title: Differences between easy- and difficult-to-mill chickpea (Cicer arietinum L.) genotypes. Part III: free sugar and non-starch polysaccharide composition.
abstract: BACKGROUND
  Parts I and II of this series of papers identified several associations between the ease of milling and the chemical compositions of different chickpea seed fractions. Non-starch polysaccharides were implicated; hence, this study examines the free sugars and sugar residues.
  
  
  RESULTS
  Difficult milling is associated with: (1) lower glucose and xylose residues (less cellulose and xyloglucans) and more arabinose, rhamnose and uronic acid in the seed coat, suggesting a more flexible seed coat that resists cracking and decortication; (2) a higher content of soluble and insoluble non-starch polysaccharide fractions in the cotyledon periphery, supporting a pectic polysaccharide mechanism comprising arabinogalacturonan, homogalacturonan, rhamnogalalcturonan, and glucuronan backbone structures; (3) higher glucose and mannose residues in the cotyledon periphery, supporting a lectin-mediated mechanism of adhesion; and (4) higher arabinose and glucose residues in the cotyledon periphery, supporting a mechanism involving arabinogalactan-proteins.
  
  
  CONCLUSIONS
  This series has shown that the chemical composition of chickpea does vary in ways that are consistent with physical explanations of how seed structure and properties relate to milling behaviour. Seed coat strength and flexibility, pectic polysaccharide binding, lectins and arabinogalactan-proteins have been implicated. Increased understanding in these mechanisms will allow breeding programmes to optimise milling performance in new cultivars.
authors.affiliation: NSW Department of Primary Industries, Tamworth Agricultural Institute, 4 Marsden Park Rd, Calala, NSW 2340, Australia.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Wood
authors.forename: Edmund J
authors.initials: EJ
authors.lastname: Knights
authors.forename: Grant M
authors.initials: GM
authors.lastname: Campbell
authors.forename: Mingan
authors.initials: M
authors.lastname: Choct
mesh_terms: D000268:Adhesiveness; D001089:Arabinose / Q000032:analysis / Q000096:biosynthesis; D029863:Cicer / Q000737:chemistry* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018548:Cotyledon / Q000737:chemistry* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018556:Crops, Agricultural / Q000737:chemistry* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D003433:Crosses, Genetic; D004040:Dietary Carbohydrates / Q000032:analysis* / Q000378:metabolism; D019422:Dietary Sucrose / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D005511:Food Handling; D005838:Genotype; D006801:Humans; D009517:New South Wales; D009753:Nutritive Value; D019441:Plant Epidermis / Q000737:chemistry* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011134:Polysaccharides / Q000032:analysis / Q000096:biosynthesis; D012210:Rhamnose / Q000032:analysis / Q000096:biosynthesis; D012639:Seeds / Q000737:chemistry* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D012995:Solubility; D014574:Uronic Acids / Q000032:analysis / Q000737:chemistry / Q000378:metabolism
chemical_list: D004040:Dietary Carbohydrates; D019422:Dietary Sucrose; D011134:Polysaccharides; D014574:Uronic Acids; D001089:Arabinose; D012210:Rhamnose
keywords: Cicer arietinum; adhesion; dehulling splitting behaviour; grain legume; pectic polysaccharides; seed structure