Identification of quantitative trait loci controlling grain size and shape in the D genome of synthetic hexaploid wheat lines

Synthetic hexaploid wheat is an effective genetic resource for transferring agronomically important genes from Aegilops tauschii to common wheat. Wide variation in grain size and shape, one of the main targets for wheat breeding, has been observed among Ae. tauschii accessions. To identify the quantitative trait loci (QTLs) responsible for grain size and shape variation in the wheat D genome under a hexaploid genetic background, six parameters related to grain size and shape were measured using SmartGrain digital image software and QTL analysis was conducted using four F₂ mapping populations of wheat synthetic hexaploids. In total, 18 QTLs for the six parameters were found on five of the seven D-genome chromosomes. The identified QTLs significantly contributed to the variation in grain size and shape among the synthetic wheat lines, implying that the D-genome QTLs might be at least partly functional in hexaploid wheat. Thus, synthetic wheat lines with diverse D genomes from Ae. tauschii are useful resources for the identification of agronomically important loci that function in hexaploid wheat.     

人工合成异源六倍体小麦β-葡萄糖苷酶活性的变化

[目的]研究小麦多倍化初期β-葡萄糖苷酶活性的变化。[方法]以生长17d的人工合成异源六倍体小麦(第五代)及其父本粗山羊草、母本硬粒小麦的叶片为材料,采用pNPG法测定β-葡萄糖苷酶的活性,采用分光光度法测定可溶性蛋白含量,进而研究了六倍体小麦多倍化初期β-葡萄糖苷酶活性的变化。[结果]二倍体父本TQ27中β-葡萄糖苷酶的比活力略高于四倍体母本TTR04,但差异不显著。人工合成六倍体小麦AT5中β-葡萄糖苷酶的比活力最低,与其父本TQ27、母本TTR04中β-葡萄糖苷酶比活力差异显著。TQ27、TTR04和AT5中β-葡萄糖苷酶的平均比活力分别为62.36、64.66和24.15U/(μg.h)。[结论]异源多倍化初期六倍体小麦的β-葡萄糖苷酶活性较其双亲显著降低。     

利用SCoT标记分析花生栽培种×A. chacoensis 组合异源多倍化的早期基因组变化

【目的】研究花生属异源多倍化过程中基因组变化行为,揭示花生属多倍体进化的分子机制。【方法】采用SCoT标记对四倍体栽培种仲恺花4号和二倍体野生种A. chacoensis的种间杂种F1及早期多倍体世代（S0—S3）基因组变化时间、类型和频率进行分析。【结果】18条SCoT引物共扩增出126个位点, 其中多态性位点117个,多态性比率达92.86%,在供试材料中检测出了丰富的DNA多态性;与扩增出的109条亲本条带比较,F1—S3分别丢失亲本条带28、30、10、11和10条,其中,来自父本特异性条带为16、12、7、9和9条,各自新增条带9、3、10、14和8条,说明SCoT产物早在Fl即开始发生变化,变化类型包括亲本条带的丢失、跳跃式继承和新条带的产生,在丢失的亲本条带中以父本条带为主。【结论】ATG翻译起始位点及其侧翼区域在花生种间杂交异源多倍化早期迅速发生广泛而剧烈的变化,其生物学功能可能与多倍体的进化和稳定有关;SCoT标记作为一种简单、有效和实用的新型功能型分子标记技术,可以为花生属及其它物种多倍体进化中基因组遗传变化研究提供技术支持。     

Expression of morphological and flowering time variation through allopolyploidization: an empirical study with 27 wheat synthetics and their parental Aegilops tauschii accessions

It was recently shown that allopolyploidy brings novel epistatic interactions to genes belonging to different genomes. However, systematic studies of the phenotypic relationships between synthetic hexaploid wheats and their parental lines have not been conducted. In this study, 27 synthetic hexaploid wheats were produced by crossing the tetraploid wheat cultivar ‘Langdon’ with 27 accessions of Aegilops tauschii. Variations in 20 morphological and flowering traits were analysed in both the synthetic wheat lines and the parental Ae. tauschii accessions. The 20 traits exhibited large variations in the wheat lines. For many of the traits, the degree of variation in the parental accessions was reduced in the hexaploid derivatives. Principal component analysis of floret‐related traits divided the Ae. tauschii accessions into two subspecies, ssp. tauschii and ssp. strangulata, but this parental pattern of subspecific division was not detectable in the hexaploids. Our results suggest that the ‘Langdon’ genome may have an alleviating effect on the expression of D‐genome‐derived variations in derived synthetics.