title: Dynamic development of starch granules and the regulation of starch biosynthesis in Brachypodium distachyon: comparison with common wheat and Aegilops peregrina.
abstract: BACKGROUND
  Thorough understanding of seed starch biosynthesis and accumulation mechanisms is of great importance for agriculture and crop improvement strategies. We conducted the first comprehensive study of the dynamic development of starch granules and the regulation of starch biosynthesis in Brachypodium distachyon and compared the findings with those reported for common wheat (Chinese Spring, CS) and Aegilops peregrina.
  
  
  RESULTS
  Only B-granules were identified in Brachypodium Bd21, and the shape variation and development of starch granules were similar in the B-granules of CS and Bd21. Phylogenetic analysis showed that most of the Bd21 starch synthesis-related genes were more similar to those in wheat than in rice. Early expression of key genes in Bd21 starch biosynthesis mediate starch synthesis in the pericarp; intermediate-stage expression increases the number and size of starch granules. In contrast, these enzymes in CS and Ae. peregrina were mostly expressed at intermediate stages, driving production of new B-granules and increasing the granule size, respectively. Immunogold labeling showed that granule-bound starch synthase (GBSSI; related to amylose synthesis) was mainly present in starch granules: at lower levels in the B-granules of Bd21 than in CS. Furthermore, GBSSI was phosphorylated at threonine 183 and tyrosine 185 in the starch synthase catalytic domain in CS and Ae. peregrina, but neither site was phosphorylated in Bd21, suggesting GBSSI phosphorylation could improve amylose biosynthesis.
  
  
  CONCLUSIONS
  Bd21 contains only B-granules, and the expression of key genes in the three studied genera is consistent with the dynamic development of starch granules. GBSSI is present in greater amounts in the B-granules of CS than in Bd21; two phosphorylation sites (Thr183 and Tyr185) were found in Triticum and Aegilops; these sites were not phosphorylated in Bd21. GBSSI phosphorylation may reflect its importance in amylose synthesis.
authors.forename: Guanxing
authors.initials: G
authors.lastname: Chen
authors.forename: Jiantang
authors.initials: J
authors.lastname: Zhu
authors.forename: Jianwen
authors.initials: J
authors.lastname: Zhou
authors.forename: Saminathan
authors.initials: S
authors.lastname: Subburaj
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
authors.forename: Caixia
authors.initials: C
authors.lastname: Han
authors.forename: Pengchao
authors.initials: P
authors.lastname: Hao
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Li
authors.forename: Yueming
authors.initials: Y
authors.lastname: Yan
mesh_terms: D000595:Amino Acid Sequence; D015153:Blotting, Western; D058431:Brachypodium / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D032461:Chromosomes, Plant; D015870:Gene Expression; D017343:Genes, Plant; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010802:Phylogeny; D012639:Seeds / Q000254:growth & development / Q000378:metabolism*; D013213:Starch / Q000096:biosynthesis*; D013214:Starch Synthase / Q000378:metabolism; D014908:Triticum / Q000378:metabolism*
chemical_list: D013213:Starch; D013214:Starch Synthase
references.citation: Plant Physiol. 1975 May;55(5):881-9
references.pmid: 16659185
references.citation: Plant Physiol. 1998 Oct;118(2):451-9
references.pmid: 9765530
references.citation: Plant J. 2001 Mar;25(5):475-86
references.pmid: 11309138
references.citation: Plant Physiol. 2008 Apr;146(4):1878-91
references.pmid: 18263778
references.citation: J Exp Bot. 2008;59(12):3395-406
references.pmid: 18653693
references.citation: BMC Mol Biol. 2009 Feb 20;10:11
references.pmid: 19232096
references.citation: Histochemistry. 1981;71(1):81-8
references.pmid: 6785260
references.citation: J Exp Bot. 2010 Mar;61(5):1469-82
references.pmid: 20156842
references.citation: Plant Physiol. 2001 Dec;127(4):1539-55
references.pmid: 11743099
references.citation: Biopolymers. 2002 Jan;63(1):41-58
references.pmid: 11754347
references.citation: BMC Plant Biol. 2012 Nov 21;12:221
references.pmid: 23171363
references.citation: Plant Physiol. 2009 May;150(1):190-204
references.pmid: 19321714
references.citation: Plant Cell. 1998 Mar;10(3):399-412
references.pmid: 9501113
references.citation: Funct Integr Genomics. 2008 May;8(2):149-64
references.pmid: 18210171
references.citation: Plant Cell. 2008 Dec;20(12):3448-66
references.pmid: 19074683
references.citation: J Exp Bot. 2000 Aug;51(349):1357-61
references.pmid: 10944148
references.citation: Mol Biol Evol. 2009 Jul;26(7):1651-61
references.pmid: 19395588
references.citation: Arch Biochem Biophys. 1997 Jun 1;342(1):92-8
references.pmid: 9185617
references.citation: Curr Opin Plant Biol. 2005 Apr;8(2):204-10
references.pmid: 15753002
references.citation: Funct Integr Genomics. 2014 Mar;14(1):149-60
references.pmid: 24318766
references.citation: Annu Rev Plant Biol. 2003;54:207-33
references.pmid: 14502990
references.citation: Plant J. 2007 Feb;49(4):704-17
references.pmid: 17270010
references.citation: Nature. 2010 Feb 11;463(7282):763-8
references.pmid: 20148030
references.citation: Plant Mol Biol. 2004 Apr;54(6):865-79
references.pmid: 15604657
references.citation: Plant J. 2005 Aug;43(3):398-412
references.pmid: 16045475
references.citation: Plant Cell. 2004 Mar;16(3):694-708
references.pmid: 14973170
references.citation: Plant Physiol. 2006 Mar;140(3):1070-84
references.pmid: 16443699
references.citation: Plant Physiol. 2001 Oct;127(2):459-72
references.pmid: 11598221
references.citation: J Exp Bot. 2011 Mar;62(6):2217-28
references.pmid: 21227932
references.citation: J Proteome Res. 2010 Jun 4;9(6):3299-310
references.pmid: 20481496
references.citation: Plant J. 2007 Feb;49(3):492-504
references.pmid: 17217470
references.citation: Mol Biol Evol. 2007 Aug;24(8):1596-9
references.pmid: 17488738
references.citation: Plant J. 2006 Jul;47(2):310-27
references.pmid: 16771774
references.citation: Cell. 2013 Apr 25;153(3):640-53
references.pmid: 23622247
references.citation: Methods Mol Biol. 2007;355:15-25
references.pmid: 17093298
references.citation: Plant Physiol. 2000 Jan;122(1):255-64
references.pmid: 10631269
references.citation: Genetics. 2008 Sep;180(1):93-101
references.pmid: 18757939
references.citation: Anal Bioanal Chem. 2012 Jan;402(3):1297-313
references.pmid: 22080421
references.citation: J Exp Bot. 2012 Jan;63(2):739-55
references.pmid: 22016425
references.citation: Proteomics. 2009 Mar;9(6):1451-68
references.pmid: 19235172
references.citation: Nucleic Acids Res. 1994 Nov 11;22(22):4673-80
references.pmid: 7984417
references.citation: J Appl Genet. 2014 Feb;55(1):27-42
references.pmid: 24306693