title: Starch bioengineering affects cereal grain germination and seedling establishment.
abstract: Cereal grain germination is central for plant early development, and efficient germination has a major role in crop propagation and malting. Endosperm starch is the prime energy reserve in germination and seedling establishment. In this study, it was hypothesized that optimized starch granule structure, and not only the endosperm starch content per se, is important for germination and seedling establishment. For that purpose, wild-type (WT), and specifically engineered degradable hyperphosphorylated (HP) starch and more resistant amylose-only (AO) starch barley lines were used. The transgenics showed no severe phenotypes and the WT and HP lines degraded the starch similarly, having 30% residual starch after 12 d of germination. However, the AO line showed significant resistance to degradation, having 57% residual starch. Interestingly, protein and β-glucan (BG) degradation was stimulated for both HP and AO lines as compared with the WT. At late seedling establishment stages, specific sugars were rapidly consumed in the AO line. α-Amylase activity was distinctly suppressed in both the HP and the AO lines. Pre-germination β-amylase deposition was low in the AO grains and β-amylase was generally suppressed in both HP and AO lines throughout germination. As further supported by scanning electron microscopy and histochemical analyses on grain and seedlings, it was concluded that inadequate starch granule deposition in combination with the suppressed hydrolase activity leads to temporal and compensating re-direction of starch, sugar, and protein catabolism important to maintain metabolic dynamics during grain germination and seedling establishment.
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
authors.forename: Shahnoor S
authors.initials: SS
authors.lastname: Shaik
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark Department of Molecular Biology and Genetics, Aarhus University, Forsøgsvej 1, 4200 Slagelse, Denmark.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Carciofi
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
authors.forename: Helle J
authors.initials: HJ
authors.lastname: Martens
authors.affiliation: Department of Molecular Biology and Genetics, Aarhus University, Forsøgsvej 1, 4200 Slagelse, Denmark kim.hebelstrup@agrsci.dk abl@plen.ku.dk.
authors.forename: Kim H
authors.initials: KH
authors.lastname: Hebelstrup
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark kim.hebelstrup@agrsci.dk abl@plen.ku.dk.
authors.forename: Andreas
authors.initials: A
authors.lastname: Blennow
mesh_terms: D000688:Amylose / Q000378:metabolism; D057005:Bioengineering; D018525:Germination; D001467:Hordeum / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D012639:Seeds / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D013213:Starch / Q000096:biosynthesis*; D000516:alpha-Amylases / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D013213:Starch; D000688:Amylose; D000516:alpha-Amylases
keywords: Amylase; barley; cereal; germination; grain; starch.