Abstract:
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Objective】This study aimed to perform identification, subcellular localization, and expression analysis of the longan FLOE gene family members, explore the mechanism underlying the FLOE gene family during longan somatic embryogenesis and stress response, providing theoretical reference for molecular breeding of stress-tolerant longan.【
Method】Using the
Arabidopsis thaliana FLOE family protein sequences as reference sequences, DlFLOE gene family members were identified from longan genome. Bioinformatic methods were employed to analyze their sequence characteri-stics. Real-time fluorescence quantitative PCR was utilized to analyze different early stages of somatic embryogenesis and expression patterns under hormones and abiotic stresses of DlFLOE gene family.【
Result】Three DlFLOE gene family members were identified and named
DlFLOE1,
DlFLOE2, and
DlFLOE3 according to their positions on chromosomes. The number of amino acids encoded by DlFLOE family members ranged from 440 to 559, with relative molecular mass ranged from 48.36 to 61.25 kD, and theoretical isoelectric points of 5.51-6.16, indicating that they were all hydrophilic and unstable proteins. The DlFLOE2 protein located in the vacuole, while DlFLOE1 and DlFLOE3 proteins were located in nucleus. Phylogenetic analysis results showed that the
DlFLOE3 gene clustered with the LITCHI022451.m1 gene of
Litchi chinensis, indicating that the homologous genes of Sapindaceae were conserved. According to results of gene and protein structure analysis as well as collinearity analysis, the
DlFLOE2 gene had five intron, and the rest genes contained two introns, with intron length showing difference between species; most members contained DUF1421 domain; a colli-near relationship was found between
DlFLOE2 and
DlFLOE3 genes, with the two genes located on different chromosomes and the
Ka/
Ks=0.261, suggesting that they had been under purifying selection during evolution. Promoter cis-element analysis and subcellular localization results showed that the promoters of DlFLOE family members contained elements responsive to light and drought stress; the
DlFLOE1 gene had a strong positive response to high-concentration PEG and was located in nucleus, which was consistent with predictions from online software. Real-time fluorescence quantitative PCR detection results indicated that DlFLOE genes family members responded to different hormones and abiotic stress treatments, but their expression patterns varied.【
Conclusion】The three FLOE gene family members identified from the longan genome exhibit functional differentiation and clear spatiotemporal specificity, showing important roles in stress response and hormone regulation for longan. The
DlFLOE1 gene shows a strong positive response to high-concentration PEG, thus, it is suggested to be involved in drought-responsive pathways.