New Stable QTLs for Berry Firmness in Table Grapes

Abstract

Berry firmness is one of the most important quality traits in table grape production and, consequently, a key aspect for table grape breeding programs. To identify the genes determining the berry firmness in grapes, a progeny of Ruby Seedless x Sultanina (n = 137) was evaluated during three consecutive seasons. Results showed that even though the heritability was similar to 90%, season had an important effect on this trait. Quantitative trait loci (QTL) analysis and genetic mapping showed that the determinants for this trait are distributed in linkage groups 8 and 18. This is the first time that a stable QTL for berry firmness across seasons has been identified on linkage group 8. This QTL is mainly given by a male allelic and additive effect. Together, these two QTLs explained similar to 27.6% of the phenotypic variance, with confidence intervals of up to 10 cM. Among the tens of genes found in these two QTLs, we highlight a cation/calcium exchanger, a xylosyltransferase, a probable cellulose synthase, and a putative invertase. This study shows that berry firmness has a clear genetic basis. These results could also be used for the development of markers to assist table grape breeding.FONDECYT-Chile 112088

Construction of a High-Density Genetic Map and Mapping of Firmness in Grapes (Vitis vinifera L.) Based on Whole-Genome Resequencing

“…Moreover, there were a certain number of "super-parent" individuals in the population, and berry firmness in the offspring showed continuous variation. The distribution was close to the normal distribution, indicating that this trait is quantitatively inherited and controlled by multiple genes, which is consistent with previous studies [6,50].…”

“…The genetic positions were 67.81-68.29 cM, 59.64-60.60 cM, and 57.23-61.56 cM, and corresponded to the physical positions 26.58-27.20 Mb, 25.03-28.59 Mb, and 24.64-28.59 Mb of chromosome 18, respectively. These QTLs are similar to those found by Carreño et al [6] and Correa et al [50] on LG18. The physical position of the SNPs did not coincide with genetic position in this study, which was likely attributed to errors in the alignment of reference genome sequence, as well as different microstructures on chromosomes [10].…”

“…The QTL on chromosome 8 was located between the markers UDV125 and VMCNG2H2 and explained approximately 15.6% of the phenotypic variation, and the QTL on chromosome 18 was located between VVIN16 and VVCS1E103N17FM1 and explained approximately 12% of the phenotypic variation. This was the first report of a QTL for grape berry firmness that was stable in different seasons [50]. In this study, we identified three QTLs related to berry firmness located on LG 18, which explained 21.5%-28.6% of the phenotypic variation.…”

“…The first study for QTLs associated with berry firmness in table grapes found seven genomic regions on linkage groups (LGs) 1,4,5,9,10 (bottom region), 13, and 18, which individually explained up to 19.8% of the total phenotypic variance [6]. A second QTL study identified firmness determinants distributed in LGs 8 and 18, which explained 27.6% of the phenotypic variance, with confidence intervals up to 10 cM [50]. A third study using 98 F1 individuals from a Vitis labruscana × V. vinifera cross reported two QTLs for firmness that were located on LGs 3 and 10, with the former being more stable [18].…”

Development and Use of Biotechnology Tools for Grape Functional Analysis

“…The study of the genetic control of major agronomic traits in grapevine using QTL analysis allowed the elucidation of traits such as seedlessness and berry weight [12,18,[21][22][23]; berry phenolic composition [24][25][26][27][28]; aroma [29,30]; berry firmness [31,32]; fertility [9,33]; flower hermaphroditism [34]; cluster architecture [35]; pathogen resistance [34,[36][37][38]; plant phenology [39,40]; and adaptation to abiotic stresses [41] and to climate change [42]. Despite several of the reports allowed the identification of candidate sequences, just few of them have finally characterized the genes responsible for a particular function or trait.…”