Genome-Wide Identification and Expression Analysis of FAR1/FHY3 Gene Family in Cucumber (Cucumis sativus L.)

The FAR1-RELATED SEQUENCE1 (FAR1) and FAR-RED ELONGATED HYPOCOTYL3 (FHY3) gene family plays a crucial role in various physiological and developmental processes, including seed germination, photomorphogenesis, flowering and stress responses. However, genome analysis of FAR1/FHY3 in cucumber (Cucumis sativus L.) has not been systemically investigated. In this study, 20 FAR1/FHY3 genes in cucumber were identified. The 20 FAR1/FHY3 members are randomly distributed on six chromosomes. The examination of subcellular localization indicated that the nucleus is the primary site where the 20 FAR1/FHY3 members are predominantly found. The analysis of the phylogenetic tree further revealed that the FAR1/FHY3 genes in cucumber are grouped into three distinct categories, exhibiting remarkable resemblance to the corresponding genes in other plant species. The analysis of cis-acting elements showed that most FAR1/FHY3 genes contain a variety of hormones as well as stress-related and light response elements. Through scrutinizing the expression patterns in various tissues, it was discerned that these genes are prominently expressed in roots, stems and leaves, with roots exhibiting the highest level of expression. Additionally, the 20 cucumber FAR1/FHY3 genes are all responsive to jasmonic acid methyl ester (Me-JA) and abscisic acid (ABA). CsFAR6 and CsFAR12 are significantly induced by Me-JA and ABA, respectively. CsFAR13 positively responds to NaCl and PEG6000 stresses. CsFAR11, CsFAR15 and CsFAR13 are significantly induced by the dark. The findings presented in this study establish compelling support for the potential involvement of FAR1/FHY3 genes in the growth, development and stress response of cucumbers. Moreover, these results serve as a solid basis for future investigations into the functional analysis of FAR1/FHY3.