Comprehensive analyses of microtubule-associated protein MAP65 family genes in Cucurbitaceae and CsaMAP65s expression profiles in cucumber

MAP65 is a microtubule-binding protein family in plants and plays crucial roles in regulating cell growth and development, intercellular communication, and plant responses to various environmental stresses. However, MAP65s in Cucurbitaceae are still less understood. In this study, a total of 40 MAP65s were identified from six Cucurbitaceae species (Cucumis sativus L., Citrullus lanatus, Cucumis melo L., Cucurbita moschata, Lagenaria siceraria, and Benincasa hispida) and classified into five groups by phylogenetic analysis according to gene structures and conserved domains. A conserved domain (MAP65_ASE1) was found in all MAP65 proteins. In cucumber, we isolated six CsaMAP65s with different expression patterns in tissues including root, stem, leaf, female flower, male flower, and fruit. Subcellular localizations of CsaMAP65s verified that all CsaMAP65s were localized in microtubule and microfilament. Analyses of the promoter regions of CsaMAP65s have screened different cis-acting regulatory elements involved in growth and development and responses to hormone and stresses. In addition, CsaMAP65-5 in leaves was significantly upregulated by salt stress, and this promotion effect was higher in cucumber cultivars with salt tolerant than that without salt tolerant. CsaMAP65-1 in leaves was significantly upregulated by cold stress, and this promotion was higher in cold-tolerant cultivar than intolerant cultivar. With the genome-wide characterization and phylogenetic analysis of Cucurbitaceae MAP65s, and the expression profile of CsaMAP65s in cucumber, this study laid a foundation for further study on MAP65 functions in developmental processes and responses to abiotic stress in Cucurbitaceae species.