Mapping the genetic architecture of grapevine bud growth-cycling quantitative traits

In a changing climate, the timings of vine growth resumption and cessation are critical parameters driving sustainable production. The underlying genetic architecture of growth cycling was determined by using an F₂ wine-grape mapping population to identify quantitative trait loci (QTL) for traits related to growth and growth cessation. These included: growth resumption in fully chilled vines (days to bud break, expanded shoot, and 10-node shoot, and number of summer laterals), cane maturation (number of nodes of periderm), and growth cessation in response to decreasing photoperiod (tip abscission). Phenotype data were collected on vines grown under greenhouse conditions in consecutive years. QTL analysis was conducted using composite interval mapping, phenotypes for 109 individuals and a genetic map with 1449 single-nucleotide polymorphism (SNP) markers across 19 linkage groups. Multiple QTL were identified for individual traits, with QTL mapping repeatedly to linkage groups 11, 13, and 18. Haley-Knott regression multi-QTL modeling was used to identify significant QTL. Resultant models accounted for ≥56% of the variation associated with growth resumption phenotypes, 57% of the variability associated with periderm development and 34% of the variation associated with growth cessation. Clarifying the genetic relationship in these complex growth-cycling traits provides information needed to identify key genes and generate markers for marker-assisted selection of sustainable cultivars under changing climatic conditions.