87 根寄生雑草 Striga hermonthica の発芽応答性遺伝子の解析

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Striga hermonthica (Del.)Benth. is a root parasitic weed that reduces the yield of important cereals in semi-arid Sub Saharan Africa. Germination of the parasite seeds, induced by a synthetic germination stimulant GR24, was inhibited by AVG, an inhibitor of ACC synthase activity, and 1-MCP, a competitive inhibitor of ethylene receptor. Inhibition by AVG was restored by ACC, the immediate ethylene precusor, whereas that by 1-MCP was not. These results suggest that ethylene biosynthesis is involved in S.hermonthica germination. RNAs, isolated from GR24- or water-treated seeds, were used for PCR-based amplification of DNA fragments encoding the ACC synthase-active site domain. Two ACC synthas genes named SH-ACS1 and SH-ACS2 were obtained. Both genes were expressed irrespective of the treatment. However, northern blot analysis showed that expression of SH-ACS1 exhibited a temporal change, after GR24 treatment, which was in accord with that of ethylene evolution from the seeds. Consequently, it is concluded that SH-ACS1 gene plays a crucial role in regulating germination of S.hermonthica seeds.
植物化学調節学会の論文
1999-10-01