Genomic Dissection and Expression Profiling Revealed Functional Divergence in Triticum aestivum Leucine Rich Repeat Receptor Like Kinases (TaLRRKs).

Shumayla Shumayla,Santosh K Upadhyay,Venugopal Mendu,Rohit Kumar,Kashmir Singh,Shailesh Sharma

doi:10.3389/fpls.2016.01374

Abstract

The leucine rich repeat receptor like kinases (LRRK) constitute the largest subfamily of receptor like kinases (RLK), which play critical roles in plant development and stress responses. Herein, we identified 531 TaLRRK genes in Triticum aestivum (bread wheat), which were distributed throughout the A, B, and D sub-genomes and chromosomes. These were clustered into 233 homologous groups, which were mostly located on either homeologous chromosomes from various sub-genomes or in proximity on the same chromosome. A total of 255 paralogous genes were predicted which depicted the role of duplication events in expansion of this gene family. Majority of TaLRRKs consisted of trans-membrane region and localized on plasma-membrane. The TaLRRKs were further categorized into eight phylogenetic groups with numerous subgroups on the basis of sequence homology. The gene and protein structure in terms of exon/intron ratio, domains, and motifs organization were found to be variably conserved across the different phylogenetic groups/subgroups, which indicated a potential divergence and neofunctionalization during evolution. High-throughput transcriptome data and quantitative real time PCR analyses in various developmental stages, and biotic and abiotic (heat, drought, and salt) stresses provided insight into modus operandi of TaLRRKs during these conditions. Distinct expression of majority of stress responsive TaLRRKs homologous genes suggested their specified role in a particular condition. These results provided a comprehensive analysis of various characteristic features including functional divergence, which may provide the way for future functional characterization of this important gene family in bread wheat.

Highlights

The leucine rich repeat receptor like kinases (LRRKs) represent the largest subfamily of receptor like kinases (RLK), which are involved in diverse functions in plants (Shiu and Bleecker, 2001; Diévart and Clark, 2003; Shiu et al, 2004)
Most of the clusters consisted of at least one sequence from the homeologous chromosomes of A, B, and D sub-genomes, which might be considered as homeologous genes
The largest cluster (LRRK70) consisted of 20 homologous sequences, while 99 TaLRRK sequences were distinct without any homolog

Summary

INTRODUCTION

The leucine rich repeat receptor like kinases (LRRKs) represent the largest subfamily of receptor like kinases (RLK), which are involved in diverse functions in plants (Shiu and Bleecker, 2001; Diévart and Clark, 2003; Shiu et al, 2004). The LRR domain is stable among all proteins built from tandemly repeated motifs because of its hydrophobic solenoid inner core, where the conserved leucine and other aliphatic residues are present This structure favors the protein-protein interactions (Bella et al, 2008). The differential expression of LRRK genes during abiotic stresses in various plants like arabidopsis, rice, and potato has been reported (Diévart and Clark, 2004; Osakabe et al, 2005; Park et al, 2014; Wu et al, 2016). To the best of our knowledge, this is the first report on genome wide characterization of LRRK genes in T. aestivum

MATERIALS AND METHODS

RESULTS

DISCUSSION