芒是麦类作物穗部器官的重要组成部分,在提高籽粒产量、促进种子传播和防御虫害等方面具有重要作用.大麦具有丰富的芒型突变体,加之其二倍体的特性,成为麦类作物芒器官形态建成研究的理想作物.本研究报道了一个大麦芒型突变体材料calcaroides,表现为外稃顶端或是稃芒基部异形凸起,形成呈钩状不完全花器结构,属基部钩芒类型.突变体芒较短并伴随抽穗期推迟,株高、穗长和穗粒数显著降低等表型.遗传分析表明,突变体的芒型突变性状受单隐性基因cal-d控制.前期利用cal-d导入系BW106 × Bowman的F2群体,结合简化基因组测序(GBS,genotyping by sequencing)分析,将cal-d基因初步定位于3H染色体.进一步利用来自F2的杂合单株,包括13000株单株的F2∶3群体进行精细定位,最终将cal-d基因定位于3H染色体153～329Mb区间的近着丝粒区域.通过转录组混池测序分析结合大麦基因组和表达谱资源数据库,初步筛选了 9个候选基因.本研究结果为大麦芒型突变基因cal-d的克隆与功能验证奠定了基础,对于解析麦类作物芒的遗传发育机制具有重要的意义.
Genetic Mapping of an Awn Mutant Gene cal-d in Barley
Awn is an important part of spikes in crops such as wheat and barley,and plays a crucial role in improving grain yield,seed dispersal,and resistance to pests.Several awn mutants have been reported in barley,and its diploid characteristics make it an ideal genetic model for the morphological formation of awns in Triticeae crops.This study reported the genetic mapping of the gene cal-d of barley calcaroides awn-type mutant.The mutant belonged to base-hooked awn with a hooked-like structure between the top of lemma and the base of awn,and displayed a reduction significantly in plant height,spike and awn length,grain number per spike,and the delayed heading date.Genetic segregation analysis revealed that the trait of cal-d was controlled by a recessive gene.Firstly,the cal-d gene was preliminarily mapped to chromosome 3H,using the cal-d introgression line derived from a cross between BW106 and Bowman to combine the F2 population through genotyping by sequencing(GBS).With genotyping a total of 13,000 F2∶3 plants derived from F2 heterozygous plants to fine-map the gene,cal-d was delimited ultimately between 153-329 Mb,where the meager recombination rate was observed.Nine candidate genes were identified by transcriptome sequencing analysis in combination with the barley genome and expression profile resource database.Collectively,the results lay the foundation for the cloning and functional verification of the cal-d gene in barley mutant,and have important significance for analyzing the function of awn in Triticeae crops.
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