Aj. Bais et al., The molecular regulation of stilbene phytoalexin biosynthesis in Vitis vinifera during grape berry development (vol 27, pg 425, 2000), AUST J PLAN, 27(7), 2000, pp. 723A-433
The molecular regulation of stilbene phytoalexin biosynthesis in developing
Vitis vinifera L. grape berries was investigated using a UV induction syst
em. Berries were collected at 1, 5, 10 and 16 weeks post-flowering from the
cultivars Shiraz, Semillon, Cabernet Sauvignon and Chardonnay and the skin
s analysed for resveratrol production following irradiation with UV-C light
. The rate and maximal level of resveratrol accumulation increased markedly
in berries sampled from 1-5 weeks post-flowering and then dramatically dec
lined in maturing berries sampled from 10-16 weeks post-flowering in all cu
ltivars. In berries sampled at 1 and 5 weeks post-flowering, maximal levels
of resveratrol accumulation were recorded at incubation periods of 24 and
48 h respectively whereas maximal resveratrol levels were not recorded in w
eek 16 berry skins until 72 h after UV-treatment. Gene expression analysis
indicated that stilbene synthase (STS) mRNA accumulated within 4-8 h of UV
treatment in berries sampled at 1 and 5 weeks post-flowering, but did not i
ncrease in week 16 berries until 24-48 h following UV-irradiation. Furtherm
ore, the overall level of STS gene expression declined in berries sampled 1
0-16 weeks post-flowering. The results demonstrate that inducible stilbene
accumulation in ripening grape berries is highly regulated at the level of
STS gene transcription. This decline in inducible STS gene expression may b
e a major factor contributing to the increased susceptibility of ripening g
rape berries to Botrytis cinerea infection.