|Budget Amount *help
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1989: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1988: ¥1,600,000 (Direct Cost: ¥1,600,000)
Similarly to the cases of plant bacterial pathogen, such, as Pseudomonas savastanoi and Agrobacterium tumefaciens, plant fungal hyperplastic pathogen, Taphrina wiesneri, Taphrina deformans and Taphrina pruni, produced high concentrations of IAA and cytokinin that seems to result in disturbing the hormone balance in the host cells followed by the hyperplasia of plant cells.
In this research, we elucidated the IAA biosynthetic pathway of Taphrina wiesneri. and purified one of relative enzyme of this pathway to investigate the regulational mechanisms of IAA biosynthesis. Further, we obtained Iaa- mutants and carried out pulse field gel electrophoresis for the genetic analysis of the mutants.
1. <Biostnthetic pathway of IAA and their regulation> There are two biosynthetic pathway of IAA in Taphrina wiesneri, namely 1) from L-tryptophan (Trp), indole-3-pyruvic acid (IPA), indole-3-acetaldehyde (IAAL) to IAA, 2) indole-3-aceton-itrile (IAN) to IAA. Although tryptophan amino transferase (TATase
) which convertes Trp into IPA is uninducible, IAN nitrilase which :convertes IAN into IAA is inducible. One of the IAA biosynthetic pathways was regulated by the oxidation or reduction of IAA1, because in clofibric acid (CFA) mutant of Taphrina wiesneri (Iaa- mutant) IAA was not synthesized from IAA1, and indole-3-ethanol (IEOH) was accumulated.
2. <Purification of TATase> It was clarified that at least three TATase isozymes are present by the purification of these enzymes using arhmonium sulfate precipitation, gel filtration, DEAE ion exchange, and affinity chromatography.
3. <Selection of IAA- mutant> IAA deficient mutant was selected by the resistance against anti-auxin compound, CFA. In this mutant, IAA producibility was significant inhibited, and IEOH accumulation was observed instead of IAA. Therefore it was speculated that the treatment with CFA might have caused some mutation in gene encoding IAAL monooxigenase. In addition, we observed that chromosome III (a tentative name) was separated into two fragments by the pulse field gel electrophoresis. Less