Heterotrimeric G-protein α subunit (RGA1) regulates tiller development, yield, cell wall, nitrogen response and biotic stress in rice

Abstract

G-proteins are implicated in plant productivity, but their genome-wide roles in regulating agronomically important traits remain uncharacterized. Transcriptomic analyses of rice G-protein alpha subunit mutant (rga1) revealed 2270 differentially expressed genes (DEGs) including those involved in C/N and lipid metabolism, cell wall, hormones and stress. Many DEGs were associated with root, leaf, culm, inflorescence, panicle, grain yield and heading date. The mutant performed better in total weight of filled grains, ratio of filled to unfilled grains and tillers per plant. Protein–protein interaction (PPI) network analysis using experimentally validated interactors revealed many RGA1-responsive genes involved in tiller development. qPCR validated the differential expression of genes involved in strigolactone-mediated tiller formation and grain development. Further, the mutant growth and biomass were unaffected by submergence indicating its role in submergence response. Transcription factor network analysis revealed the importance of RGA1 in nitrogen signaling with DEGs such as Nin-like, WRKY, NAC, bHLH families, nitrite reductase, glutamine synthetase, OsCIPK23 and urea transporter. Sub-clustering of DEGs-associated PPI network revealed that RGA1 regulates metabolism, stress and gene regulation among others. Predicted rice G-protein networks mapped DEGs and revealed potential effectors. Thus, this study expands the roles of RGA1 to agronomically important traits and reveals their underlying processes.

Comparative Transcriptomic Analyses of Nitrate-Response in Rice Genotypes With Contrasting Nitrogen Use Efficiency Reveals Common and Genotype-Specific Processes, Molecular Targets and Nitrogen Use Efficiency-Candidates

“…This is evidenced by genome sequences of 3000 rice genotypes ( Li et al, 2014 ) and growing functional genomics of N ( Li et al, 2018 ; Pathak et al, 2020 ; Mandal et al, 2022 ). Further, the recent NUE phenotype ( Sharma et al, 2018 , 2021 ; Pathak et al, 2021 ) growing quantitative trait loci (QTL) and genotyping ( Kumari et al, 2021 ) make rice an ideal target crop for NUE improvement. A recent simulation showed that $743 million per year could be saved by a 20% increase in rice NUE ( Langholtz et al, 2021 ), while the global expenditure in that direction is not even a tiny fraction of it.…”

Heterotrimeric G protein α subunit (GPA1) regulates the response to low-nitrogen stress in Arabidopsis by interacting with AtNRT1.4 and AtATG8a

“…Some studies have demonstrated that G protein plays a vital role in regulating low-nitrogen stress in plants (Sun et al, 2014; Liang et al, 2018; Kaur et al, 2018; Pathak et al, 2021). However, the potential regulatory mechanism remains largely unknown.…”

“…In general, following receptor-mediated activation, the heterotrimeric G protein transmits external signals to cells via various downstream cytosolic effectors to regulate biological processes (Bommert et al, 2013; Urano et al, 2015; Lee et al, 2017; Roy et al, 2019). AtGPA1 phosphorylates ABA-insensitive 1 ( ABI1 ) and phospholipase Dα1 ( PLDα1 ) to regulate ABA-dependent stomatal opening and closure in Arabidopsis (Roy et al, 2016; Hei et al, 2018; Pathak et al, 2021). The heterotrimeric G protein also interacts with plant-specific receptor-like kinases (RLKs) and receptor-like proteins (RLPs) to regulate multiple immune responses, shoot apical meristem development, and nodule formation (Bommert et al, 2013; Aranda et al, 2015; Pandey, 2020).…”

“…In Arabidopsis , heterotrimeric G proteins consist of one canonical α subunit (GPA1), one β subunit (AGB1), and at least three γ subunits (AGG), all of which play crucial roles in almost all aspects of growth and development (Pathak et al, 2021). During biotic and abiotic stress, these proteins also control key agronomic traits, including crop yield (Pandey, 2019).…”

“…Further evidence has indicated that DEP1 can interact with other two G protein subunits, RGA1 (G protein α subunit) and RGB1 (G protein β subunit), to regulate NUE and yield in rice (Huang et al, 2014). Increasing evidence has revealed that RGA1 also regulates the nitrogen-signaling pathway through other genes, such the bHLH gene family members, nitrite reductase, OsCIPK23 , and urea transporters in rice (Pathak et al, 2021). Setaria plants overexpressing AGG3 (rice homologs of the Arabidopsis group III Gγ subunit) exhibit better growth during early development under conditions of low nitrogen (Kaur et al, 2018).…”