|Budget Amount *help
¥7,300,000 (Direct Cost : ¥7,300,000)
Fiscal Year 1993 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1992 : ¥6,300,000 (Direct Cost : ¥6,300,000)
There is a turning point in the process of differentiation of Zinnia mesophyll cells into tracheary elements. At the point, cells enter the irreversible process of differentiation. I here studied the irreversible process biochemically and molecular biologically. First, I tried to isolate molecular markers associated with the secondary wall formation. As a result, cDNAs for tubulin (ZTUB1-3). phenylalanine ammonia-lyase(ZPAL1-4) and an isotype ofwall-bound peroxidases(ZPO-C) were isolated. Transcripts corresponding to ZPO-C were found to be expressed specifically in differentiating cells and transiently just before lignin deposition, indicating that this gene was a good marker of irreversible process. Second, a cDNA for cysteine protease which was involved in autolysis was also isolated. The transcripts for this cDNA also showed a transient and specific expression pattern. The comparison of upstream regions of ZPO-C and cycteine protease genes will cast a new light on gene regulation in the irreversible process. Third, I tried isolate cDNAs corresponding to transcripts that were expressed at the turing point of differentiation and succeeded in the isolation of such cDNA clones designed as TED2-4. In situ hybridization of Zinnia seedings with TED2-4 cDNAs as probes revealed that TED3, 4 and 2 were expressed in cells that had a potency to differentiate to tracheary elements, xylem cells, and xylem or phloem cells, respectively.