QTL Mapping and Underlying Genes for Heat Tolerance in Grapevine (Rhine Riesling × Cabernet Sauvignon) under Field Conditions

Grapevine is one of the most widely cultivated perennial fruit crops in the world, with its economic relevance mainly related to wine production. Climate change, with global warming and increased frequency of intense phenomena, is greatly affecting viticulture and the wine sector. Thus, studying the genetic factors involved in grapevine response to high temperatures can help to improve vineyard management strategies and support plant breeding innovations. In this experiment, a mapping population (Rhine Riesling × Cabernet Sauvignon) was used to perform a genetic dissection of the physiological response to increased temperatures under vineyard conditions. Photosynthetic activity and stomatal dynamics were evaluated for three seasons during hot days at different plant developmental stages. Results of quantitative trait loci (QTL) analysis highlighted 26 genomic regions that consistently contribute to the eight tested traits. Candidate genes with supporting evidence, underlying QTL clusters with explained variance above 10%, are those associated with signal perception and transduction, protein homeostasis, osmoprotection, photosynthesis and response to radiation which are relevant mechanisms for plant heat acclimation. Within the stable chromosomal intervals identified by this exploratory analysis, other gene predictions emerged that may be tested for their involvement in grapevine resilience to increasing temperatures. The genetic architecture of quantitative traits linked to grapevine heat tolerance investigated under real field conditions, helps to define key targets for adapting an important traditional crop to environmental changes.