Can Water-Saving Traits Reduce Grapevine Irrigation Demand Without Compromising Yield and Quality? AVF Project #2024-2811.

Summary of Progress:

Climate change is expected to increase irrigation demand at the same time as reducing irrigation supply, and developing plant material with lower irrigation needs is crucial to adapt the grape industry to future conditions.  Previous work suggests that altering stomatal traits to reduce maximum gas exchange rates or reduce gas exchange more strongly in response to water stress would increase grapevine water-use efficiency without compromising the carbon supply for growth and ripening.  The goal of our project is to use genetic engineering to generate plant material with water-saving stomatal traits, while leaving the rest of the genome intact, to experimentally test the effects of these traits on yield and ripening in economically important grape cultivars.  We will target four genes with known effects on stomatal traits and gas exchange for overexpression (OST1 and CLE25) or under expression (knock-out mutations) (EPFL9 and EVE).  We will conduct these transformations in Thompson Seedless, as a table grape with a high success rate for genetic transformation, and Chardonnay, as the most-produced wine grape in California, including in hot, water-limited regions.  Last year, we completed the bioinformatics work needed for the plant transformations and created plasmids with the target mutations for the overexpressed genes.  The Cantu lab sequenced the Thompson Seedless genome and identified homologues for the four target genes in the two grape varieties and supplied the mutant plasmids for the overexpression mutants (OST1 and CLE25) to the UC Davis Plant Transformation facility to create the transformed plant material.  This year, the Cantu lab generated plasmids for the knock-out mutants (EPFL9 and EVE), which are more complex than the overexpression mutants, and submitted these plasmids to the Transformation facility.  We are now waiting for the facility to generate our plant material.