| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1997: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1996: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
Plant defense reactions against pathogens such as fungi, bacteria, and viruses involve induced synthesis of low molecular weight compounds called phytoalexins. Biotic elicitors which are derived from the cell surface of pathogenic microbes as well as host plants tRIgger the defense response. It is considered that an elicitor molecule is combined with a plant membrane receptor, and that the complex activates a series of specific genes, resulting in the synthesis of phytoalexins. We have suggested that jasmonic acid functions as a signal transducer in the induction of biosynthesis of the phytoalexin momilactone A by the elicitor N-acetylchitoheptaose in suspension-cultured rice cells. To investigate mode of action of jasmonic acid in the rice cells, we attempted cDNA cloning of jasmonic acidresponsive genes. Three cDNA clones ( cRRJ1, cEEJ2, and cRRJ4 ) and one cDNA clone ( cRERJ1 ) were isolated by differential screening of cDNA libraries prepared from suspensioned-cultured rice cells t
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reated with 10-4 M of racemic jasmonic acid for 2 hours and 30 minutes, respectively. RRJ1 encodes a putative polypeptide that is homologous to enzymes catalyzing synthesis or metabolism of sulful-containing amino acids. RRJ2 encodes a putative polypeptide that is highly homologous to pyrvate decarboxylases from rice and maize, and probably contributes to aquirement of energy in rice cells under the anairoic condition. The putative polypeptide by RRJ4 is homelogous to members of old yellow enzyme superfamily biological functions of which remains to be clarified. RERJ1 encodes a putative polypeptide that contains a basic region/helix-loop-helix ( bHLH ) domain near the carboxyl terminus. Since bHLH proteins are ubiquitous transcription factors that have been found virtually all eukaryotes examined to date, RERJ1 might play one of important roles in the signal transduction pathway of jasmonic acid in he suspension-cultured cells. This is the first information on the presence of a transcription factor gene that is responsive to jasmonic acid. Less
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