Berry texture QTL and candidate gene analysis in grape ( L.).

Berry texture is a noteworthy economic trait for grape; however, the genetic bases and the complex gene expression and regulatory mechanism for the diverse changes in berry texture are still poorly understood. In this study, the results suggest that it is difficult to obtain high-mesocarp firmness (MesF) and high-pericarp puncture hardness (PPH) grape cultivars with high pericarp brittleness (PerB). The high-density linkage map was constructed using whole-genome resequencing based on 151 F individuals originating from intraspecific hybridization between the firm-flesh cultivar 'Red Globe' and soft-flesh cultivar 'Muscat Hamburg'. The total length of the consensus map was 1613.17 cM, with a mean genetic distance between adjacent bin markers of 0.59 cM. Twenty-seven quantitative trait loci (QTLs) for berry MesF, PPH, and PerB were identified in linkage groups (LGs) 1, 3, 4, 6, 8, 9, 10, 11, 14, 16, and 17, including twelve QTLs that were firstly detected in LGs 6, 11, and 14. Fourteen promising candidate genes were identified from the stable QTL regions in LGs 10, 11, 14, and 17. In particular, and refer to chromosome 17 and are two promising candidate genes for MesF and PPH, as the gene may increase pectin residue binding with WARK for high berry firmness maintenance and the allele for carrying the 'CC' and 'GA' genotypes at Chr17:1836764 and Chr17:1836770 may be associated with non-hard texture grape cultivars. In addition, real-time quantitative polymerase chain reaction (RT-qPCR) verification revealed that the promising candidate transcription factor genes , , , , and may regulate cell wall metabolism candidate gene expression for grape berry texture changes.