title: Effect of wide variation of the Waxy gene on starch properties in hull-less barley from Qinghai-Tibet plateau in China.
abstract: Granule-bound starch synthase I (GBSS I) plays an important role in the synthesis of amylose and in the determination of starch properties in barley grains. Genomic DNAs for the Waxy gene encoding GBSS I protein were sequenced from 34 barley accessions or lines from Qinghai-Tibet plateau in China, to identify Waxy gene nucleotide variations and study the roles of polymorphic sites of the Waxy gene on expression levels of Waxy transcripts and GBSS I proteins and on resulting starch properties. A total of 116 DNA polymorphic sites were identified within the barley Waxy gene, which divided the studied accessions into 11 haplotypes. Among 33 nucleotide polymorphic sites in coding regions, 5 SNPs in three exons were found to play different roles on the expression level of the Waxy transcript and the GBSS I protein and on the amylose content and starch properties. One SNP G(3935)-to-T substitution in the 10th exon in the accession Z999 (HP II-2) caused a high expression level of the Waxy transcript and the GBSS I protein and the amylose free phenotype. The other SNP alteration was a C(2453)-to-T in the fifth exon in the accession Z1191 (HP I-5), which drastically reduced the expression level of the Waxy transcript and the GBSS I protein and, finally, produced the amylose free phenotype. Three SNPs in the seventh exon in the accession Z1337 (HP I-6) did not significantly change the level of Waxy transcript, the GBSS I protein, and starch properties, except obviously reducing the breakdown value of starch viscosity and extending the peak time. A total of 84 DNA polymorphic sites were found in the noncoding regions. A 403 bp deletion at 5'UTR in the accession Z1979 (HP I-3) had low transcript level, low GBSS I protein level, and low amylose content due to the deletion of cis-acting DNA regulatory elements. A 191 bp insertion and a 15 bp insertion in the first intron and second exons, respectively, may be closely related to a higher transcript level of the Waxy gene and significant differences in some starch properties of the Waxy I DNA group as compared to the Waxy II DNA group. This study indicates the specific variations of the Waxy gene have a great effect on amylose synthesis and starch properties of hull-less barley, which could be very useful to produce new barley with variable starch properties.
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences , No. 9 Section 4, Renmin South Road, Chengdu 610041, People's Republic of China.
authors.forename: Qiao
authors.initials: Q
authors.lastname: Li
authors.forename: Zhifen
authors.initials: Z
authors.lastname: Pan
authors.forename: Guangbing
authors.initials: G
authors.lastname: Deng
authors.forename: Hai
authors.initials: H
authors.lastname: Long
authors.forename: Zhongyi
authors.initials: Z
authors.lastname: Li
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Deng
authors.forename: JunJun
authors.initials: J
authors.lastname: Liang
authors.forename: Yawei
authors.initials: Y
authors.lastname: Tang
authors.forename: Xingquan
authors.initials: X
authors.lastname: Zeng
authors.forename: Nyima
authors.initials: N
authors.lastname: Tashi
authors.forename: Maoqun
authors.initials: M
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D000688:Amylose / Q000032:analysis; D001483:Base Sequence; D002681:China; D004251:DNA Transposable Elements; D018744:DNA, Plant / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D018506:Gene Expression Regulation, Plant; D006239:Haplotypes; D001467:Hordeum / Q000737:chemistry* / Q000145:classification / Q000235:genetics*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013213:Starch / Q000737:chemistry*; D013214:Starch Synthase / Q000235:genetics* / Q000378:metabolism
chemical_list: D004251:DNA Transposable Elements; D018744:DNA, Plant; D010940:Plant Proteins; D012333:RNA, Messenger; C060756:waxy protein, plant; D013213:Starch; D000688:Amylose; C434607:granule-bound starch synthase I; D013214:Starch Synthase
keywords: GBSS I; Qinghai-Tibet plateau; Waxy; amylose; hull-less barley; starch properties