Background: 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.
Results: In this study, the genome wide survey revealed the identification of 30 BnaBAM genes in Brassica napus (B. napus), 11 BraBAM genes in Brassica rapa (B. rapa), 20 BoBAM genes in Brassica oleracea (B. oleracea), which were divided into 4 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. 30 BnaBAMs, 11 BraBAMs and 17 BoBAMs exhibited uneven distribution on chromosomes of Brassica crops. The similar structural compositions of BAM genes in the same subfamily suggested that they were relatively conserved. Abiotic stresses pose one of the major constraints to plant growth and productivity worldwide. Thus, the responsiveness of BnaBAM genes under abiotic stresses were analyzed in B. napus. The expression patterns revealed a stress responsive behavior of all members, of which BnaBAM3s were more prominent. These differential expression patterns suggested an intricate regulation of BnaBAMs elicited by environmental stimuli.
Conclusion: 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.