Transcription factors regulating uspA genes in Catharanthus roseus

Genome-Wide Analysis of the Universal Stress Protein Gene Family in Blueberry and Their Transcriptional Responses to UV-B Irradiation and Abscisic Acid

Universal stress proteins (USPs) play essential roles in plant development, hormonal regulation, and abiotic stress responses. However, the characteristics and functional divergence of USP family members have not been studied in blueberry (Vaccinium corymbosum). In this study, we identified 72 VcUSP genes from the Genome Database for Vaccinium. These VcUSPs could be divided into five groups based on their phylogenetic relationships. VcUSPs from groups Ⅰ, Ⅳ, and Ⅴ each possess one UspA domain; group Ⅰ proteins also contain an ATP-binding site that is not present in group Ⅳ and Ⅴ proteins. Groups Ⅱ and Ⅲ include more complex proteins possessing one to three UspA domains and UspE or UspF domains. Prediction of cis-regulatory elements in the upstream sequences of VcUSP genes indicated that their protein products are likely involved in phytohormone signaling pathways and abiotic stress responses. Analysis of RNA deep sequencing data showed that 21 and 7 VcUSP genes were differentially expressed in response to UV-B radiation and exogenous abscisic acid (ABA) treatments, respectively. VcUSP41 and VcUSP68 expressions responded to both treatments, and their encoded proteins may integrate the UV-B and ABA signaling pathways. Weighted gene co-expression network analysis revealed that VcUSP22, VcUSP26, VcUSP67, VcUSP68, and VcUSP41 were co-expressed with many transcription factor genes, most of which encode members of the MYB, WRKY, zinc finger, bHLH, and AP2 families, and may be involved in plant hormone signal transduction, circadian rhythms, the MAPK signaling pathway, and UV-B-induced flavonoid biosynthesis under UV-B and exogenous ABA treatments. Our study provides a useful reference for the further functional analysis of VcUSP genes and blueberry molecular breeding.

Genome-wide analysis of the Universal stress protein A gene family in Vitis and expression in response to abiotic stress

Universal Stress Protein A (USPA) plays critical roles in the regulation of growth, development and response to abiotic stress in plants. To date, most research related to the role of USPA in plants has been carried out in herbaceous models such as Arabidopsis, rice and soybean. Here, we used bioinformatics approaches to identify 21 USPA genes in the genome of Vitis vinifera L. Phylogenetic analysis revealed that VvUSPAs could be divided into eight clades. Based on predicted chromosomal locations, we identified 16 pairs of syntenic, orthologous genes between A. thaliana and V. vinifera. Further promoter cis-elements analysis, together with identification of potential microRNA (miRNA) binding sites, suggested that at least some of the VvUSPAs participate in response to phytohormones and abiotic stress. To add support for this, we analyzed the developmental and stress-responsive expression patterns of the homologous USPA genes in the drought-resistant wild Vitis yeshanensis accession 'Yanshan-1' and the drought-sensitive Vitis riparia accession 'He'an'. Most of the USPA genes were upregulated in different degrees in the two genotypes after drought stress and exposure to ethephon (ETH), abscisic acid (ABA) and methyl jasmonate (MeJA). Individual USPA genes showed various tissue-specific expression patterns. Heterologous expression of five selected genes (VvUSPA2, VvUSPA3, VvUSPA11, VvUSPA13 and VvUSPA16) in Escherichia coli (E. coli) enhanced resistance to drought stress. Our study provides a model for mapping gene function in response to abiotic stress and identified three candidate genes, VvUSPA3, VvUSPA11 and VvUSPA16, as regulators of drought response in V. vinifera.