Chemical disease-resistance mechanism during seedling stage

点击翻译按钮获取中文摘要

The main aim of this science program is to understand the production and metabolisms as well as disease-resistant mechanism of 5-alkylresorcinols as phytoanticipins during rice seedling stage.1. Disease-resistance effects of ARs : In vitro conidia-germination and mycelia-growth tests using rice-blight disease fungus (Magnaporthe grisea) and an in vivo infection test suggested that ARs play a some role on disease-resistant mechanism as a phytoanticipin.2. ARs metabolisms : New two metabolites (AR-A8 and AR-A10) of ARs were isolated from etiolated rice-seedlings that were irradiated for 2 days, and their structures determined based on GC-MS and ^1H-NMR spectra. These metabolites seemed to be produced via oxidative double-bond cleavage of unsaturated carbon-chains in ARs (AR15 : 1 , AR17 : 1 s, AR17 : 2). From the finding of AR-A10 metabolite, a new homolog of AR17 : 1 , 5-(10'-heptadecenyl) resorcinol was identified.3. Classification of rice varieties based on AR-homolog composition : AR-homo log composition and their amounts were examined for 13 varieties of Japonica-type rices. The homolog compositions had a close relationship to disease- resistant-gene types. Especially, the composition of 3 varieties that produce a trace amount of ARs largely different from those with the other domestic- and indica-type genes.4. ARs biosynthesis : In efficient 5-alkylresorcinol-producing, etiolated rice seedlings, feedings of odd-number fatty acid ester substrates increased only the homologs expected from the predicted ARs biosynthetic pathway. In addition, the dodecyl homolog that was biosynthesized from [^<13>C]-labeled substrate obviously showed that fatty acid unit acted as a direct precursor and formed the side-chain moiety of 5-alkylresorcinol via the predicted biosynthesis pathway.