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Grapevine growing areas are increasingly affected by drought, which has greatly limited global wine production and quality. DEAD-box is one of the largest subfamilies of the RNA helicase family, and its members play key roles in the growth and development of plants and their stress responses. Previous studies have shown the potential of DEAD-box genes in the drought stress responses of Arabidopsisand tomato, rice, and other crop species. However, information about DEAD-box genes in grapevine remains limited. In this report, a total of 40 DEAD-box genes were identified in grapevine and their protein sequence characteristics and gene structures were analyzed. By comparing the expression profiles of VviDEADRHsin response to drought stress in different grapevine varieties, nine candidate genes (VviDEADRH10c, -13, -22, -25a, -25b, -33, -34, -36, and -39) were screened based on expression profiling data. Combined with qRT-PCR results, VviDEADRH25awas selected for functional verification. Heterologous overexpression of VviDEADRH25ain Arabidopsisshowed the transgenic plants were more sensitive to drought stress than the control. Both electrolyte permeability and malondialdehyde content were significantly increased in transgenic plants, whereas the chlorophyll content and superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) enzyme activities were significantly decreased. Furthermore, VviDEADRH25a-overexpressing plants showed down-regulated expression levels of several drought stress-related marker genes, namely AtCOR15a, AtRD29A, AtERD15, and AtP5CS1, which indicated that they participated in the drought stress response. In summary, this study provides new insights into the structure, evolution, and participation of DEAD-box RNA helicase genes in the response to drought stress in grapevines.

Non-conventional peptides (NCPs), which are peptides derived from previously unannotated coding sequences, play important biological roles in plants. In this study, we used peptidogenomic methods that integrated mass spectrometry (MS) peptidomics and a six-frame translation database to extensively identify NCPs in grape. In total, 188 and 2021 non-redundant peptides from the Arabidopsis thalianaand Vitis viniferaL. protein database at Ensembl/URGI and an individualized peptidogenomic database were identified. Unlike conventional peptides, these NCPs derived mainly from intergenic, intronic, upstream ORF, 5′UTR, 3′UTR, and downstream ORF regions. These results show that unannotated regions are translated more broadly than we thought. We also found that most NCPs were derived from regions related to phenotypic variations, LTR retrotransposons, and domestication selection, indicating that the NCPs have an important function in complex biological processes. We also found that the NCPs were developmentally specific and had transient and specific functions in grape berry development. In summary, our study is the first to extensively identify NCPs in grape. It demonstrated that there was a large amount of translation in the genome. These results lay a foundation for studying the functions of NCPs and also provide a reference for the discovery of new functional genes in grape.