荒漠草原上的旱生植物在漫长的适应严酷环境过程中，形成了独特的抗逆机制，揭示其分子基础并发掘所蕴含的丰富抗逆基因资源，对因长期在较优裕条件下栽培种植、抗逆性遗传潜力十分有限的优良牧草的遗传改良具有重要的理论及应用价值。我们前期研究表明，大量吸收积累K+、Na+、Cl-和发达的叶表皮角质层在多浆旱生植物霸王适应干旱、盐渍、高温等生境过程中发挥着重要作用，并筛选到一系列相关的逆境响应功能基因及转录因子。在此基础上，本项目拟采用转录组测序、RNA原位杂交、异源表达、CRISPR-Cas9等技术，进一步系统阐明霸王上述逆境适应过程中的重要功能基因及转录因子的作用机制；并将若干具有潜在应用价值的霸王关键抗逆基因转入重要牧草紫花苜蓿，创制一批抗逆、高产、优质的育种新材料。项目的实施，将有助于突破栽培牧草遗传改良中抗逆基因资源匮乏的瓶颈，为大幅度提高紫花苜蓿等优良牧草的抗逆性开辟新途径。

The xerophytes living in desert steppes have evolved specialized strategies to survive in harsh environments. Understanding the molecular mechanisms, including identifying key stress-resistance genes from xerophytes, is important for our fundamental knowledge of plant stress adaptation. It also allows for genetic improvement of fine forages, which have been cultivated under favourable farming regimes for a long period and thus possess very limited natural stress resistance. Our previous investigation has demonstrated that high accumulation of K+, Na+, Cl- ions and well-developed leaf cuticles allow the succulent xerophyte Zygophyllum xanthoxylum to successfully adapt to drought, saline, and high temperature conditions. In addition, we have identified a series of stress-responsive genes encoding functional proteins and transcription factors involved in above adaptation processes of Z. xanthoxylum. In this proposal, the functional mechanisms of these genes will be analyzed by combining molecular biological techniques, including transcriptome sequencing, RNA in situ hybridization, heterologous expression, and CRISPR-Cas9-mediated genome editing. The key stress-resistance genes from Z. xanthoxylum will then be chosen and transformed into important forage alfalfa (Medicago sativa L.) to generate a batch of novel breeding materials with enhanced stress resistance, high yield and good quality. This project will contribute to breaking the bottleneck of stress-resistance gene scarcity in genetic improvement of cultivated forages, and open a new avenue for significantly enhancing the stress resistance of fine forages, such as alfalfa.