| Research Abstract |
Effects of elicitor and suppressor produced by a pea pathogen, Mycosphaerelia pinodes, were examined on the signal transduction and the regulation of the genes encoding PAL and CHS in pea active defense responses.
1. Mode of action on plasma membrane (PM) ATPase. Suppressor inhibits PM-ATPase not only from pea but also from other plant species tested in in vitro assay, but cytological studies showed that it specifically inhabits only pea PM-ATPase. Moreover, orthovanadate, a non-specific inhibitor for PMATPase, functions in delaying the induction of the expression of PAL and CHS in a manner very similar to a fungal suppressor.
2. Effects on PM phosphoinisitides (PI) metabolisms. The phosphorylation of PIP and PIP2 by lipid kinase was stimulated by the treatment with elicitor, but it was distinctively suppressed in the concomitant presence of suppressor.
3. Structure of PAL genes and the control of the gene expression. Structure and gene organization of the two members of PAL gene (PSPALI
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and PSPAL2) in a small multigene family were determined, and the accumulation of the transcripts of each member in the tissues was examined using sequence specific probe. High level of the accumulation of both transcripts'was observed in roots and the lower portion of the stems, but very little in other organs, which suggests that PSPALI and PSPAL2 may contain ciselement responsible for tissue specific expression particularly in roots. Furthermore, the sequentially deleted promoter fragment of PSPALI connected to a plant expression vector containing the reporter gene was introduced into pea protoplasts by electroporation, and induction by elicitor and suppression by orthovanadate was examined. Cis- elei-nent responsible for these regulations exists between -340100 of PSPALI.
4. Structure and organization of CHS gene. Pea CHS genes (PSCHSI, PSCHS2) form a cluster in a tandem repeat with a spacer, and an identical 31 bp sequence containing, the consensus motif of box I locates 5'-upstream from the putative TATA box of both CHS genes. Less
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