Differential expression of two β-amylase genes (Bmy1 and Bmy2) in developing and mature barley grain

Abstract

Two barley (Hordeum vulgare L.) β-amylase genes (Bmy1 and Bmy2) were studied during the late maturation phase of grain development in four genotypes. The Bmy1 and Bmy2 DNA and amino acid sequences are extremely similar. The largest sequence differences are in the introns, seventh exon, and 3' UTR. Accumulation of Bmy2 mRNA was examined in developing grain at 17, 19, and 21 days after anthesis (DAA). One genotype, PI 296897, had significantly higher Bmy2 RNA transcript accumulation than the other three genotypes at all developmental stages. All four genotypes had Bmy2 mRNA levels decrease from 17 to 19 DAA, and remain the same from 19 to 21 DAA. Levels of Bmy1 mRNA were twenty thousand to over one hundred thousand times more than Bmy2 mRNA levels in genotypes Legacy, Harrington, and Ashqelon at all developmental stages and PI 296897 at 19 and 21 DAA. PI 296897 had five thousand times more Bmy1 mRNA than Bmy2 mRNA at 17 DAA. However, Bmy2 protein was not found at 17 DAA in any genotype. The presence of Bmy2 was immunologically detected at 19 DAA and was present in greater amounts at 21 DAA. Also, Bmy2 protein was found to be stored in mature grain and localized in the soluble fraction. However, Bmy1 protein was far more prevalent than Bmy2 at all developmental stages in all genotypes. Thus, the vast majority of β-amylase activity in developing and mature grain can be attributed to endosperm-specific β-amylase.

Validation of the β-amy1 Transcription Profiling Assay and Selection of Reference Genes Suited for a RT-qPCR Assay in Developing Barley Caryopsis

“…Both assays are fully consistent to each other and the protein assay validates transcription assay results. A high expression of β-amy1 17, 19 and 21st day after anthesis was very recently reported by Vinje et al [54]. They investigated four cultivars differing in the degree of expression; however, they included genotypes with different alleles and genetic backgrounds [55], whereas for assay validation, we selected three spring malting barley cultivars with similar pedigree and identical allele [23].…”

Mutagenesis of barley malting quality QTLs with Ds transposons

“…Previously, genome-wide gene expression studies have identified candidate genes affecting malting. Expression studies using qPCR (Potokina et al 2006;Vinje et al 2011), Microarray (Close et al 2004Potokina et al 2004;Watson and Henry 2005) and LongSAGE (White et al 2008) have shown the likely role of many malting genes such as α and β amylase, Cxp1. at different stages of seed germination.…”

Genome-wide identification and expression analysis of the β-amylase genes strongly associated with fruit development, ripening, and abiotic stress response in two banana cultivars

“…Thus, it is necessary to understand the mechanisms involved in banana fruit development. The BAM family has been reported to participate in the plant development of many species such as apple [39] , Arabidopsis [17] , barley [18] , and rye [40] . In apple, the amount of BAM protein was markedly greater during fruit development [39] .…”

“…Two BAM genes in Arabidopsis regulate shoot development [17] . The expression of a distinct transcript, from the barley Bmy1 gene, suggested its potential involvement in grain development [18] . In rye, expression of two BAM genes changed significantly during seed development [40] .…”

“…Overexpression of BAM7 and BAM8 in Arabidopsis controlled shoot growth and development through crosstalk with brassinosteroid signaling [17] . Expression of Bmy1 gene in endosperm was involved in the development and maturation of barley grain [18] . In addition, expression analyses of the BAM gene family in various species indicated that its expression is altered in response to various abiotic stresses, such as cold, salt or drought [19][20][21] .…”