ORIGINAL PAPER Gibberellic acid-insensitive semi-dwarfs of Triticum dicoccum have delayed aleurone function Chun Mei Chang • Alka Gupta • Suresh G. Bhagwat Received: 4 April 2013 / Accepted: 8 May 2014 Ó Springer Science+Business Media Dordrecht 2014 Abstract Aleurone tissue is known for its function of secreting a number of hydrolytic enzymes including a- amylases, nucleases and proteases in response to gibber- ellic acid (GA). The effect of GA on aleurone tissue function was studied in Triticum dicoccum including a tall variety, its semi-dwarf mutant and a semi-dwarf variety carrying RhtB1b allele, using isolated aleurone layers. A comparison of the tall and semi-dwarfs revealed that there was a decrease in the amount of a-amylase secreted and also a delay in its stimulation in the two semi-dwarfs. a- Amylase secretion exhibited a peak when the amount of a- amylase activity secreted was plotted as a function of time interval. The semi-dwarfs showed a delay in the appear- ance of the peak indicating that there was a delay in their response to GA treatment. Presence of GA also caused increased aleurone mitochondrial activity and enhanced loss of nitrogen and dry weight. Delays were also observed in time required to attain the peaks of the mitochondrial activity of the aleurone layer, total protein secreted in the medium, total loss in nitrogen and dry weight from the aleurone layer. The pattern of aleurone function was sim- ilar in both the semi-dwarfs, however, there was a greater delay in aleurone function in the new mutant as compared to the RhtB1b semi-dwarf. The altered GA signaling due to mutation(s) in the two GA insensitive semi-dwarfs may have resulted in a delay in attaining peak activity of the aleurone layers. Keywords a-Amylase Á DELLA Á GA-insensitive semi- dwarf Á RhtB1b mutant Á Nitrogen content Á Weight loss Á Mitochondrial activity Á Transcriptional factors Á Ploidy level Abbreviations GA Gibberellic acid PIF Phytochrome interacting factor PSV Protein storage vacuole TF Transcriptional factor TTC Triphenyl tetrazolium chloride Introduction Gibberellic acids (GAs) induce a wide range of plant growth responses including seed germination, hypocotyl elongation, stem elongation, leaf expansion, pollen matu- ration and induction of flowering (Olszewski et al. 2002). GAs act on the dormant cereal aleurone and cause the release of a battery of hydrolytic enzymes including the amylases, proteases and nucleases (Baulcombe et al. 1986; Fath et al. 2000) that mobilize the endosperm reserves providing nourishment to the growing seedling (Mrva et al. 2006). Among the enzymes secreted in response to GA, stimulation of a-amylase is the most widely studied func- tion of cereal aleurone layers. GA-induced a-amylase gene expression in aleurone cells of germinating cereal grains is a useful model system to study the GA response pathway (Olszewski et al. 2002). Electronic supplementary material The online version of this article (doi:10.1007/s10725-014-9934-8) contains supplementary material, which is available to authorized users. C. M. Chang Á S. G. Bhagwat (&) Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, India e-mail: sgb1953@gmail.com A. Gupta Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai, India 123 Plant Growth Regul DOI 10.1007/s10725-014-9934-8