A Step-by-step Protocol for Crossing and Marker-Assisted Breeding of Asian and African Rice Varieties.

Improving desirable traits of popular rice varieties is of particular importance for small-scale food producers. Breeding is considered the most ecological and economic approach to improve yield, especially in the context of pest and pathogen-resistant varieties development. Being able to cross rice lines is also a critical step when using current transgene-based genome editing technologies, e.g., to remove transgenes. Moreover, rice breeders have developed accelerated breeding methods, including marker-assisted backcross breeding (MABB) to develop novel rice varieties with in-built resistance to biotic and abiotic stressors, grain, and nutritional quality. MABB is a highly efficient and cost-effective approach in accelerating the improvement of recipient variety by introgressing desirable traits, especially from landrace cultivars and wild rice accessions. Here, we provide a detailed protocol including video instructions for rice crossing and MABB to introgress target trait(s) of interest into the elite rice line. Further, we also highlight tips and tricks to be considered for a successful crossing and MABB. Key features • This protocol provides detailed information on techniques for crossing rice varieties and for breeding rice varieties with new traits • The protocol includes instructions for making rice crosses as well as MABB • The protocol provides beginners with detailed instructions including troubleshooting guides Graphical overview Illustration of crosses of rice lines and marker-assisted backcross breeding (created with BioRender.com).