title: Comparison of starch granule development and physicochemical properties of starches in wheat pericarp and endosperm.
abstract: BACKGROUND
  The objectives of this study were: (i) to characterize structural development of starch granule in pericarp and endosperm during wheat caryopsis growth; (ii) to compare physicochemical properties of starches in pericarp and endosperm; (iii) to further discover the relationships between pericarp starches and endosperm starches. Wheat pericarp and endosperm at different development stages were observed by light microscopy and scanning electron microscopy, respectively. Structural properties of starches were determined using X-ray power diffraction and (13) C solid nuclear magnetic resonance.
  
  
  RESULTS
  Pericarp starch granules (PSG) accumulated in amyloplasts and chloroplasts, and showed a typical accumulation peak at 5 days after fertilization (DAF), and then gradually decomposed during 5-22 DAF. PSG in the abdominal region showed a higher rate of decomposition compared to the dorsal region of pericarp. Endosperm starch granules (ESG) accumulated in amyloplasts, and occurred in endosperm cells at 5 DAF, then rapidly enriched the endosperm cells until 22 DAF. Compared with ESG, PSG were compound granules of irregular shape and small size distribution. The results also suggested lower amylose content and V-type single-helix content and higher proportions of double helices for PSG compared to ESG.
  
  
  CONCLUSIONS
  Based on the structural development of PSG and ESG, we speculated that the saccharides resulting from decomposition of PSG, on one hand, enabled the pericarp to survive before maturity of wheat caryopsis and, on the other hand, provided extra nutrition for the growth of ESG.
authors.affiliation: Key Laboratories of Crop Genetics and Physiology of the Jiangsu Province and Plant Functional Genomics of the Ministry of Education, Yangzhou University, Yangzhou, 225009, China.
authors.forename: Xurun
authors.initials: X
authors.lastname: Yu
authors.forename: Liang
authors.initials: L
authors.lastname: Zhou
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Heng
authors.initials: H
authors.lastname: Yu
authors.forename: Fei
authors.initials: F
authors.lastname: Xiong
authors.forename: Zhong
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000688:Amylose / Q000032:analysis; D055598:Chemical Phenomena; D056625:Endosperm / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D012639:Seeds / Q000737:chemistry / Q000648:ultrastructure*; D013213:Starch / Q000737:chemistry*; D013816:Thermodynamics; D014908:Triticum / Q000737:chemistry* / Q000254:growth & development* / Q000648:ultrastructure; D014961:X-Ray Diffraction
chemical_list: D013213:Starch; D000688:Amylose
keywords: development; endosperm starch granules; pericarp starch granules; structural property; wheat