title: Differential expression and interaction specificity of the heterotrimeric G-protein family in Brassica nigra reveal their developmental- and condition-specific roles.
abstract: Heterotrimeric G-proteins, comprised of α, β and γ subunits, are important signal transducers across phyla. The G-proteins are well characterized in the model plants Arabidopsis and rice, and their inventories are possible from a few other plant species; however, information about the roles played by G-proteins in regulating various growth and developmental traits particularly from polyploid crops is still awaited. In this study, we have isolated one Gα (BniB.Gα1), three Gβ (BniB.Gβ1-BniB.Gβ3) and four Gγ (BniB.Gγ1-BniB.Gγ4) coding sequences from the paleopolyploid Brassica nigra, a major condiment crop of the Brassicaceae family. Sequence and phylogenetic analysis revealed that whole-genome triplication events in the Brassica lineage had proportionally increased the inventory of the Gβ subunit, but not of the Gα and Gγ subunits in B. nigra. Real-time quantitative reverse transcription-PCR (qRT-PCR) analysis showed that members of the G-protein subunit genes have distinct temporal and spatial expression patterns and were differentially altered in response to various stress and phytohormone treatments, thereby suggesting differential transcriptional regulation of G-protein genes in B. nigra. Interestingly, specific members of G-protein subunits were co-expressed across plant developmental stages, and in response to different elicitor treatments. Yeast-based interaction screens further predicted that the B. nigra G-protein subunits interacted in most of the possible combinations, although showing a high degree of interaction specificity between different G-protein subunits. Our data on physical interactions coupled with the co-expression pattern of the multiple G-protein subunit genes suggested that tissue- and condition-specific functional combinations of Gαβγ heterotrimers may exist in paleopolyploid B. nigra, to control diverse growth and development processes.
authors.affiliation: National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi-110067, India.
authors.forename: Roshan
authors.initials: R
authors.lastname: Kumar
authors.affiliation: National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi-110067, India.
authors.forename: Gulab C
authors.initials: GC
authors.lastname: Arya
authors.affiliation: National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi-110067, India ncbisht@nipgr.ac.in.
authors.forename: Naveen C
authors.initials: NC
authors.lastname: Bisht
mesh_terms: D000595:Amino Acid Sequence; D018076:DNA, Complementary; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018745:Genome, Plant; D018525:Germination / Q000235:genetics; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009149:Mustard Plant / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011123:Polyploidy; D025941:Protein Interaction Mapping; D012639:Seeds / Q000235:genetics / Q000254:growth & development; D017386:Sequence Homology, Amino Acid; D013312:Stress, Physiological / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D010937:Plant Growth Regulators; D010940:Plant Proteins; D020962:Heterotrimeric GTP-Binding Proteins
keywords: Brassica nigra; Gene expression; Heterotrimeric G-proteins; Polyploidy; Protein–protein interaction; Signal transduction