Genome-Wide Analysis of the β-Amylase Gene Family in Brassica L. Crops and Expression Profiles of BnaBAM Genes in Response to Abiotic Stresses

Dan Luo,Yan Lv,Xiling Zou,Yong Cheng,Ziqi Jia

doi:10.3390/agronomy10121855

Abstract

The β-amylase (BAM) gene family, known for their property of catalytic ability to hydrolyze starch to maltose units, has been recognized to play critical roles in metabolism and gene regulation. To date, BAM genes have not been characterized in oil crops. In this study, the genome-wide survey revealed the identification of 30 BnaBAM genes in Brassica napus L. (B. napus L.), 11 BraBAM genes in Brassica rapa L. (B. rapa L.), and 20 BoBAM genes in Brassica oleracea L. (B. oleracea L.), which were divided into four subfamilies according to the sequence similarity and phylogenetic relationships. All the BAM genes identified in the allotetraploid genome of B. napus, as well as two parental-related species (B. rapa and B. oleracea), were analyzed for the gene structures, chromosomal distribution and collinearity. The sequence alignment of the core glucosyl-hydrolase domains was further applied, demonstrating six candidate β-amylase (BnaBAM1, BnaBAM3.1-3.4 and BnaBAM5) and 25 β-amylase-like proteins. The current results also showed that 30 BnaBAMs, 11 BraBAMs and 17 BoBAMs exhibited uneven distribution on chromosomes of Brassica L. crops. The similar structural compositions of BAM genes in the same subfamily suggested that they were relatively conserved. Abiotic stresses pose one of the significant constraints to plant growth and productivity worldwide. Thus, the responsiveness of BnaBAM genes under abiotic stresses was analyzed in B. napus. The expression patterns revealed a stress-responsive behaviour of all members, of which BnaBAM3s were more prominent. These differential expression patterns suggested an intricate regulation of BnaBAMs elicited by environmental stimuli. Altogether, the present study provides first insights into the BAM gene family of Brassica crops, which lays the foundation for investigating the roles of stress-responsive BnaBAM candidates in B. napus.

Highlights

Abiotic stresses reduce plant growth, productivity and quality, which leads to great economic loss for the farming community
The full-length protein sequences of 9 AtBAMs in Arabidopsis were used as BLAST queries against the Brassica crops genomics database
Sets of genes in B. napus, including BnaCBF17, LEA3, BnSIP1-1, B. napus is the most productive and widely planted species among three oilseed rapes

Summary

Introduction

Abiotic stresses reduce plant growth, productivity and quality, which leads to great economic loss for the farming community. The starch content of leaf is found to be decreased under drought [4,5,6,7], osmotic [8,9], extreme temperature [10,11], salt [12,13], and oxidative stress conditions [14]. These changes are accompanied by released sugars and other derived metabolites, that function as compatible solutes to protect against the damage caused by Agronomy 2020, 10, 1855; doi:10.3390/agronomy10121855 www.mdpi.com/journal/agronomy

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