title: New starch phenotypes produced by TILLING in barley.
abstract: Barley grain starch is formed by amylose and amylopectin in a 1:3 ratio, and is packed into granules of different dimensions. The distribution of granule dimension is bimodal, with a majority of small spherical B-granules and a smaller amount of large discoidal A-granules containing the majority of the starch. Starch granules are semi-crystalline structures with characteristic X-ray diffraction patterns. Distinct features of starch granules are controlled by different enzymes and are relevant for nutritional value or industrial applications. Here, the Targeting-Induced Local Lesions IN Genomes (TILLING) approach was applied on the barley TILLMore TILLING population to identify 29 new alleles in five genes related to starch metabolism known to be expressed in the endosperm during grain filling: BMY1 (Beta-amylase 1), GBSSI (Granule Bound Starch Synthase I), LDA1 (Limit Dextrinase 1), SSI (Starch Synthase I), SSIIa (Starch Synthase IIa). Reserve starch of nine M3 mutant lines carrying missense or nonsense mutations was analysed for granule size, crystallinity and amylose/amylopectin content. Seven mutant lines presented starches with different features in respect to the wild-type: (i) a mutant line with a missense mutation in GBSSI showed a 4-fold reduced amylose/amylopectin ratio; (ii) a missense mutations in SSI resulted in 2-fold increase in A:B granule ratio; (iii) a nonsense mutation in SSIIa was associated with shrunken seeds with a 2-fold increased amylose/amylopectin ratio and different type of crystal packing in the granule; (iv) the remaining four missense mutations suggested a role of LDA1 in granule initiation, and of SSIIa in determining the size of A-granules. We demonstrate the feasibility of the TILLING approach to identify new alleles in genes related to starch metabolism in barley. Based on their novel physicochemical properties, some of the identified new mutations may have nutritional and/or industrial applications.
authors.affiliation: Department of Pharmacy and Biotechnology FABIT, University of Bologna, Bologna, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Sparla
authors.affiliation: Department of Chemistry "G. Ciamician", University of Bologna, Bologna, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Falini
authors.affiliation: Department of Agriculture, Forestry, Nature & Energy, University of Tuscia, Viterbo, Italy.
authors.forename: Ermelinda
authors.initials: E
authors.lastname: Botticella
authors.affiliation: Department of Pharmacy and Biotechnology FABIT, University of Bologna, Bologna, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Pirone
authors.affiliation: Department of Agricultural Sciences, University of Bologna, Bologna, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Talamè
authors.affiliation: Department of Agricultural Sciences, University of Bologna, Bologna, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Bovina
authors.affiliation: Department of Agricultural Sciences, University of Bologna, Bologna, Italy.
authors.forename: Silvio
authors.initials: S
authors.lastname: Salvi
authors.affiliation: Department of Agricultural Sciences, University of Bologna, Bologna, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Tuberosa
authors.affiliation: Department of Agriculture, Forestry, Nature & Energy, University of Tuscia, Viterbo, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Sestili
authors.affiliation: Department of Pharmacy and Biotechnology FABIT, University of Bologna, Bologna, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Trost
mesh_terms: D000688:Amylose / Q000378:metabolism; D023281:Genomics / Q000379:methods; D001467:Hordeum / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D010940:Plant Proteins; D012639:Seeds / Q000033:anatomy & histology / Q000235:genetics; D013213:Starch / Q000378:metabolism*; D013214:Starch Synthase
chemical_list: D010940:Plant Proteins; D013213:Starch; D000688:Amylose; C111377:starch synthase II; D013214:Starch Synthase