钙网蛋白Calreticulin 2介导大白菜抗干烧心的分子机制研究

Tipburn is one of the irreversible physiological disorders that cause large economic losses in the production of Chinese cabbage. At present, main varieties of Chinese cabbage show no resistance to the disease. Moreover, environmental factors such as soil deterioration, abnormal weather and improper management of water and fertilizer increase the incidence of tipburn. Due to poor accuracy of the evaluation system as well as unclear genetic control, tipburn has been a terribly difficult problem in Chinese cabbage breeding. Previous studies demonstrated that calcium (Ca2+) deficiency is the main cause of tipburn in Chinese cabbage. We pioneered the research to carry out large-scale disease resistance evaluation and identification of tipburn in a set of 302 germplasms and then mapped a candidate gene BrCRT2, conferring tipburn tolerance, by using genome-wide association analysis (GWAS), QTL mapping and Bulked Segregant Analysis (BSA). The results from transcript analysis, molecular marker validation and Arabidopsis transgenic showed that BrCRT2 involves in the physiological processes of low calcium stress in plants. In this study, haplotype analysis and transgenic validation (Chinese cabbage) will be firstly conducted to confirm the function of BrCRT2 in tipburn pathogenesis. Then, the function of BrCRT2 on the Ca2+ homeostasis between cytoplasm and endoplasmic reticulum will be investigated by Ca2+ tracer. Finally, the expression regulating factors and interacting protein of BrCRT2 will be identified to construct a molecular regulation network. The above results will provide a theoretical basis and a new gene source for molecular breeding of tipburn-tolerant varieties.

干烧心病是严重影响大白菜产量和质量的重要病害；而气候异常、土壤恶化和水肥管理不当等因素导致其防控难度极大。鉴定技术准确性差，抗性机制研究不足，使得抗病品种选育异常困难。研究显示缺钙是干烧心病发生的关键诱因。本课题组在国内率先建立了干烧心病鉴定标准化技术，基于GWAS、QTL定位和混池测序方法，获得了控制干烧心抗性的关键候选基因BrCRT2。表达分析、标记验证和拟南芥转基因结果显示BrCRT2参与低钙抗性反应。本项目拟通过单体型分析获得BrCRT2变异位点，开发功能基因分子标记；利用转基因验证BrCRT2参与白菜干烧心抗病过程；采用Ca2+示踪研究低钙胁迫下BrCRT2在调控Ca2+稳态平衡中的作用；鉴定BrCRT2的表达调控因子和互作蛋白，构建BrCRT2参与干烧心抗性的分子调控网络。研究结果对大白菜干烧心抗病分子机制的揭示和抗病分子育种具有重要意义。

干烧心病是严重影响大白菜产量和质量的重要病害；目前生产上的主栽品种均不具抗病性，而气候异常、土壤恶化和水肥管理不当等因素导致其防控难度极大。鉴定技术准确性差，抗性机制研究不足，使得抗病品种选育异常困难。研究显示缺钙是干烧心病发生的关键诱因。本课题组在国内率先建立了干烧心病鉴定标准化技术，基于GWAS、QTL定位和混池测序方法，获得了控制干烧心抗性的关键候选基因BrCRT2。表达分析、标记验证和拟南芥转基因结果显示BrCRT2参与低钙抗性反应。进一步，我们利用单体型分析获得了BrCRT2的功能变异位点，并开发了相应的功能基因分子标记；利用转基因验证BrCRT2参与白菜干烧心抗病过程已经用于育种。在BrCRT2作用的分子机理上，我们采用Ca2+示踪揭示低钙胁迫下BrCRT2在调控Ca2+稳态平衡中的作用，证明感病单体型的BrCRT2其钙离子持有能力降低。研究结果对大白菜干烧心抗病分子机制的揭示和抗病分子育种具有重要意义。此课题分子标记辅助选择育种的实施和成果的普及，将培育抗干烧心病白菜新品种，推进北京乃至我国白菜产业的可持续发展。