Genome-Wide Identification of Cucumber Lhc Genes' Family and Their Expression Analysis

Light-harvesting chlorophyll a/b-binding (Lhc) proteins are integral membrane proteins that bind to pigment molecules, playing a critical role in photosynthetic processes, including light energy harvesting and transfer. To investigate the role of the Lhc gene family in cucumber (Cucumis sativus L), genome-wide identification of CsLhc gene family members and analysis of their regulatory networks were carried out using bioinformation and molecular biology research methods at Anhui Science and Technology University. The results indicated that the Lhc family consisted of 21 members, being categorized into five subfamilies: Lhca, Lhcb, CP24, CP26, and CP29. The gene structure and motifs within each subfamily are generally conserved. CsLhcs are distributed on seven chromosomes, including one pair of tandem duplicates and two pairs of segmental duplicates. Six CsLhcs exhibit eight linear relationships with seven AtLhcs, and one CsLhc shows a syntenic relationship with one OsLhc. Analysis of the cis-acting elements in CsLhc promoters revealed their potential involvement in stress responses. Transcriptome data indicated that CsLhcs are minimally expressed in male flowers and roots, but highly expressed in other organs. Analysis of stress response processes revealed that all Lhc genes participate in at least one stress response. Five Lhc genes were confirmed to appear to have expression change using qPCR analysis under high temperature and salt stress. Particularly, under downy mildew, root-knot nematode stresses, and blight stress, up-regulated Lhc genes were the most abundant ones, indicating that the Lhc family acts as a significant role in the growth and development of cucumber. These results provide valuable insights for further understanding the characteristics of the CsLhc family and analyzing the function of the Lhc family in cucumber resistance to biotic/abiotic stresses and in molecular breeding.