Identification of LEAFY gene in longan involved in flower induction

Abstract

Abstract Backgroud: Flowering at the right time is a very important factor affecting the stable annual yield of longan. However, a lack of knowledge of the regulatory mechanism and key genes of longan flowering restricts the healthy development of the longan industry. Therefore, identifying the relevant genes and analyzing their regulatory mechanism are essential for scientific research and the development of the longan industry. Here, we isolated a LEAFY homologue gene from longan, DlLFY, and identified its function. Results: DlLFY contains a 1167 bp open reading frame and encodes 388 amino acids. The amino acid sequence has a typical LFY/FLO family domain. DlLFY was expressed in all the tested tissues, expect for leaf, pericarp, and ulp, with the highest expression occurring in flower buds. The expression of DlLFY was significant upregulated at the early flower induction stage in “SX” (“Shixia”). The results of subcellular localization and transactivation analysis show that DlLFY is a kind of typical transcript factor with transcriptional activator. Moreover, overexpression of DlLFY in Arabidopsis promoted early flowering and restrained growth, resulting in reduced plant height and number and area of rosette leaves of transgenic plants. DNA affinity purification sequencing (DAP-Seq) analysis showed that 13 flower-related genes corresponding to five homologous genes of Arabidopsis may be the binding sites and putative target genes. Among these five flower-related genes, only AtTFL1 was strongly inhibited in transgenic lines. Conclusion: Taken together, these results indicate that DlLFY plays a pivotal role in controlling longan flowering, possibly by negatively regulating TFL1.