Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2008
Publication Date: 9/15/2008
Citation: Taliercio, E.W. 2008. Isolation and characterization of an ADP-glucose pyrophosphorylase gene from Gossypium hirsutum L. Journal of Cotton Science. 1:273-279. Interpretive Summary: Cotton stores starch in its stems and roots that is redistributed to developing bolls to support seed and fiber development. Accumulation of starch in cotton stems and roots is likely to play an important role in cotton development. A gene encoding a cotton ADP-glucose pyrophosphorylase (ADPGp) gene was isolated, sequenced and characterized. ADPGp is an important enzyme controlling starch biosynthesis. The gene had a structure consisting of 8 introns and 9 exons, similar to other plant AGPGp genes. The protein that the gene encoded also had many features similar to other plant ADPGp including a variable amino end, conserved catalytic sites and conserved amino acid sequences that control enzyme activity. This gene was abundantly expressed in starch storing roots and in leaves. Analysis of the promoter region identified part of the basal promoter and identified sequences indicating that expression of this gene may respond to the phytohormone, Abscisic acid.
Technical Abstract: Roots and stems of cotton (Gossypium hirsutum L.) plants store photoassimilate as starch. Starch stored prior to flowering appears to be mobilized from stems and roots to support seed and fiber development, although it is possible that stems and roots compete with seed for photoassimilate. Partitioning of fixed carbon between starch in vegetative storage tissues and seed is likely to impact cotton development and yield. The enzyme ADPGp plays a rate limiting role in starch production and its temporal and spatial expression plays a critical role in determining patterns of starch deposition in plants. Therefore a cotton gene encoding ADPGp was isolated, sequenced and analyzed. The gene was composed of 8 introns and 9 exons. The introns were bound by typical splice sites. The ORF encoded a peptide of 518 amino acids with many catalytic and regulatory features common to plant ADPGp. This gene was abundantly expressed in starchy-roots and in leaves. Expression of this gene was low in developing fiber. Analysis of the promoter sequence suggested this gene may be regulated by ABA. This promoter should be useful for targeting gene expression in starch accumulating tissues.