Structural and functional analyses of the GRAS and LOB gene family in grapevine indicate a role of GRAS and LOB proteins in the control of grape ripening and stress responses

Abstract

GRAS and LOB are transcription factors involved in many processes of plant growth and development as well as abiotic and biotic stress responses. However, little information is available concerning these genes families in grapevine (Vitis viniferaL.). We performed a model curation of genes identified in the latest genome annotation leading to the identification of 52 GRAS genes and 50 LOB genes. Gene models were improved and new genes were identified that could be grapevine-or woody-plant specific. Phylogenetic analysis showed that GRAS genes could be classified into 13 groups and LOB genes into two classes. Multiple sequence alignment showed typical GRAS domain in the proteins and new motifs were also described. In LOB domain proteins the zinc finger-like domain was conserved; the leucine zipper-like motif was absent in class II. Expression patterns across a variety of tissues and upon abiotic and biotic conditions revealed possible divergent functions of GRAS and LOB genes in grapevine development and stress responses. Promoter analysis of LOB genes revealed several transcription factor binding sites associated with development and abiotic and biotic stress responses. Candidate genes that might constitute transcriptional regulators of grape ripening were identified. Altogether this study provides robust candidate genes for future functional analysis aiming at improving the quality of fleshy fruits.