Genome-Wide Identification, Evolutionary Analysis and Expression Profiles of LATERAL ORGAN BOUNDARIES DOMAIN Gene Family in Lotus japonicus and Medicago truncatula.

Tianquan Yang,Hua He,Genwang Yue Fang,Jianghua Chen,Meng-Xiang Sun

doi:10.1371/journal.pone.0161901

Abstract

The LATERAL ORGAN BOUNDARIES DOMAIN (LBD) gene family has been well-studied in Arabidopsis and play crucial roles in the diverse growth and development processes including establishment and maintenance of boundary of developmental lateral organs. In this study we identified and characterized 38 LBD genes in Lotus japonicus (LjLBD) and 57 LBD genes in Medicago truncatula (MtLBD), both of which are model legume plants that have some specific development features absent in Arabidopsis. The phylogenetic relationships, their locations in the genome, genes structure and conserved motifs were examined. The results revealed that all LjLBD and MtLBD genes could be distinctly divided into two classes: Class I and II. The evolutionary analysis showed that Type I functional divergence with some significantly site-specific shifts may be the main force for the divergence between Class I and Class II. In addition, the expression patterns of LjLBD genes uncovered the diverse functions in plant development. Interestingly, we found that two LjLBD proteins that were highly expressed during compound leaf and pulvinus development, can interact via yeast two-hybrid assays. Taken together, our findings provide an evolutionary and genetic foundation in further understanding the molecular basis of LBD gene family in general, specifically in L. japonicus and M. truncatula.

Highlights

LATERAL ORGAN BOUNDARIES DOMAIN (LBD) proteins, a plant-specific transcription factor family, possess a characteristic N-terminal LOB domain and play important roles in many aspects of plant development
The LBD gene family has been extensively studied in diverse species [1,16,17,18] but very little is known in legumes
We identified 38 and 57 putative LBD transcription factors in L. japonicus and M. truncatula respectively, both of which are important model plants in legumes

Summary

Introduction

LATERAL ORGAN BOUNDARIES DOMAIN (LBD) proteins, a plant-specific transcription factor family, possess a characteristic N-terminal LOB domain and play important roles in many aspects of plant development. The LBD protein typically contains four highly conserved cysteine (C) residues in a CX2CX6CX3C zinc finger-like motif ( called C block, where X represents variable residues) that is suggested to play crucial role in DNA binding. Two other conserved features are found in the N-terminal half of the LBD: an invariant glycine residue and a leucine-zipper-like sequence LX6LX3LX6L [1,2]. LBD Gene Family in Legume can be divided into two classes (class I and II) based on conserved motif number and structural features. LBD proteins function in the nucleus and bind to the conserved nucleotide consensus sequence GCGGCG. There is evidence that the interaction between LBD and bHLH proteins can reduce the DNA-binding affinity of LBDs [3]

Methods

Results

Conclusion