菊花扦插生根能力的动态QTL定位与功能型分子标记开发

Chrysanthemum is one of the ten famous traditional flowers in China and of the four leading cut-flowers in the world, thus possessing great ornamental and commercial values. Owing to the genetic differences, the rooting ability of cuttings varies enormously between different chrysanthemum cultivars. Fast and high-quality rooting abilities of cuttings are critically important for efficient chrysanthemum seed/seedling industry and closely associated with the growth and development in field production. Thus, a well understanding of the genetic basis of cuttings’ rooting-related traits is of vital importance for future breeding and improvement for rooting ability in chrysanthemum. In this proposal, we first investigate the genetic variability of cuttings’ rooting ability in both cultivars and hybrid progenies. Then, we construct high-density genetic linkage maps for chrysanthemum cultivars with different rooting ability, and uncover the dynamic QTL underlying rooting ability at different cuttage stage via conditional and unconditional QTL analysis, and reveal the interactive espitasis between QTLs and QTL with environments/years. Thirdly, we will achieve consistent QTLs that express stable across different cuttage stages and environments/years, and predict the elite SNP alleles and candidate genes that contribute to cuttings’ rooting ability. Finally, some functional molecular markers, say CAPS or dCAPS will be developed for cuttings’ rooting ability and be validated in both cultivar and hybrid populations with contrasting rooting ability. The findings will uncover the dynamic genetic determinism and obtain some functional molecular markers for cutting’s rooting ability, and will be of theoretical and practical significance for future genetic improvement and molecular marker assistant selecting breeding for the target traits in chrysanthemum.

菊花是我国十大传统名花和世界四大切花之一，观赏和经济价值高。由于遗传特性不同，菊花品种扦插生根难易程度差异较大。快速扦插生根能力和良好生根质量不仅是菊花种（苗）业高效健康发展的关键，而且与菊花后期生长发育和抗/耐性密切相关。因此，明确菊花扦插生根过程的遗传基础对菊花扦插生根能力的遗传改良至关重要。本项目拟利用品种资源和杂交群体研究菊花扦插生根能力的遗传变异规律；利用基于高通量测序的SNP等分子标记构建菊花高密度遗传图，通过非条件与条件QTL分析揭示菊花扦插生根能力的动态QTL表达特性，研究QTL间以及QTL与环境间的互作上位性遗传机制，挖掘“一致性”主效QTL；并根据主效QTL区域优异SNP位点和候选基因开发CAPS或dCAPS等功能型分子标记。项目实施将阐明菊花扦插生根能力的动态遗传机制，获得相关功能型分子标记，对后期目标性状的遗传改良和分子标记辅助选择育种具有重要的理论和实践指导意义。

菊花是我国十大传统名花和世界四大切花之一，观赏和经济价值稿。由于遗传特性不同，菊花品种扦插生根难易程度差异较大。快速扦插生根能力和良好的生根质量不仅是菊花种（苗）业高效健康发展的关键，而且与菊花后期生长发育和抗耐性密切相关。因此，明确菊花扦插生根过程的遗传机制对目标性状的遗传改良至关重要。本项目调查了菊花自然群体和F1群体在不同生长时期扦插生根能力的遗传变异情况，发现菊花自然群体9个扦插生根相关性状存在着较为广泛的变异，变异系数为15.87%–66.68%；切花小菊‘南农雪峰’בMonalisa’ F1群体不同时期的扦插生根能力相关性状分离广泛且超亲分离现象明显。主基因+多基因混合遗传分析结果表明，不同扦插生根性状在不同生长时期的主基因遗传效应存在一定差异，遗传机制较为复杂。基于高通量SNPs和“双-假测交”策略构建了菊花高密度遗传图谱，共包含27条连锁群、11 941个bin标记，图谱总长度为2967.76 cM，平均标记间距为0.26 cM。通过动态QTL分析，在不同生长时期共检测到140个QTL和6对上位性QTL与菊花扦插生根能力显著相关，单个QTL贡献率为0.04% – 9.78%，上位性QTL表型变异解释率介于0.13% – 3.28%之间，并根据QTL区域核苷酸序列的生物信息学分析，预测到9个主要候选基因。另外，还利用多个模型对四个主要生根相关性状进行关联分析，共检测到62个显著等位变异位点与生根性状显著相关，其中27个优异等位变异位点（SNPs），并根据显著SNPs在基因组上下游区间进行基因挖掘与注释，共筛选得到425个候选基因。本项目研究结果对菊花扦插生根能力的遗传改良具有重要理论和实践指导意义。