Ectopic expression of MAP kinase inhibits germination and seedling growth in transgenic rice

Abstract

Jasmonic acid (JA) inhibits seed germination and post-germination growth. We previously generated transgenic rice plants that overexpress wound-inducible MAP kinase from pepper. The transgenic rice plants accumulated about three times more JA than did the wild-type. The transgenic rice seeds required two more days to germinate, as compared to the wild-type, and shoot and root growth was inhibited. The root and shoot length of transgenic plants were comparable to those of the wild-type treated with 10 μM JA. In addition, the transcription level of storage proteins, such as prolamin and glutelin, decrseased more slowly in transgenic lines than in the wild-type during germination. MAP kinase activity was clearly enhanced in the embryos of transgenic rice plants during germination. The inhibition of the germination and growth of transgenic rice plants was attributed to the overexpression of the MAP kinase transgene, which resulted in a subsequent increase in both MAP kinase activity and JA synthesis.