Cloning and Functional Assessments of Floral-Expressed Transporter Genes from .

Sugar transporters of the family mediate cross membrane movement of mono- and disaccharides and play vital roles in diverse physiological and pathophysiological processes, including sink-source relationship, pathogen responses, reproductive growth, and development. However, it remains to be determined how these transporters function in non-module plants of agricultural significance, given the evolutionarily diverse traits. In this study, we combined transcriptome analysis, rapid amplification of cDNA ends-cloning (RACE-cloning), expression profiling, and heterologous functional assay to identify genes that may have potential roles during flower opening and sexual reproduction in . During the anthesis, the floral organs of express seven homologous genes from all four clades of the family. and are significantly upregulated when flowers are fully opened, up to 6- and 3-fold compared to unopened buds, respectively. The other transporters, , , , and are also accumulated slightly at stage associated with fragrance release, whereas only the vacuole transporter showed small decrease in transcript level after anthesis. The , a clade II member, is capable to complement yeast cell uptake on most tested sugar substrates with a preference for hexoses, while the clade I transporter mediates merely galactose import when expressed in yeast. Our results provide first evidence for further investigation on sugar transport and allocation during flowering and reproductive processes in .