Accumulation of raffinose in rice seedlings overexpressing OsWRKY11 in relation to desiccation tolerance

Abstract

We previously reported that transgenic rice (Oryza sativa L.) lines overexpressing OsWRKY11 showed significant desiccation tolerance, as indicated by their slower water loss in detached leaves. Here we examined the contents of sucrose, glucose, fructose and raffinose. Raffinose was shown to accumulate at a significantly higher level in the transgenic plants overexpressing OsWRKY11. Microarray analysis of gene expression profile indicated that the gene expression of Os07g0209100 encoding raffinose synthase and that of Os07g0687900 encoding galactinol synthase were upregulated. These results suggest that OsWRKY11 induced activation of these genes involved in raffinose synthesis and the accumulated raffinose played an important role in the desiccation tolerance of the OsWRKY11-overexpressed plants.

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

“…Overexpression of WRKY in rice induced expression of galactinol synthase and raffinose synthase genes and also improved drought tolerance [62]. Raffinose may play a protectant role in drying resurrection plants [64].…”

“…WRKY transcription factors (TFs) bind to the W box, TTGAC(C/T), in promoters of specific genes to activate their expression [62]. The WRKY TFs occur in developing seed and are key agents in the ABA regulatory pathways that respond to environmental stresses, senescence, dormancy and germination of seeds.…”

Expression analysis of the gene family associated with raffinose accumulation in rice seedlings under cold stress

“…There have been many studies showing that the expression of genes related to biosynthesis of galactinol and raffinose is involved in several stresses, and expression specificity of the GolS genes to different stresses has also been reported in Arabidopsis. In rice, accumulation of raffinose in seedlings overexpressing OsWRKY11, which is related to heat shock and drought stress, was reported (Wu et al, 2009). It has also been reported that raffinose content in cold-tolerant rice was slightly increased by chilling treatment at 13/10 • C for 4 days (Morsy et al, 2007) and that the expression of a GolS homologous gene was induced in rice seedlings exposed to a Abbreviations: AGA, alkaline ␣-galactosidase; GolS, galactinol synthase; ORF, open reading frame; RFO, raffinose oligosaccharide; RS, raffinose synthase; SIP, seed imbibition protein.…”

Osmotic stress induces genes, enzymes and accumulation of galactinol, raffinose and stachyose in seedlings of pea (Pisum sativum L.)

“…The accumulation of galactinol and raffinose in vegetative tissues of different plant species occurs under cold, heat, drought and osmotic stresses (ElSayed et al 2014;Pastorczyk et al 2014). The concentrations of accumulated galactinol and/or raffinose can be sufficiently high to confirm the osmoprotective role of both galactosides (Sun et al 2013;Wang et al 2012a;Wu et al 2009). However, in dehydrated seedlings of wheat (Bogdan and Zagdańska 2006), winter vetch (Vicia villosa Roth) (Lahuta and Górecki 2011) and pea , the concentration of accumulated raffinose is very low.…”