青稞主效休眠基因单倍型分布及利用

Distribution and Application of Haplotypes of Major Dormancy Genes in Hulless Barley

穗发芽严重降低谷物的产量和品质,种子休眠与穗发芽高度相关。为了解中国青稞品种休眠特性及其主效休眠基因AlaAT和MKK3的单倍型分布,以143份地方品种和42份育成品种(系)为材料,分别种植在四川雅安、什邡和西藏拉萨,进行大田种子休眠性鉴定;选择休眠性极端材料,分别利用2对引物对含有目标休眠基因功能性SNP的片段进行扩增、测序,并用于AlaAT和MKK3基因特异性KASP标记开发与供试材料的单倍型分析。结果表明,3个种植点,地方品种的发芽指数(GI)均高于育成品种(系),但差异不显著;四川2个种植点间GI值差异不显著,但显著高于西藏种植点,说明青稞品种(系)普遍休眠性弱,高原气候条件显著促进种子休眠。KASP标记检测发现,AlaAT和MKK3的强优势单倍型均为弱休眠单倍型(频率>80%),供试材料中有4种单倍型组合,分别为AlaAT-ND+MKK3-ND、AlaAT-ND+MKK3-D、AlaAT-D+MKK3-ND和AlaAT-D+MKK3-D,频率分别为80.0%、12.4%、6.0%和1.6%,其GI值随强休眠单倍型数量增加而降低;3个环境下,含有组合AlaAT-D+MKK3-D的GI值最低,说明休眠基因具有加性效应,聚合优良单倍型的品种(系)具有稳定的休眠特性。青稞生产和育种应根据种植区域和用途选择与利用上述主效休眠基因单倍型。

Pre-harvest sprouting(PHS)severely causes a great loss of grain yield and quality.Seed dormancy is highly related to PHS.To reveal seed dormancy and gene haplotype of hulless barely in terms of major dormancy genes AlaAT and MKK3,143 landraces and 42 cultivars(lines)grown in three planting sites,including Yaan and Shifang of Sichuan,and Lhasa of Tibet,were used for seed dormancy investigation.Accessions with extreme dormancy were selected for validating the causal SNP in AlaAT and MKK3 using two pairs of primers and developing gene specific markers for haplotype analysis.The results showed that germination index(GI)of cultivars(lines)is higher than that of landraces in all planting sites but without significant difference.The mean GI in Sichuan is significantly higher than that in Tibet whereas there is no significant difference between the two sites of Sichuan,indicating that hulless barley generally had weak dormancy and highland climate likely promoted seed dormancy.KASP assay showed the haplotype of AlaAT and MKK3 related to weak dormancy were absolutely predominant in tested panels,with the frequency more than 80%.There are four haplotype combinations of the target genes,AlaAT-ND+MKK3-ND,AlaAT-ND+MKK3-D,AlaAT-D+MKK3-ND and AlaAT-D+MKK3-D,with afrequency of 80.0%,12.4%,6.0%and 1.6%,respectively.GI decreased with increased number of prior haplotype,but the GI of AlaAT-D+MKK3-D group is the lowest in all sites,indicating that additive effect existed among dormancy genes and stable dormancy in genotypes with a few dormant haplotypes.The prior haplotype of the major dormancy genes above should be selected and applied in hulless barley production and breeding program,according to growing area and grain end use.