PS 33-141 - Variation in leaf venation traits across grape (Vitis vinifera) varieties: the influence of domestication and consequences for Leaf Economics traits.

Background/Question/Methods

Leaf venation traits vary widely among plant species, and have implications for plant functions and responses to environmental change. Climate conditions correlate strongly with leaf venation patterns, such that leaves adapted to higher temperatures will tend towards features that allow for improved water use efficiency, including increased vein width and density, defined as vein length per unit leaf area. Existing studies on the causes and consequences of venation trait variation primarily focus on quantifying interspecific variation among wild plants. Fewer studies have evaluated within-species variation in venation traits of crops, or how these traits differ in wild plants vs. crops as a result of domestication. We assess these gaps using microscopy and gas exchange to quantify the causes and implications of variation in vein density, width, and other key venation traits, in six grapevine (Vitis vinifera) varieties and their wild congener (Vitis riparia), in the Niagara Region, Canada. With this dataset, we examined if intraspecific variation in leaf venation traits are governed by genetic factors, or by a phenotypic response to environmental conditions. We also tested if leaf venation traits are influenced by artificial selection, and how intraspecific variation in venation traits affects leaf physiological, morphological, and chemical traits.

Results/Conclusions

Leaf venation traits, notably vein density and width, were expected to differ among V. vinifera varieties, with variance partitioning indicating that variety identity explained a larger proportion of trait variation than local environmental conditions. Based on preliminary data, red grape varieties (Cabernet Sauvignon, Merlot, Syrah, Pinot Noir) expressed lower average vein density; a trait correlated with decreased water-use and comparatively lower photosynthetic rates. In comparison, white grape varieties (Chardonnay, Pinot Gris) expressed higher average vein density; correlated with higher photosynthetic rates and water-use. Domesticated plants expressed higher vein density, indicating greater photosynthetic rates but increased water-use in cultivated varieties compared to wild V. riparia. Our findings point to the role that intraspecific variation in leaf venation traits plays in influencing plant and crop responses to environmental change, and also highlight how artificial selection has influenced leaf venation traits over the course of crop domestication.