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.

中文翻译：

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甘蓝型作物β-淀粉酶基因家族的全基因组分析和BnaBAM基因对非生物胁迫的响应

β-淀粉酶（BAM）基因家族以其将淀粉水解为麦芽糖单元的催化能力而闻名，已被认为在代谢和基因调控中起着至关重要的作用。迄今为止，尚未在油料作物中鉴定BAM基因。在这项研究中，全基因组的调查显示30个的识别BnaBAM基因甘蓝型油菜L.（甘蓝型油菜L.），11个BraBAM基因芜菁L.（芜菁L.），和20个BoBAM基因甘蓝型油菜（B. oleraceaL.），根据序列相似性和系统发育关系分为四个亚科。所有的BAM中的异源四倍体基因组中鉴定的基因的欧洲油菜，以及两个亲本相关的物种（芜菁和甘蓝），分析了该基因的结构，染色体分配和共线性。进一步应用了核心葡糖基水解酶结构域的序列比对，展示了六个候选β-淀粉酶（BnaBAM1，BnaBAM3.1-3.4和BnaBAM5）和25个β-淀粉酶样蛋白。目前的结果还表明，30个BnaBAMs，11个BraBAMs和17个BoBAMs的染色体分布不均匀。芸苔属作物。同一亚科中BAM基因的相似结构组成表明它们相对保守。非生物胁迫构成了全球植物生长和生产力的重要限制之一。因此，在油菜中分析了非生物胁迫下BnaBAM基因的响应性。表达模式揭示了所有成员的应激反应行为，其中BnaBAM3s更突出。这些差异表达模式表明环境刺激引起的BnaBAM的复杂调控。总而言之，本研究提供了对甘蓝型油菜BAM基因家族的初步见解作物，这为调查应激响应型BnaBAM候选物在甘蓝型油菜中的作用奠定了基础。