Expression of the Arabidopsis high‐affinity hexose transporter STP13 correlates with programmed cell death

Abstract

We report the biochemical characterization in Xenopus oocytes of the Arabidopsis thaliana membrane protein, STP13, as a high affinity, hexose-specific H + -symporter. Studies with kinase activators suggest that it is negatively regulated by phosphorylation. STP13 promoter GFP reporter lines show GFP expression only in the vascular tissue in emerging petals under non-stressed conditions. Quantitative PCR and the pSTP13-GFP plants show induction of STP13 in programmed cell death (PCD) obtained by treatments with the fungal toxin fumonisin B1 and the pathogen Pseudomonas syringae. A role for STP13 in PCD is supported by microarray data from e.g. plants undergoing senescence and a strong correlation between STP13 transcripts and the PCD phenotype in different accelerated cell death (acd11) mutants.

Monosaccharide Absorption Activity of Arabidopsis Roots Depends on Expression Profiles of Transporter Genes under High Salinity Conditions

“…These results were in accordance with the results of the complementation assay (Fig. 2B) and from previous reports (10,25,26). Furthermore, the substrate specificities of STP1 and STP4 in yeast cells were in agreement with the results of the competition assay in Arabidopsis roots shown in Fig.…”

“…This suggests that the role of STP13 might be more important under high salinity than under normal conditions. Our current data and those from previous reports have demonstrated that STP13 has broader substrate specificity than the other STP family transporters (26). Various types of monosaccharides might leak from roots when the cell membrane is broken under conditions of high salinity, and STP13 may reabsorb these monosaccharides more efficiently than other transporters.…”

“…STP13 is the only STP transporter that has been described as an abiotic stress-inducible gene (26). The increase in monosaccharide uptake under high salinity was dependent on the induction of STP13 because this increase was not detected for stp1-1 stp13-1.…”

Involvement of Abscisic Acid in the Coordinated Regulation of a Stress-Inducible Hexose Transporter (VvHT5) and a Cell Wall Invertase in Grapevine in Response to Biotrophic Fungal Infection

“…Uptake studies with VvHT1 and VvHT5 reveal that while there is little difference in their affinity for Glc, VvHT5 is capable of binding Fru whereas VvHT1 is not (Vignault et al, 2005;Hayes et al, 2007). Interestingly, VvHT5 is most closely related to the Arabidopsis HT AtSTP13 (83% amino acid identity compared with only 48%-58% identity for the other 13 AtSTPs), which has also been demonstrated to facilitate Fru uptake into Xenopus oocytes (Norholm et al, 2006). The ability to transport Fru is not a feature commonly demonstrated by monosaccharide transporters (Schofield et al, 2009), and as such, VvHT5 would have the capacity to provide more invertase-generated hexose to stressed cells than other VvHT proteins.…”

The role of sugar signaling in plant defense responses against fungal pathogens

“…VvHT5 shows the highest similarity to AtSTP13 and both of them have a comparable high affinity to glucose (K m = 89 lM and K m = 74 lM, respectively) (Norholm et al 2006;Hayes et al 2007;Afoufa-Bastien et al 2010). Furthermore, the expression of these two transporters is described to be induced in response to pathogen attack (Norholm et al 2006;Hayes et al 2010). Induction of STP sugar transporters is a characteristic feature of plant response to various stresses, both biotic and abiotic.…”