Submitted to: North American Barley Research Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 29, 2008
Publication Date: October 26, 2008
Citation: Vinje, M.A., Willis, D.K., Duke, S.H., Henson, C.A. 2008. Differential RNA Expression of Two Barley ß-Amylase Genes (Bmy1 and Bmy2) in Developing Grains and Their Association with ß-Amylase Activity [abstract]. North American Barley Research Workshop Proceedings. p. 37. Technical Abstract: RNA expression from the barley ß-amylase1 (Bmy1) gene was determined during seed development in four genotypes (Legacy, Harrington, Ashqelon, and PI 296897). The Bmy1 transcript amount in Legacy and Harrington was not significantly different at 17, 19, or 21 days after anthesis (DAA). Ashqelon Bmy1 expression is around three-fold higher than Legacy and Harrington at 17, 19, and 21 DAA. The Bmy1 expression in PI 296897 is around 40-fold lower than Legacy and Harrington at 17 and 21 DAA and around 24-fold lower than Legacy and Harrington at 19 DAA. PI 296897 had over 100-fold lower Bmy1 RNA levels at 17 and 21 DAA and 76-fold lower Bmy1 expression at 19 DAA than Ashqelon. ß-Amylase activity was measured to determine if the expression levels were comparable to activity. Harrington had 2.9, 2.6, and 2.1-fold lower activity at 17, 19, and 21 DAA than Legacy even though their Bmy1 transcript levels were the same. The ß-amylase activity levels of Legacy and Harrington at maturity were the same. The peak expression of Bmy1 in Harrington was not ascertained because the Bmy1 expression at 19 DAA was statistically the same as the Bmy1 expression at 21 DAA. The discrepancy between ß-amylase activity in Harrington at 21 DAA and at maturity indicated that Bmy1 transcript levels may peak later or it Bmy1 is expressed over a longer time period than occurs in Legacy and/or other genotypes. Ashqelon had three-fold higher Bmy1 expression than Legacy and Harrington and had higher ß-amylase activity. PI 296897 had higher ß-amylase activity at all developmental time points and at maturity than Legacy and Harrington despite having between 24 and 44-fold lower Bmy1 transcript levels. This discrepancy led us to determine the RNA levels of Bmy2, which is known to be expressed in early seed development. Bmy2 expression is very low in Legacy and Harrington at 17, 19, and 21 DAA indicating that it probably is not contributing significantly to the total ß-amylase activity. Bmy2 transcript levels in Ashqelon were not significantly different from Legacy or Harrington. Bmy1 expression seems to be the major contributor to ß-amylase activity in the time points measured for Legacy, Harrington, and Ashqelon. PI 296897 has between 3 and 11-fold higher Bmy2 expression at 17, 19, and 21 DAA than the other three genotypes. These data lead us to propose that the expression of Bmy2 is contributing more ß-amylase activity in PI 296897 by being expressed later in seed development.