Same same but different: Cluster architecture variation in five 'Pinot Noir' selection lines correlates with differential expression of three transcription factors and further growth related genes
Grapevine (Vitis vinifera L.) is an economically important crop that needs to comply with high quality standards for fruit, juice and wine production. Intense plant protection is required to avoid losses caused by fungal infections. Grapevine cultivars with loose cluster architecture enable to reduce protective chemical treatments due to their enhanced resilience against fungal infections such as Botrytis cinerea induced grey mold. A recent study identified transcription factor gene VvGRF4 as determinant of inflorescence structure in exemplary samples of loose and compact quasi-isogenic Pinot Noir clones. Here, we extended the analysis to 12 differently clustered Pinot Noir clones originating from five different clonal selection programs. Differential gene expression of these clones was studied in three different locations over three seasons in demonstrative vineyards. Two phenotypically contrasting clones were grown at all three locations and served for standardization of downstream analyses. Differential gene expression data were correlated to the phenotypic variation of cluster architecture sub-traits. A consistent differential gene expression of VvGRF4 in relation to loose clusters was verified over the different environments and in the extended set of Pinot Noir clones. In addition, 14 more genes with consistent expression differences between loosely and compactly clustered clones independent from season and location were identified. These genes show annotations related to cellular growth, cell wall extension, cell division and auxin metabolism. They include two more transcription factor genes.