A WRKY transcription factor participates in dehydration tolerance in Boea hygrometrica by binding to the W-box elements of the galactinol synthase (BhGolS1) promoter

Abstract

Accumulation of compatible osmolytes, such as soluble sugars, in plants is an important osmoprotective mechanism. Sugars play a role in osmotic adjustment and are associated with stabilization of proteins and cell structures, reactive oxygen species scavenging, signaling functions or induction of adaptive pathways. Galactinol is the galactosyl donor for the synthesis of raffinose family oligosaccharides (RFOs) and its synthesis by galactinol synthase (GolS) is the first committed step of the RFOs biosynthetic pathway. GolS genes are induced by a variety of stresses in both stress-sensitive and tolerant-plant species; however, the mechanism of transcriptional regulation is not fully established. In this paper, we characterized a GolS gene (BhGolS1) that was dehydration and ABA-inducible in the resurrection plant Boea hygrometrica and conferred dehydration tolerance in a transgenic tobacco system. Four W-box cis-elements were identified in the BhGolS1 promoter and shown to be bound by an early dehydration and ABA-inducible WRKY gene (BhWRKY1). These data suggest a mechanism where BhWRKY1 is likely to function in an ABA-dependent signal pathway to regulate BhGolS1 expression, which leads to the accumulation of RFOs in desiccation-tolerant B. hygrometrica leaves.

Genetic Analysis of Desiccation Tolerance inSaccharomyces cerevisiae

“…Intriguingly, while the Med2p submodule activates hundreds of genes, it has been implicated in specifically regulating other stress responses including the response to iron deficiency and the general stress response pathway controlled by Msn2p/ Msn4p (Van De Peppel et al 2005). Transcriptional regulation of water homeostasis has precedent as drought tolerance in plants is also transcriptionally regulated (Moore et al 2009;Wang et al 2009). Finally, Med2p cannot be the only positive regulator of desiccation effectors, since desiccation tolerance can occur independent of Med2p function in saturated cultures of both wild-type and ras2Δ r 2 cells (this study).…”

The Solanum commersonii Genome Sequence Provides Insights into Adaptation to Stress Conditions and Genome Evolution of Wild Potato Relatives

“…Among the latter, we found a significant upregulation of S. commersonii galactinol synthase (GOLS1) under both NAC and AC conditions. Previously, overexpression of GOLS1 from Medicago falcata or Boea hygrometrica promoted the biosynthesis of increased amounts of raffinose family oligosaccharides, such as galactinol, raffinose, and stachyose, and resulted in elevated tolerance to low temperatures in transgenic tobacco (Nicotiana tabacum) plants (Wang et al, 2009;Zhuo et al, 2013). Given that, we hypothesize that high expression of S. commersonii GOLS1 in conjunction with the increased activity of the aforementioned cold-associated and -inducible proteins might contribute to S. commersonii frost tolerance.…”

Plant Desiccation Tolerance and its Regulation in the Foliage of Resurrection “Flowering-Plant” Species

“…In the foliage of the resurrection gesneriad, Boea hygrometrica (Bunge) R.Br., BhWRKY1, induced by drought stress and by ABA, binds to the promoter of the galactinol synthase gene BhGolS1 [63]. Overexpression of WRKY in rice induced expression of galactinol synthase and raffinose synthase genes and also improved drought tolerance [62].…”