Four ClEF1A Genes Involved in Self-Incompatibility in 'Xiangshui Lemon' Confer Early Fowering and Increase Stress Tolerance in Transgenic Arabidopsis

The plant elongation factor eEF1A is involved in coregulating not only the translation of proteins and controlling translation-related signaling but also in signaling associated with cell growth, stress response and motility, controlling apoptosis and responding to adversity in plants. In this study, four eEF1A genes, namely, ClEF1A-1, ClEF1A-2, ClEF1A-3, and ClEF1A-4, were identified from the genomic and ubiquitin-modified omics data of the 'Xiangshui Lemon', and bioinformatics analysis revealed that these four genes have relatively similar structures with conserved sequences; ClEF1A-1 and ClEF1A-4 were highly expressed in pollen, and temporal expression analysis demonstrated that the expression of ClEF1As was significantly greater under self-pollination than under cross-pollination. All four genes were localized in the nucleus. ClEF1A overexpression promoted early flowering and improved drought and salt stress tolerance in transgenic Arabidopsis plants. Yeast two-hybrid assays revealed that ClEF1As interacted with F-box, eIF3-G, the organ-specific-like protein S2, AGL62, S1-RNase, S2-RNase, S3-RNase and S4-RNase. This study demonstrated the functions of ClEF1As and provided a baseline for further studies on the associations of ClEF1As with self-incompatibility and abiotic stresses.