One of two tandem Arabidopsis genes homologous to monosaccharide transporters is senescence-associated

A gene designated SFP1, which is similar to major facilitator superfamily monosaccharide transporters, is induced during leaf senescence. Genomic sequence analysis identified a second highly similar and closely linked gene, SFP2, suggesting that SFP1 and SFP2 may have arisen through a recent duplication event. However, RNA gel-blot analyses and histochemical localization of a reporter gene activity in transgenic plants show that SFP1 and SFP2 are differentially regulated and that only SFP1 is induced during leaf senescence. The increase in SFP1 gene expression during leaf senescence is paralleled by an accumulation of monosaccharides. Possible roles for SFP1 in sugar transport during leaf senescence are discussed.