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ARS Home » Midwest Area » West Lafayette, Indiana » Crop Production and Pest Control Research » Research » Publications at this Location » Publication #58898
Title: MOLECULAR AND BIOCHEMICAL COORDINATION OF STARCH BIOSYNTHESIS DURING BARLEY SEED DEVELOPMENT

Author
item ANDERSON, JOSEPH
item BUCHOLTZ, DENNIS - PURDUE UNIVERSITY
item GALLI, TERESA - MONTANA STATE UNIVERSITY
item Cook, Allen
item PETIK, JILL - MONTANA STATE UNIVERSITY

Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 5/6/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Starch metabolism in leaf tissue is strictly controlled by allosteric regulation at the enzymatic step catalyzed by ADPglucose pyrophosphorylase (AGPP). At this time it is not clear to what extent regulation of AGPP controls starch biosynthesis in non-photosynthetic tissue. To address these regulatory questions we have compared the amount of starch produced, enzyme activities of Sh and AGPP, and the level of mRNA accumulation of Sh both subunits of AGPP, and granular-bound starch synthase (Wxy) during barley seed development in four barley cultivars. The levels of all these measured parameters were very low at 4 days post anthesis (DPA) in each cultivar. The pattern of starch synthesis and Sh activity was similar through development with maximal levels of both being reached by 12 to 20 DPA. These levels remained relatively constant through development until 36 to 40 DPA (maturity, 10-28% moisture) when Sh activity dropped to a low minimal level indicating that the rate of starch synthesis also declined a this stage of development. AGPP activity reached a maximum at 12 to 16 DPA but, unlike Sh activity, then declined through the remainder of development and reached baseline levels by 36 DPA. The transcript levels of Sh and Exy followed the pattern of Sh enzyme activity and the transcript levels of the AGPP subunits also mimic AGPP enzyme activity except the transcript level of these genes increased before the appearance of significant enzyme activity. These results suggest that starch biosynthesis is regulated both genetically and biochemically by AGPP during barley seed development. This research is supported by the USDA-ARS.