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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Deficiency of maize starch-branching enzyme i results in altered starch fine structure, decreased digestibility and reduced coleoptile growth during germination | Xia et al. BMC Plant Biology 2011 11 95 http www.biomedcentral.com 1471-2229 11 95 BMC Plant Biology RESEARCH ARTICLE Open Access Deficiency of maize starch-branching enzyme i results in altered starch fine structure decreased digestibility and reduced coleoptile growth during germination Huan Xia1 3 Marna Yandeau-Nelson2 4 Donald B Thompson3 and Mark J Guiltinan4 Abstract Background Two distinct starch branching enzyme SBE isoforms predate the divergence of monocots and dicots and have been conserved in plants since then. This strongly suggests that both SBEI and SBEII provide unique selective advantages to plants. However no phenotype for the SBEI mutation sbela had been previously observed. To explore this incongruity the objective of the present work was to characterize functional and molecular phenotypes of both sbela and wild-type Wt in the W64A maize inbred line. Results Endosperm starch granules from the sbela mutant were more resistant to digestion by pancreatic a-amylase and the sbela mutant starch had an altered branching pattern for amylopectin and amylose. When kernels were germinated the sbela mutant was associated with shorter coleoptile length and higher residual starch content suggesting that less efficient starch utilization may have impaired growth during germination. Conclusions The present report documents for the first time a molecular phenotype due to the absence of SBEI and suggests strongly that it is associated with altered physiological function of the starch in vivo. We believe that these results provide a plausible rationale for the conservation of SBEI in plants in both monocots and dicots as greater seedling vigor would provide an important survival advantage when resources are limited. Background The starch granule is a highly-ordered structure with alternating crystalline and amorphous growth rings 1 2 . Starch molecules are biopolymers of anhydroglucose units linked by a-1 4 and a-1 6 glycosidic bonds. They are composed of two .
