Research Revealed Establishment of the Xinjiang Wild Apple Regeneration and CRISPR/Cas9 Gene Editing System

Wild apple (Malus sieversii) is a precious Tertiary relic plant in Xinjiang, and the ancestor of the world cultivated apple (Malus domestica), with rich resistance gene resources value. In the past two decades, due to global change and human interference influence, the outbreak of plant diseases and insect pest, including Agrilus mali and Valsa canker, had greatly caused wild apple population area shrink, and the species has been listed as the national secondary endangered protection plant. The protection and breeding of wild apples and utilization of resistance gene resources are imminent.

Because of the self-incompatibility and perennial woody plant characters of wild apples, conventional breeding methods are difficult to meet the needs of germplasm innovation. CRISPR/Cas9 technology has been successfully used in a variety of plants, and had been proved to be useful tool in woody plants. However, using CRISPR/Cas9 technology to create wild apple new germplasm and research its gene function is almost zero.

Research team of Prof. Zhang daoyuan from State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences has created the tissue culture system of wild apple to shorten the regeneration system to 2-3 months.

This method can be used for mass propagation of cloned seedlings of wild apple. The research results titled "An efficient in vitro regeneration system from different wild apple (Malus sieversii) explants” were published in BMC Plant Methods.

Subsequently, on the basis of successfully obtaining the optimal wild apple regeneration system, researchers applied the gene editing tool CRISPR/Cas9 system to this species for the first time, and achieved good editing results. The research results titled " Application of CRISPR/Cas9 Technology in Wild Apple (Malus sieverii) for gene editing” were published in BMC Plant Methods.

The establishment of regeneration and genetic transformation system of wild apple will lay a foundation for the study of gene function and the creation of new germplasm. At the same time, the successful application of CRISPR/Cas9 technology will also accelerate the modern molecular breeding process of wild apple.

Article link: https://plantmethods.biomedcentral.com/articles/10.1186/s13007-020-00599-0 

Article link: https://plantmethods.biomedcentral.com/articles/10.1186/s13007-021-00769-8 

Fig. 1 Callus regeneration system of Xinjiang wild apple

Fig. 2 CRISPR/Cas9 vector construction process, Sanger sequencing examples of mutations in different calli and positive calli