ci21A/Asr1 expression influences glucose accumulation in potato tubers

Abstract

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.

The ZmASR1 Protein Influences Branched-Chain Amino Acid Biosynthesis and Maintains Kernel Yield in Maize under Water-Limited Conditions

“…Maximum likelihood and Bayesian reconstruction methods were congruent and confirmed the previously established division of plant ASR proteins into three distinct clades corresponding to conifer, eudicot, and monocot sequences (Supplemental Fig. S1; Frankel et al, 2007). By adding all available maize sequences, we showed that within monocots, the Commelinid sequences form a monophyletic group, with Poaceae sequences falling into two distinct clades, the I-1/I-2/I-3 clade and the II-1/ II-2 clade (Supplemental Fig.…”

“…ASR overexpression studies in plants are exemplified by works carried out on Solanoideae (Kalifa et al, 2004b;Frankel et al, 2007) and Arabidopsis, although the latter does not include any ASR homologous genes (Yang et al, 2005;Liu et al, 2010). Our study demonstrated that ZmASR1-OE improved the kernel yield of transgenic maize in the field under well-watered and water-limited conditions.…”

“…Moreover, ABA induces some ASR genes in a range of plant species, including tomato, tobacco, grape, banana, sugarcane (Saccharum officinarum), and rice (Rossi et al, 1998;Sugiharto et al, 2002;Cakir et al, 2003;Takasaki et al, 2008;Henry et al, 2011). Sugars such as Glc also exhibit interactions with ABA in controlling seedling development (Rolland et al, 2006), and grape and tomato ASR proteins may be involved in Glc metabolism (Cakir et al, 2003;Frankel et al, 2007). Additionally, polyethylene glycol (PEG)-induced water stress increases tomato, potato (Solanum tuberosum), and sugarcane ASR transcript levels (Amitai-Zeigerson et al, 1995;Huang et al, 2000;Doczi et al, 2002;Sugiharto et al, 2002).…”

“…Since their discovery more than a decade ago, they have been described as accumulating to high levels during plant developmental processes, such as fruit ripening, pollen maturation, and Glc metabolism (Iusem et al, 1993;Wang et al, 1998;Cakir et al, 2003;Frankel et al, 2007;Yang et al, 2008), and in response to diverse stresses, including water deficit, salt, cold, limited light, and, lately, pathogen attack (Schneider et al, 1997;Riccardi et al, 1998;Vaidyanathan et al, 1999;Huang et al, 2000;Maskin et al, 2001;Kalifa et al, 2004b;Liu et al, 2010;Philippe et al, 2010;Henry et al, 2011). Nevertheless, it is noteworthy that their exact function remains enigmatic.…”

“…SlASR1 and the grape (Vitis vinifera) ASR protein, VvMSA (for maturation-, stress-, and abscisic acid-induced protein), have been shown to possess DNA-binding activity (Cakir et al, 2003;Kalifa et al, 2004a;Rom et al, 2006;Maskin et al, 2007;Shkolnik and Bar-Zvi, 2008). On the basis of such findings, these ASR proteins have been proposed to regulate the transcription of sugarand abiotic stress-regulated genes in fruit and vegetative tissues, respectively (Cakir et al, 2003;Kalifa et al, 2004b;Frankel et al, 2007;Saumonneau et al, 2008). However, a dual function of LLA23 and SlASR1 proteins as a regulator and a protective molecule upon water deficit has also been proposed (Yang et al, 2005Konrad and Bar-Zvi, 2008).…”