Structural and regulatory differences in amylase isoenzymes in germinating Brazilian barley cultivars

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

The amylase electrophoretic patterns of 10 Brazilian brewing-barley varieties with different malting grades and diastatic power were analyzed during the 7-day germination which occurs during the malting process. Intra and inter-variety genetic variability was observed at both the structural and regulatory level. In the first few days after germination all varieties showed a few active loci, all of them with low activity. In subsequent days, new loci became active and those already detected since early germination showed increased activity. All varieties showed a continuous increase in amylase synthesis until the 3rd and/or 4th day after germination. Some varieties maintained high amylase activity until the last day of germination, while others showed a decrease in activity on the 5th or 6th day. No specific band increased or decreased its intensity independently of the others. A total of 14 loci were detected, out of which only one locus was polymorphic, indicating very low structural genetic variability, with only 2.8% polymorphic loci, an average of 1.04 alleles per loci, and an average expected heterozygosity of only 0.7%. The mean intra-variety Jaccard similarity coefficient complement (1 - SJ) was 0.009. The mean intra-variety difference based on regulatory differences was higher (1 - SJ = 0.17) than that obtained based on structural differences, suggesting differential gene activation. Inter-variety differentiation also showed low structural variability, with 1 - SJ = 0.026 and a Nei genetic distance (D) value of 0.0076, and a remarkable increase in divergence caused by differential gene activation (1 - SJ = 0.34). These results indicate that regulatory polymorphism is the principal agent responsible for amylase variability in the barley varieties analyzed.

ASSUNTO(S)

barley genética amylases amilase isoenzymes cevada structural and regulatory genetic differences. isoenzima

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