Altered carbohydrate metabolism in the storage roots of sweetpotato plants overexpressing the SRF1 gene, which encodes a Dof zinc finger transcription factor

Abstract

In order to characterize the functions of the sweetpotato SRF1 gene, which encodes a Dof zinc finger transcriptional factor preferentially expressed in the storage roots, we isolated its full length cDNA and produced transgenic sweetpotato plants with altered SRF1 expression levels. The isolated cDNA of SRF1 encoded a polypeptide of 497 amino acids and was closely related to the cyclic Dof factors of Arabidopsis and the ascorbate oxidase binding protein of pumpkin. SRF1 was most highly expressed in storage roots, although some expression was also observed in other vegetative tissue. Transgenic plants overexpressing SRF1 showed significantly higher storage root dry matter content compared to the original cultivar Kokei No. 14 or control transgenic plants. In these plants, the starch content per fresh weight of the storage roots was also higher than that of the wild-type plants, while the glucose and fructose content drastically decreased. Among the enzymes involved in the sugar metabolism, soluble acid invertase showed a decreased activity in the transgenic plants. Gene expression analysis showed that the expression of Ibbetafruct2, which encodes an isoform of vacuolar invertase, was suppressed in the transgenic plants overexpressing the SRF1 gene. These data suggest that SRF1 modulates the carbohydrate metabolism in the storage roots through negative regulation of a vacuolar invertase gene.

Genome-wide analysis and expression profiling of DNA-binding with one zinc finger (Dof) transcription factor family in potato

“…Dof genes are reported to be involved in a wide range of plant biological processes, such as seed germination (Papi et al, 2000;Gualberti et al, 2002;Boccaccini et al, 2014), accumulation of storage proteins (Vicente-Carbajosa et al, 1997;Yamamoto et al, 2006;Dong et al, 2007) and lipids (Wang et al, 2007) in developing seeds, regulation of genes involved in plant nitrogen assimilation Rueda-L opez et al, 2008;Kurai et al, 2011;Santos et al, 2012), and carbon fixation (Yanagisawa, 2000;Tanaka et al, 2009;Kurai et al, 2011). Dof TFs also play important roles in the regulation of secondary metabolic processes, such as biosynthesis of glucosinolates and flavonoids (Skirycz et al, 2006(Skirycz et al, , 2007, and cell cycle regulation (Skirycz et al, 2008).…”

Transcription Regulation of Abiotic Stress Responses in Rice: A Combined Action of Transcription Factors and Epigenetic Mechanisms

“…Zn finger TFs have been implicated in distinct pathways, such as nutrient homeostasis and root development (Devaiah et al, 2007), flower development , carbohydrate metabolism (Tanaka et al, 2009) and light and hormonal signaling (Feurtado et al, 2011).…”

Storage products and transcriptional analysis of the endosperm of cultivated wheat and two wild wheat species

“…A more global overview of the starch and carbohydrate biosynthetic pathway may reveal greater sequence and gene expression differences caused by domestication. Several aspects of starch transcriptional regulation are poorly understood and perhaps under-studied and thus more effort is needed in this area (Sun et al 2005;Tanaka et al 2009). …”