Characterizing Root System Architecture Traits for Drought Tolerance in Grapevine Rootstocks
Sam Dudley,* Isaac K. Uyehara, Andrew McElrone,
and Megan K. Bartlett
*University of California, Davis, 750 Anderson Rd., Davis, CA,
95616 (sdudley@ucdavis.edu)
To reduce the effects of climate change on viticulture, breeding more drought-tolerant rootstocks is a promising, but difficult, strategy due to limited information on traits and genes of interest. Our goal is to use an F1 population produced from a drought-tolerant and a drought-sensitive rootstock (110 Richter × 101-14 MGT) to identify molecular markers for root system architecture (RSA) traits in grapevine. Neutron radiography is an imaging technique that can non-destructively visualize entire small root systems. We subjected plants to two-week dry-down and rewatering treatments and used neutron radiography and new semi-automated root classification software to measure RSA. Here, we present preliminary results for a subset of 45 genotypes. We will complete measurements across the entire population and use genotyping by sequencing (GBS) to link RSA traits to molecular markers by next summer.
The 45 genotypes varied significantly (p < 0.001) in nearly all RSA traits, including total root length, mean root angle, aspect (total horizontal/vertical extent), root growth rate, and change in depth during drought. Roots were significantly steeper rooted and thicker in 110 Richter than 101-14 MGT, suggesting these are especially important traits for drought tolerance. Across genotypes, a more vertical aspect was correlated with a steeper root angle (r2 = 0.47) and thicker mean root diameter (r2 = 0.09), but independent of root system size and fibrosity (root system length/# of tips) (p > 0.05). Altogether, these findings suggest that this population is well-suited to identify genetic associations with RSA, and that selecting for a more vertical aspect, steeper root angles, and thicker roots could enhance drought tolerance in grape rootstocks, though more work is needed to evaluate how these phenotypes perform under field conditions. Genetic associations are pending current experimentation results.
Funding Support: California Department of Food and Agriculture
