Heterologous expression of yeast Hxt2 in Arabidopsis thaliana alters sugar uptake, carbon metabolism and gene expression leading to glucose tolerance of germinating seedlings Daniel Padilla-Chaco ´n • Elizabeth Cordoba • Teresa Olivera • Sobeida Sa ´nchez • Patricia Coello • Patricia Leo ´n • Axel Tiessen • Eleazar Martı ´nez-Barajas Received: 17 August 2009 / Accepted: 13 January 2010 / Published online: 27 January 2010 Ó Springer Science+Business Media B.V. 2010 Abstract The hexose transporter 2 gene (Hxt2) from Saccharomyces cerevisiae was expressed in Arabidopsis thaliana under control of the 35S promoter. Several inde- pendent transgenic lines were selected after confirming single gene insertion by southern blot analysis in the T4 generation. Northern blots revealed the presence of heter- ologous transcript. Radiolabeling experiments revealed an increased rate of incorporation of the non-metabolizable analog 3-O-methyl-[U-14C]-glucose. This confirmed that the yeast Hxt2 transporter was functional in Arabidopsis. No phenotypic changes at the vegetative and reproductive stages could be detected in the transgenic lines when compared to wild type plants. Shortly after germination some differences in development and glucose signaling were observed. Transgenic seedlings cultivated in liquid medium or on solid agar plates were able to grow with 3% glucose (producing bigger plants and longer roots), while development of wild type plants was delayed under those conditions. Metabolite analysis revealed that the Hxt2 transgenic lines had higher rates of sugar utilization. Transcriptional profiling showed that particular genes were significantly up- or down-regu- lated. Some transcription factors like At1g27000 were repressed, while others, such as At3g58780, were induced. The mRNA from classical sugar signaling genes such as STP1, Hxk1, and ApL3 behaved similarly in transgenic lines and wild type lines. Results suggest that the Hxt2 transgene altered some developmental processes related to the per- ception of high carbon availability after the germination stage. We conclude that the developmental arrest of wild type plants at 3% glucose not only depends on Hxk1 as the only sugar sensor but might also be influenced by the route of hexose transport across the plasma membrane. Keywords Hxt2 Á Sugar uptake Á Glucose tolerance Abbreviation Hxt2 Hexose transporter 2 Introduction Plants need to respond to environmental conditions, par- ticularly those related to the availability of mineral and organic nutrients. Some environmental inputs such as light, temperature and carbon dioxide can be sensed directly in green tissues. The integrated sum of environmental con- ditions influencing the rate of photosynthesis in source organs can also be sensed indirectly in sink organs through the amount—and type—of sugars arriving via the phloem. Biosynthetic metabolism in source tissues is linked to heterotrophic metabolism in sink tissues through the export–import and hydrolysis of sucrose. The passage of sugars involves both transport across membranes (active Electronic supplementary material The online version of this article (doi:10.1007/s11103-010-9602-y) contains supplementary material, which is available to authorized users. D. Padilla-Chaco ´n Á T. Olivera Á S. Sa ´nchez Á P. Coello Á E. Martı ´nez-Barajas (&) Facultad de Quı ´mica, Departamento de Bioquı ´mica, Universidad Nacional Auto ´noma de Me ´xico, 04510 Me ´xico D.F., Me ´xico e-mail: emtz@servidor.unam.mx E. Cordoba Á P. Leo ´n Departamento de Biologı ´a Molecular de Plantas, Universidad Nacional Auto ´noma de Me ´xico Av, Universidad 2001, Col. Chamilpa, 62250 Cuernavaca, Morelos, Me ´xico A. Tiessen Departamento de Ingenierı ´a Gene ´tica, CINVESTAV, Irapuato, Me ´xico 123 Plant Mol Biol (2010) 72:631–641 DOI 10.1007/s11103-010-9602-y