芸薹属含B基因组野生植物及其近缘野芥在中国的可能分布、评价和保护研究

Oilseed rape is the main oil crop in China and its cultivation area is the largest in the world. Many useful genes located in B-genome of Brassica that are important for crop improvement, although the natural distribution of wild Brassicas containing B-genome was remained unconfirmed by scientific evidences. This is important for supporting the theory of origination of B-genome containing species in China. The S-genome is homogenous to B-genome, which is assumed as the progenitor of B-genome, and can also express excellent agronomy traits that can be used in crop breeding. However, these plant resources frequently live near to or on farmlands and are liable to be affected by the human activities during agricultural cultivation and the growing of cultivated oilseed rape. The value of these plant genetic resources needs immediate understanding and protection before their extinction. Unfortunately, there is a lack of conservation efforts, to protect these wild genetic resources of the oilseed crops. This project aims to investigate on the distribution status of those B-genome containing wild Brassicas (i.e. B. juncea and B. nigra) and the closely related Sinapis arvensis and the effects posed on their growth and survival resulted from human cultivation and the Brassica crops. The wild collections will be evaluated by plant morphology, especially the seed coat microsculpturing, and ploidy levels by flow cytometry and identified by genomic specific markers. The species identification will be confirmed by hand-crossing with known species controls. The growth health and population dynamics will be compared between wild populations distributed in natural lands and those in or near to farmlands to evaluate the effects of cultivation activities. The sexual compatibility between those wild species and populations and cultivated oilseed rape will be studied to assess the possibility of gene flow and the following introgression from crops, which will probably contaminate the wild genetic resources and reduce their genetic integrity and further utilization in breeding. Based on the sexual compatibility, certain wild species and populations will be chosen to evaluate resulted genetic integrity by comparing between natural populations and the ones grown on farmland and neighbor sites. The potentially resistant populations to blackleg will be also screened by reported specific molecular markers to add value to the genetic resources. Control plants will be employed though this study. Based on the results of evaluation, conservation strategies, including both in situ and ex situ, will be proposed to better improve the conservation of wild Brassicas in China and the following utilization for current and future uses.

油菜是中国的主要油料作物，栽培面积居世界首位。芸薹属的B基因组携带了很多优良的抗性基因，能够促进油菜育种。与B基因组近缘的SS基因组野芥同样具有很多优良性状。这些物种资源一般都生长在农田附近，极易受到耕作及栽培油菜的影响，亟待了解和保护。本课题从调查中国褐芥、野芥和或黑芥的野生分布入手，结合种皮饰纹和基因组分子标记及有性杂交等手段鉴别物种，了解这些物种资源植物在中国的保有状况。结合生态学调查，比较自然分布种群和农田分布种群的生长状态和遗传多样性，评价耕作活动的影响。研究栽培油菜与不同物种和野生种群的有性杂交亲和度，评价发生栽培油菜基因渐渗的风险。在此基础上，选择较易发生基因渐渗的物种或种群，评价栽培油菜的基因渐渗对野生种群遗传多样性的可能影响。课题还计划以B基因组和S基因组特有的抗黑胫病特性为例，用分子标记鉴别相关的具有潜在抗性的野生种群，验证资源的价值。综合所有的结果，提出保护建议。

油菜是中国的主要油料作物，栽培面积居世界首位。芸薹属的B基因组携带了很多优良的抗性基因，能够促进油菜育种。与B基因组近缘的SS基因组野芥同样具有很多优良性状。这些物种资源一般都生长在农田附近，极易受到耕作及栽培油菜的影响，亟待了解和保护。本项目从调查中国褐芥、野芥和或黑芥的野生分布入手，结合实验室研究，利用分子生物学、地理信息系统、电镜技术以及辅助杂交手段取得以下成果：1）分析了芸苔属B基因组的野生种及其近缘野芥种皮纹饰特征，揭示了特定基因组类型的种皮纹饰特点，能够为区分B基因组的野生近缘种和S基因组的野生近缘种提供快速而准确的手段；2）利用分子标记和病原菌接种筛选了油菜野生近缘种中的黑胫病抗性资源，为进一步的资源利用工作奠定了基础，为抗性育种工作提供了依据；3）研究了芸薹属野生近缘种与栽培油菜的杂交亲合性，了解到各野生近缘种地理种群与栽培油菜的杂交亲合度，为基因流风险以及在杂交育种中的可能作用提供了理论基础；4）项目开展了全国栽培油菜与芸薹属野生近缘种基因流风险的评估，鉴定了基因流风险比较高的地区，提出了降低和避免基因流污染的应对策略。