin的诱导是MAPK3/MAPK6活化的序幕，并且会因MAPK3和MAPK6级联处于PHYTOALXIN DEFICIENT2（PAD2）和PAD3的上游，但独立于PAD1和PAD4，或处于其下游；MAPK3/MAPK6激活后的camalexin诱导合成则是Trp（色胺酸）生物合成途径中多基因编码酶迅速协同上调的序幕。
这些研究结果表明，MAPK3/MAPK6级联在病因感染后通过对生物合成基因的转录调节来调控camalexin的合成。
生物谷推荐原始出处：
PNAS published March 31, 2008, 10.1073/pnas.0711301105
A fungal-responsive MAPK cascade regulates phytoalexin biosynthesis in Arabidopsis
Dongtao Ren*,, Yidong Liu, Kwang-Yeol Yang,, Ling Han, Guohong Mao, Jane Glazebrook, and Shuqun Zhang,¶
*State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, China; Department of Biochemistry, University of Missouri, Columbia, MO 65211; and Department of Plant Biology and Center for Microbial and Plant Genomics, University of Minnesota, St. Paul, MN 55108
Edited by Roger N. Beachy, Donald Danforth Plant Science Center, St. Louis, MO, and approved February 14, 2008 (received for review November 29, 2007)
Abstract
Plant recognition of pathogens leads to rapid activation of MPK3 and MPK6, two Arabidopsis mitogen-activated protein kinases (MAPKs), and their orthologs in other species. Here, we report that synthesis of camalexin, the major phytoalexin in Arabidopsis, is regulated by the MPK3/MPK6 cascade. Activation of MPK3/MPK6 by expression of active upstream MAPK kinase (MAPKK) or MAPKK kinase (MAPKKK) was sufficient to induce camalexin synthesis in the absence of pathogen attack. Induction of camalexin by Botrytis cinerea was preceded by MPK3/MPK6 activation, and compromised in mpk3 and mpk6 mutants. Genetic analysis placed the MPK3/MPK6 cascade upstream of PHYTOALEXIN DEFICIENT 2 (PAD2) and PAD3, but independent or downstream of PAD1 and PAD4. Camalexin induction after MPK3/MPK6 activation was preceded by rapid and coordinated up-regulation of multiple genes encoding enzymes in the tryptophan (Trp) biosynthetic pathway, in the conversion of Trp to indole-3-acetaldoxime (IAOx, a branch point between primary and secondary metabolism), and in the camalexin biosynthetic pathway downstream of IAOx. These results indicate that the MPK3/MPK6 cascade regulates camalexin synthesis through transcriptional regulation of the biosynthetic genes after pathogen infection.
