AUTHOR=Subburaj Saminathan , Zhu Dong , Li Xiaohui , Hu Yingkao , Yan Yueming 

TITLE=Molecular Characterization and Expression Profiling of Brachypodium distachyon L. Cystatin Genes Reveal High Evolutionary Conservation and Functional Divergence in Response to Abiotic Stress

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00743

DOI=10.3389/fpls.2017.00743

ISSN=1664-462X

ABSTRACT=<p>Cystatin is a class of proteins mainly involved in cysteine protease inhibition and plant growth and development, as well as tolerance under various abiotic stresses. In this study, we performed the first comprehensive analysis of the molecular characterization and expression profiling in response to various abiotic stresses of the cystatin gene family in <italic>Brachypodium distachyon</italic>, a novel model plant for <italic>Triticum</italic> species with huge genomes. Comprehensive searches of the <italic>Brachypodium</italic> genome database identified 25 <italic>B. distachyon cystatin</italic> (<italic>BdC</italic>) genes that are distributed unevenly on chromosomes; of these, nine and two were involved in tandem and segmental duplication events, respectively. All <italic>BdC</italic> genes had similar exon/intron structural organization, with three conserved motifs similar to those from other plant species, indicating their high evolutionary conservation. Expression profiling of 10 typical <italic>BdC</italic> genes revealed ubiquitous expression in different organs at varying expression levels. <italic>BdC</italic> gene expression in seedling leaves was particularly highly induced by various abiotic stresses, including the plant hormone abscisic acid and various environmental cues (cold, H<sub>2</sub>O<sub>2</sub>, CdCl<sub>2</sub>, salt, and drought). Interestingly, most <italic>BdC</italic> genes were significantly upregulated under multiple abiotic stresses, including <italic>BdC15</italic> under all stresses, <italic>BdC7-2</italic> and <italic>BdC10</italic> under five stresses, and <italic>BdC7-1, BdC2-1, BdC14</italic>, and <italic>BdC12</italic> under four stresses. The putative metabolic pathways of cytastin genes in response to various abiotic stresses mainly involve the aberrant protein degradation pathway and reactive oxygen species (ROS)-triggered programmed cell death signaling pathways. These observations provide a better understanding of the structural and functional characteristics of the plant cystatin gene family.</p>