Genome-wide identification of SHMT family genes in cucumber (Cucumis sativus L.) and functional analyses of CsSHMTs in response to hormones and abiotic stresses

Serine hydroxymethyltransferase (SHMT) is a pyridoxal phosphate-dependent enzyme that plays crucial roles in the photorespiration and one-carbon metabolism of plants. In the present research, we conducted a systematic analysis of the SHMT gene family in cucumber (Cucumis sativus L). Results show that a total of 6 SHMT members were identified from the cucumber genome database. CsSHMT1 and CsSHMT2 participate in a fragment duplication event, indicating that CsSHMTs may complete the expansion of family members through fragment duplication. Gene structure analysis found that the number of exons of CsSHMTs ranges from 4 to 15. Members with the same number of exons are classified into the same class in the phylogenetic analysis. Each class reflects its subcellular distribution. Expression and function analysis reveals that CsSHMTs express in a variety of plant tissues, indicating that SHMT gene expression pattern is not organ-specific. qRT-PCR analysis found that CsSHMT3 and CsSHMT5 positively respond to abscisic acid (ABA), and CsSHMT2-6 are induced by indole-3-acetic acid (IAA) and methyl jasmonate (MeJA). Abiotic stress analysis shows that CsSHMT3 is significantly induced by drought and salt stress. These results may provide useful information for further function and evolution analysis of cucumber SHMT genes.