Ishiga Yasuhiro, Funato Akiko, Tachiki Tomoyuki, Toyoda Kazuhiro, Shiraishi Tomonori, Yamada Tetsuji, Ichinose Yuki
Laboratory of Plant Pathology and Genetic Engineering, Faculty of Agriculture, Okayama University, Tsushima-naka, 1-1-1 Okayama, 700-8530 Japan.
Plant Cell Physiol. 2002 Oct;43(10):1210-20. doi: 10.1093/pcp/pcf144.
Suppressors produced by Mycosphaerella pinodes are glycopeptides to block pea defense responses induced by elicitors. A clone, S64, was isolated as cDNA for suppressor-inducible gene from pea epicotyls. The treatment of pea epicotyls with suppressor alone induced an increase of S64 mRNA within 1 h, and it reached a maximum level at 3 h after treatment. The induction was not affected by application of the elicitor, indicating that the suppressor has a dominant action to regulate S64 gene expression. S64 was also induced by inoculation with a virulent pathogen, M. pinodes, but not by inoculation with a non-pathogen, Ascochyta rabiei, nor by treatment with fungal elicitor. The deduced structure of S64 showed high homology to 12-oxophytodienoic acid reductase (OPR) in Arabidopsis thaliana. A recombinant protein derived from S64 had OPR activity, suggesting compatibility-specific activation of the octadecanoid pathway in plants. Treatment with jasmonic acid (JA) or methyl jasmonic acid, end products of the octadecanoid pathway, inhibited the elicitor-induced accumulation of PAL mRNA in pea. These results indicate that the suppressor-induced S64 gene expression leads to the production of JA or related compounds, which might contribute to the establishment of compatibility by inhibiting the phenylpropanoid biosynthetic pathway.
由豌豆小球腔菌产生的抑制因子是糖肽，可阻断激发子诱导的豌豆防御反应。从豌豆上胚轴中分离出一个克隆体S64，作为抑制因子诱导基因的cDNA。单独用抑制因子处理豌豆上胚轴会在1小时内诱导S64 mRNA增加，处理后3小时达到最高水平。这种诱导不受激发子应用的影响，表明抑制因子在调节S64基因表达方面具有主导作用。接种强致病性病原体豌豆小球腔菌也可诱导S64，但接种非病原体菜豆壳二孢菌或用真菌激发子处理则不能诱导。推导的S64结构与拟南芥中的12-氧代植物二烯酸还原酶（OPR）具有高度同源性。源自S64的重组蛋白具有OPR活性，表明植物中十八烷酸途径存在相容性特异性激活。用十八烷酸途径的终产物茉莉酸（JA）或茉莉酸甲酯处理可抑制激发子诱导的豌豆中苯丙氨酸解氨酶（PAL）mRNA的积累。这些结果表明，抑制因子诱导的S64基因表达导致JA或相关化合物的产生，这可能通过抑制苯丙烷生物合成途径有助于建立相容性。
