Identification and expression analysis of ERECTA family genes in grape (Vitis vinifera L.).

BACKGROUND: ERECTA family (ERf) genes are found in many dicots and monocots, and play important roles in plant developmental processes and stress responses. However, there is little known on ERf genes in grape (Vitis vinifera L.).
OBJECTIVES: The primary objective of this study was to identify the ERf genes in grape, and to analyze their expression profiles in different organs, during development, and in response to hormone treatments and abiotic/biotic stresses.
METHODS: ERf protein sequences of dicots were aligned in the grape genome (V. vinifera cv. Pinot Noir, PN40024, 12X) with Blast server. The locus tags obtained were inputted in NCBI to retrieve corresponding nucleotide and protein accession numbers. The subcellular localization experiment was performed by the transient expression of VvERECTA-GFP and VvERL2-GFP in mesophyll protoplasts of Arabidopsis. The expression levels of ERf genes in grape leaves were detected by qRT-PCR after hormone treatments and abiotic/biotic stresses.
RESULTS: We first identified the ERf genes in the grape genome, including VvERECTA and VvERL2. Their cDNA full-length sequences were obtained with the accession numbers MG601756 and MG601757. The result of subcellular localization indicated that the fusion proteins of VvERECTA and VvERL2 were localized in the plasma membrane. There were four conserved domains identified in VvERECTA and VvERL2, including a LRRNT-2, a LRR, a transmembrane and a protein kinase domain. The grape ERf genes expressed highly in young aboveground organs. As grape leaves or berries becoming mature, VvERECTA expressed in a declining trend. The transcript abundance of VvERL2 decreased during leaves development, but showed no significant differences during berries development. The hormone treatments of ABA, SA, MeJA and BR could induce the expression of VvERECTA and VvERL2. The treatments of heat, drought, downy and powdery mildew significantly increased the expression levels of the grape ERf genes.
CONCLUSION: The grape ERECTA gene family might play crucial roles in response to abiotic and biotic stresses. We provide the first description of the grape ERf genes and the most comprehensive analysis of their expressions in different biological processes.