conference schedule and program with abstracts - Horticulture ...
conference schedule and program with abstracts - Horticulture ...
conference schedule and program with abstracts - Horticulture ...
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P-38<br />
Characterization of a new hormone in grape <strong>and</strong> analysis of its influence on grape<br />
development processes<br />
A. Keren-Keiserman*, A. Lichter, A. Perl, A. Ogredovitch, S. Lavee, E. Or<br />
Institute of Plant Sciences, The Volcani Center, Bet Dagan, Israel<br />
*Corresponding author: ettilab@agri.gov.il<br />
Phytosulfokines (PSKs) are secreted, sulfated peptide hormones derived from larger prepropeptide<br />
precursors. They are required for the proliferation <strong>and</strong> differentiation of plant cells in<br />
tissue culture <strong>and</strong> also promote cellular longevity. Recently it was realized that PSKs are<br />
involved in the attenuation of stress response <strong>and</strong> healing of wound-activated cells. Redundancy<br />
was confirmed between both PSK's receptors <strong>and</strong> several PSKα genes <strong>and</strong> phenotypes were<br />
observed only after parallel mutagenesis of several paralogs. Proteolytic processing of<br />
preproPSK precursors is dependent on a subtilisin-like serine protease. Four paralogs, of PSK<br />
<strong>and</strong> one PSK receptor (VvPSKR) have been isolated from Vitis vinifera <strong>and</strong> the genes were<br />
characterized. The expression profiles of VvPSK1 <strong>and</strong> VvPSK5 were analyzed in different<br />
organs, at different developmental <strong>and</strong> physiological stages, <strong>and</strong> in dormant buds subjected to<br />
oxidative <strong>and</strong> cold stresses. Transcripts are detectable in all tissues in basal levels <strong>and</strong> are<br />
induced during flowering <strong>and</strong> at fruit set, <strong>and</strong> later at véraison. Both genes are also highly<br />
expressed during embryo development <strong>and</strong> in dormant buds treated <strong>with</strong> dormancy release<br />
agents. VvPSK1 <strong>and</strong> VvPSKR were over expressed in embryonic cells <strong>and</strong> regenerated plants of<br />
V. vinifera <strong>and</strong> also in Nicotiana tabacum plants. The transgenic plants did not exhibit<br />
observable phenotypes. However, in contrast to cells grown in the dark, transgenic callus grown<br />
under long-day conditions exhibited yellow coloration. To further study the function of PSK in<br />
grape, we have developed an inducible RNAi construct to knock-down all four paralogs of the<br />
gene. This gene knock-down experiment is still underway. Our results support the model of<br />
stress-activated transcription, resembling the findings in Oryza sativa (rice) <strong>and</strong> Arabidopsis,<br />
where both transcriptional <strong>and</strong> post-translational modification of PSK documented.<br />
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