14.02.2014 Views

conference schedule and program with abstracts - Horticulture ...

conference schedule and program with abstracts - Horticulture ...

conference schedule and program with abstracts - Horticulture ...

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

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 />

114


Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!