Functional divergence of MFT paralogues in flowering promotion and organ development in Platanus acerifolia

Two MFT -like genes, PlacMFT1 and PlacMFT2 , were isolated and characterized from London plane tree ( Platanus acerifolia ). Both genes possess the conserved four-exon/three-intron structure characteristic of the PEBP family. Phylogenetic analysis placed them into two distinct clades, MFT1 and MFT2, indicating an ancient duplication event. qRT-PCR revealed that PlacMFT1 was broadly expressed in vegetative and reproductive tissues, with high transcript levels in stems, whereas PlacMFT2 exhibited strong fruit-specific expression and complementary patterns in juvenile organs. Ectopic overexpression of either gene in Arabidopsis under the 35S promoter accelerated flowering, confirming their conserved function in promoting floral transition. However, 35S:PlacMFT1 transgenic lines displayed pleiotropic developmental abnormalities, including fused flowers, malformed floral organs, elongated pedicels with shortened siliques, and curled rosette leaves, while 35S:PlacMFT2 lines showed no obvious morphological alterations. These results indicate that the two MFT paralogs have undergone subfunctionalization through spatiotemporal expression divergence, with PlacMFT1 acquiring additional roles in organ development. This study provides insights into the functional evolution of MFT genes in basal core eudicots and establishes a molecular foundation for breeding low-fruit cultivars of London plane trees.