Abstract
BACKGROUND: The short strand-related sequence (SRS) gene family is a class of plant-specific transcription factors related to a group of genes known as the short internode (SHI) or SRS/STY gene family, which plays important roles in regulating plant growth and development and stress responses. Although the SRS genes have been studied in many plants, in cucurbit crops, they have thus far only been identified in cucumber. METHODS: In the Cucurbitaceae database from melon (Cucumis melo), cucumber (Cucumis sativus), watermelon (Citrullus lanatus), bottle gourd (Lagenaria siceraria), wax gourd (Benincasa hispida), moschata pumpkin (Cucurbita moschata), and pumpkin (Cucurbita maxima), a total of 60 SRS genes were identified in seven Cucurbitaceae crops, which were classified into three subfamilies. RESULTS: The same subfamily showed conserved motifs and gene structures. The differences in the number of SRS genes in different Cucurbitaceae crops implied likely gene loss or duplication events during evolution. Analysis of promoter cis-regulatory elements indicated that these SRS genes may be involved in hormone response, growth and development, and biotic and abiotic stress responses in plants. Most of the CmSRS genes in melons were expressed in the roots, with a few expressed in the leaves and ovaries. In addition, CmSRS expression was induced by biotic (wilt and powdery mildew) and abiotic (drought and salt) stresses. Subcellular localization of CmSRS proteins showed predominant expression in the nucleus. CONCLUSIONS: A total of 60 Cucurbitaceae SRS genes are present in the genomes of seven Cucurbitaceae crops. These cucurbit SRS genes seem to have maintained similar characteristics and functions during the evolutionary process. These results lay the foundation for the study of biological functions of SRS genes in Cucurbitaceae crops.