ABSTRACT
Six commercial U.K. cultivars of winter wheat selected to represent different abilities to partition nitrogen into grain protein were grown in replicated field trials at five different sites over three seasons. The proportion of LMW glutenin subunits decreased and the proportion of gliadins increased during grain development and in response to N application. Differences were observed between the proportions of LMW glutenin subunits and gliadins in low- and high-protein grain, these two fractions being decreased and increased, respectively. There was little effect of grain protein content on the proportions of either the HMW glutenin subunits or large glutenin polymers, which are enriched in these subunits, with the latter increasing during development in all cultivars. The proportion of total protein present in polymers in the mature grain decreased with increasing N level. Correlations were also observed between the abundances of gliadin protein transcripts and the corresponding proteins.
Subject(s)
Nitrogen/analysis , Plant Proteins/metabolism , Triticum/chemistry , Gene Expression Regulation, Plant , Genotype , Nitrogen/metabolism , Plant Proteins/genetics , Seasons , Seeds/chemistry , Seeds/genetics , Seeds/growth & development , Seeds/metabolism , Triticum/genetics , Triticum/growth & development , Triticum/metabolismABSTRACT
The occurrence and roles of cGMP were investigated in aleurone layers and protoplasts isolated from barley (cv Himalaya) grain. Levels of cGMP in freshly isolated barley aleurone layers ranged from 0.065 to 0.08 pmol/g fresh weight of tissue, and cGMP levels increased transiently after incubation in gibberellic acid (GA). Abscisic acid (ABA) did not increase cGMP levels in aleurone layers. LY 83583 (LY), an inhibitor of guanylyl cyclase, prevented the GA-induced increase in cGMP and inhibited GA-induced [alpha]-amylase synthesis and secretion. The inhibitory effects of LY could be overcome by membrane-permeant analogs of cGMP. LY also prevented GA-induced accumulation of [alpha]-amylase and GAMYB mRNAs. cGMP alone was not sufficient to induce the accumulation of [alpha]-amylase or GAMYB mRNA. LY had a less dramatic effect on the accumulation of mRNAs encoding the ABA-responsive gene Rab21. We conclude that cGMP plays an important role in GA, but not ABA, signaling in the barley aleurone cell.
