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

Bhuwaneshwar S Mishra,Muhammed Jamsheer K,Dhriti Singh,Ashverya Laxmi,Manvi Sharma

doi:10.3389/fpls.2017.01812

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.

Highlights

In seed crops like rice, the grain size is an important agronomic trait which determines yield
In both P. abies and A. trichopoda, BLAST. Search identified another protein which has similarity with the BG proteins in the middle and C-terminal regions (Figure 1, Supplementary Figure S1). We named these proteins as BIG GRAIN LIKE (BGL)
Consistent with the sequence divergence observed among BG and BGL proteins, in the Bayesian phylogenetic interference of A. trichopoda and P. abies BG and BGL proteins, they recovered to distinct clades (Supplementary Figure S2)

Summary

Introduction

In seed crops like rice, the grain size is an important agronomic trait which determines yield. Studies identified many important determinants of grain size in rice which has the potential to be used for crop manipulation (Zuo and Li, 2014). The BIG GRAIN 1 (OsaBG1) has been recently identified as a positive regulator of grain size in rice. The constitutive expression of OsaBG1 in Arabidopsis thaliana resulted in an increase in seed size (Liu et al, 2015). Apart from increase in seed size, enhanced expression of BG1 in rice and A. thaliana resulted in an increase in biomass suggesting that this gene is a general promoter of growth (Liu et al, 2015). OsaBG1 is a primary auxin response gene and increased expression resulted in enhanced

Methods

Results

Conclusion