title: Characterization of shrunken endosperm mutants in barley.
abstract: Despite numerous studies on shrunken endosperm mutants caused by either maternal tissues (seg) or kernel per se (sex) in barley, the molecular mechanism for all of the eight seg mutants (seg1-seg8) and some sex mutants is yet to be uncovered. In this study, we determined the amylose content, characterized granule-binding proteins, analyzed the expression of key genes involved in starch synthesis, and examined starch granule structure of both normal (Bowman and Morex) and shrunken endosperm (seg1, seg3, seg4a, seg4b, seg5, seg6, seg7, and sex1) barley accessions. Our results showed that amylose contents of shrunken endosperm mutants ranged from 8.9% (seg4a) to 25.8% (seg1). SDS-PAGE analysis revealed that 87 kDa proteins corresponding to the starch branching enzyme II (SBEII) and starch synthase II (SSII) were not present in seg1, seg3, seg6, and seg7 mutants. Real-time quantitative PCR (RT-qPCR) analysis indicated that waxy expression levels of seg1, seg3, seg6, and seg7 mutants decreased in varying degrees to lower levels until 27 days after anthesis (DAA) after reaching the peak at 15-21 DAA, which differed from the pattern of normal barley accessions. Further characterization of waxy alleles revealed 7 non-synonymous single nucleotide polymorphisms (SNPs) in the coding sequences and 16 SNPs and 8 indels in the promoter sequences of the mutants. Results from starch granule by scanning electron microscopy (SEM) indicated that, in comparison with normal barley accessions, seg4a, seg4b, and sex1 had fewer starch granules per grain; seg3 and seg6 had less small B-type granules; some large A-type granules in seg7 had a hollow surface. These results improve our understanding about effects of seg and sex mutants on starch biosynthesis and granule structure during endosperm development and provide information for identification of key genes responsible for these shrunken endosperm mutants.
authors: Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
authors: Jian
authors: J
authors: Ma
authors: Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
authors: Qian-Tao
authors: QT
authors: Jiang
authors: Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
authors: Long
authors: L
authors: Wei
authors: Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
authors: Ji-Rui
authors: JR
authors: Wang
authors: Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
authors: Guo-Yue
authors: GY
authors: Chen
authors: Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
authors: Ya-Xi
authors: YX
authors: Liu
authors: Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
authors: Wei
authors: W
authors: Li
authors: Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
authors: Yu-Ming
authors: YM
authors: Wei
authors: CSIRO Plant Industry, 306 Carmody Road, St Lucia, QLD 4067, Australia.
authors: Chunji
authors: C
authors: Liu
authors: Key Laboratory of Southwestern Crop Germplasm Utilization, Ministry of Agriculture, Sichuan Agricultural University, Ya'an, Sichuan 625014, China. Electronic address: ylzheng@sicau.edu.cn.
authors: You-Liang
authors: YL
authors: Zheng
mesh_terms: D015061:1,4-alpha-Glucan Branching Enzyme / Q000172:deficiency / Q000235:genetics; D000688:Amylose / Q000032:analysis*; D056625:Endosperm / Q000166:cytology / Q000235:genetics*; D020869:Gene Expression Profiling; D001467:Hordeum / Q000235:genetics*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D013214:Starch Synthase / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics
chemical_list: D010940:Plant Proteins; C060756:waxy protein, plant; D000688:Amylose; C111377:starch synthase II; D015061:1,4-alpha-Glucan Branching Enzyme; C112590:starch-branching enzyme II; D013214:Starch Synthase
keywords: Real-time quantitative PCR; Seg; Sex; Starch granule structure