Rice heterotrimeric G-protein gamma subunits (RGG1 and RGG2) are differentially regulated under abiotic stress

Abstract

Abbreviations: ABA, abscisic acid; Gc, G-protein c subunits; GPCR, G-protein coupled receptor; RGG(I), c subunit of Indica rice;ZmG, c subunit of maize; GmG, c subunit of soybean; SbG, c subunit of Sorghum; HvG, c subunit of barley; AGG, c subunit of ArabidopsisHeterotrimeric G-proteins (a, b and c subunits) are primarily involved in diverse signaling processes by transducing signals from an activated transmembrane G-protein coupled receptor (GPCR) to appropriate downstream effectors within cells. The role of a and b G-protein subunits in salinity and heat stress has been reported but the regulation of c subunit of plant G-proteins in response to abiotic stress has not heretofore been described. In the present study we report the isolation of full-length cDNAs of two isoforms of Gc [RGG1(I), 282 bp and RGG2(I), 453 bp] from rice (Oryza sativa cv Indica group Swarna) and described their transcript regulation in response to abiotic stresses. Protein sequence alignment and pairwise comparison of c subunits of Indica rice [RGG(I)] with other known plant G-protein c subunits demonstrated high homology to barley (HvGs) while soybean (GmG2) and Arabidopsis (AGG1) were least related. The numbers of the exons and introns were found to be similar between RGG1(I) and RGG2(I), but their sizes were different. Analyses of promoter sequences of RGG(I) confirmed the presence of stress-related cis-regulatory signature motifs suggesting their active and possible independent roles in abiotic stress signaling. The transcript levels of RGG1(I) and RGG2(I) were upregulated following NaCl, cold, heat and ABA treatments. However, in drought stress only RGG1(I) was upregulated. Strong support by transcript profiling suggests that c subunits play a critical role via cross talk in signaling pathways. These findings provide first direct evidence for roles of Gc subunits of rice G-proteins in regulation of abiotic stresses. These findings suggest the possible exploitation of c subunits of G-protein machinery for promoting stress tolerance in plants.

The role of G-proteins in plant immunity

“…The higher plant Arabidopsis has only one canonical G-protein α-subunit (Gα), one β-subunit (Gβ), and three γ-subunits (Gγ) 26 . However, only two Gγ were found in monocot rice species 27 . Similarly, based on N. benthamiana sequence information, it contains a single candidate Gα gene and possibly two Gβ-subunit genes.…”

Effect of air desiccation and salt stress factors on in vitro regeneration of rice (Oryza sativaL.)

“…[2][3][4][5] Drought and salinity are the major abiotic stresses that adversely affect the overall metabolic activities and cause plant demise. 6,7 Certain crops reduced their production capabilities in high saline conditions. 8 Over 2 million acres of agricultural land has been estimated which lost from production per every year due to occurrence of high Na C and Cl ¡ ions in soil.…”

Small and Large G Proteins in Biotic and Abiotic Stress Responses in Plants

“…However, in drought stress, only RGG1 is upregulated. Promoter analysis of RGG1 and RGG2 revealed presence of stressrelated cis -regulatory signature motifs, supporting their role in abiotic stress response (Yadav et al 2012 ;Yadav et al 2013 ). Similar study involving in silico characterization of cis -regulatory elements of RGB1 , encoding the Gβs of Indica rice, revealed the presence of stress-related cis -regulatory elements.…”