Genome-Wide Identification and Expression, Protein–Protein Interaction and Evolutionary Analysis of the Seed Plant-Specific BIG GRAIN and BIG GRAIN LIKE Gene Family

Abstract

BIG GRAIN1 (BG1) is an auxin-regulated gene which functions in auxin pathway and positively regulates biomass, grain size and yield in rice. However, the evolutionary origin and divergence of these genes are still unknown. In this study, we found that BG genes are probably originated in seed plants. We also identified that seed plants evolved a class of BIG GRAIN LIKE (BGL) genes which share conserved middle and C-terminal motifs with BG. The BG genes were present in all monocot and eudicot species analyzed; however, the BGL genes were absent in few monocot lineages. Both BG and BGL were found to be serine-rich proteins; however, differences in expansion and rates of retention after whole genome duplication events were observed. Promoters of BG and BGL genes were found to be enriched with auxin-responsive elements and the Arabidopsis thaliana BG and BGL genes were found to be auxin-regulated. The auxin-induced expression of AthBG2 was found to be dependent on the conserved ARF17/19 module. Protein-protein interaction analysis identified that AthBG2 interact with regulators of splicing, transcription and chromatin remodeling. Taken together, this study provides interesting insights about BG and BGL genes and incentivizes future work in this gene family which has the potential to be used for crop manipulation.

Genetic control of tracheid properties in Norway spruce wood

“…OsaBG1 encodes a membrane protein regulating auxin transport and sensitivity, and positively affecting plant biomass and seed size. The gene belongs to a small family containing nine members in spruce 86 . Auxin has long been known to act as a key hormone essential for the induction of vascular strands, cambial growth and secondary wall deposition [88][89][90][91] .…”

Translating auxin responses into ovules, seeds and yield: Insight from Arabidopsis and the cereals

“…In addition, Liu et al () isolated a dominant mutant, big grain1‐D ( Bg1‐D ), that produces extra‐large grains caused by overexpression of the BG1 gene. BG1 encodes a novel membrane‐localized protein and may physically interact with auxin transporters (Liu et al ; Mishra et al ), and Bg1‐D mutants exhibit increased basipetal auxin transport and altered auxin distribution, suggesting a role in regulating auxin transport.…”

Maize BIG GRAIN1 homolog overexpression increases maize grain yield

“…Public and proprietary maize genomes and transcriptomes were extensively searched for gene family members related to rice OS-BG1 (BIG GRAIN1) gene (Locus OS03g0175800). Mishra et al (2017) identified 10 candidate maize family members. We determined that there are 8 members of the maize BG1-related gene family with over 20% amino acid identity (AAID) to OS-BG1 (Table S1).…”

“…Promoter analyses among native ZM-BG1H1 homologs OS-BG1 and BG1 homolog promoters were reported to possess auxin response-related motifs (Mishra et al, 2017). We initiated a de novo search for conserved motifs found in the proximal promoter, the first 1000 nts upstream from the ATG, for each of BG1 homologs across 5 species: ZM-BG1H1, the OS-BG1 and BG1 homologs from Sorghum, Brachypodium and Setaria ( Figure S7).…”

“…The OS‐BG1 belongs to a larger gene family that is vascular plant specific and has undergone extensive diversification. This family possesses uncharacterized conserved domains, and it includes at least one nuclear‐targeted family member (Mishra et al , 2017), suggesting diverse molecular functions.…”