Quantitative trait loci for the response to gibberellic acid of berry size and seed mass in tablegrape ( V itis vinifera L.).

Background and Aims Bioactive gibberellins are commonly applied to increase the size of berries in seedless tablegrapes. The genetic determinants for the response of berry size to gibberellic acid ( GA₃) were investigated in a progeny (n = 137) of Ruby Seedless × Sultanina. Methods and Results Seed and berry size-related traits were measured at harvest (18° Brix). Heritability was high (∼79%) for all traits under study, especially seed dry mass (>90%). All these traits responded to GA₃ and showed interaction between genotype and treatment (g × GA₃). Based on quantitative trait loci ( QTL) analysis and the grapevine reference genome, we identified about 200 annotated genes located in the corresponding confidence intervals in linkage groups 2 and 18. Nineteen of these genes were selected for further characterisation because of their possible participation in g × GA₃. Conclusions The response to GA₃ has an important genetic basis which is given by QTLs localised on linkage groups 2 and 18. Under GA₃ treatment, the seed loses its genetic control on berry size given by its major QTLs, indicating a possible interaction between this genetic determinant and GA₃. Despite the masking effect, VvAGL11 is associated with the intensity of the response to GA₃. Significance of the Study These results indicate the complex role of g × GA₃ at the genetic level in the control of berry size. [ABSTRACT FROM AUTHOR]