ci21A/Asr1 expression influences glucose accumulation in potato tubers
- 247 Downloads
Asr genes are exclusively found in the genomes of higher plants. In many species, this gene family is expressed under abiotic stress conditions and during fruit ripening. The encoded proteins have nuclear localisation and consequently a transcription factor function has been suggested. Interestingly, yeast-one-hybrid experiments revealed that a grape ASR binds to the promoter of a hexose transporter gene (VvHT1). However, the role of these proteins in planta is still elusive. By using a reverse genetics approach in potato we found that modification of Asr1 expression has no incidence on the aerial phenotype of the plant but exerts a dramatic effect in tuber. Asr1 antisense potatoes displayed decreased tuber fresh weight whereas Asr1 overexpressors had a diminished number of tubers. Moreover, overexpression lines showed lower transcript levels of a plasma membrane hexose transporter and a concomitant decrease in glucose content in parenchyma cells of potato tubers. On the same hand glucose uptake rate was also reduced in one of the overexpressing lines. It thus seems likely that Asr1 is involved in the control of hexose uptake in heterotrophic organs. In addition, the transgenic plants were characterized by several other changes in steady state metabolite levels. Results presented here support a role for ci21A/Asr1 in glucose metabolism of potato tuber.
KeywordsTomato Asr genes Hexose metabolism Potato tuber
We are grateful to Prof. Lothar Willmitzer for support and helpful discussion. We acknowledge the excellent care of greenhouse plants to Helga Kulka. We acknowledge financial support from Max Planck Society (ARF, AN, and FC), DAAD (NF and DC), EMBO (NF and FC), University of Buenos Aires (NDI), CONICET (NF, FC and NDI) and INTA (FC).
- Carrari F, Baxter C, Usadel B, Urbanczyk-Wochniak E, Zanor MI, Nunes-Nesi A, Nikiforova V, Centero D, Ratzka A, Pauly M, Sweetlove L, Fernie AR. (2006) Integrated analysis of metabolite and transcript levels reveals the metabolic shifts that underlie tomato fruit development and highlight regulatory aspects of metabolic network behavior. Plant Physiol 142:1380–1396PubMedCrossRefGoogle Scholar
- Fernie AR, Riesmeier JW, Martiny A, Ramalingam S, Willmitzer L, Trethewey RN (2000) Consequences of the expression of a bacterial glucokinase in potato tubers, both in combination with and independently of a yeast-derived invertase. Aus J Plant Physiol 27:827–833Google Scholar
- Muschak M, Hoffmann-Benning S, Fuss H, Kossmann J, Willmitzer L, Fisahn J (1997) Gas exchange and ultrastructural analysis of transgenic potato plants expressing mRNA antisense construct targeted to the cp-fructose-1.6-bisphosphate phosphatase. Photosynthetica 33:455–465Google Scholar
- Patrick JW, Offler CE (1996) Post-sieve element transport of photoassimilates in sink regions. J Exp Bot 47:1167–1177Google Scholar
- Sambrook J, Fritsch EF, Maniatis T (1989) Molecular cloning: a laboratory manual, 2nd edn. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NYGoogle Scholar
- Strand A, Zrenner R, Trevanion S, Stitt M, Gustafsson P, Gardestrom P (2000) Decreased expression of two key enzymes in the sucrose biosynthesis pathway, cytosolic fructose-1,6-bisphosphatase and sucrose phosphate synthase, has remarkably different consequences for photosynthetic carbon metabolism in transgenic Arabidopsis thaliana. Plant J 23:759–770PubMedCrossRefGoogle Scholar
- Tauberger E, Fernie AR, Emmermann M, Renz A, Kossmann J, Willmitzer L, Trethewey RN (2000). Antisense inhibition of plastidial phosphoglucomutase provides compelling evidence that potato tuber amyloplasts import carbon from the cytosol in the form of glucose-6-phosphate. Plant J 23:43–53PubMedCrossRefGoogle Scholar