Book excerpt: Non-staple crops (sometimes known as underutilized, semidomesticated, orphan and/or forgotten crops) usually refer to under-researched grain and legume compared to staple crops, such as sweetpotato, buckwheat, millet, barley, pea, mung beans, and adzuki beans, which contain unique and beneficial nutrients that staple crops do not have. Combining them with staple foods is an important guarantee for a nutrition-balanced diet. With the deepening of research, the current research on non-staple crops has gradually started to create a wide range of materials, identify varieties and quality, improve yield, respond to environmental conditions and regulate growth and development. Therefore, it is an important research objective to improve the important agronomic traits of non-staple crops, including anthocyanins in sweetpotato, rutin in buckwheat, vitamins in millet, β-glucan in barley, etc. through both cultivation and molecular breeding methods and to create new germplasm resources with high yield and abundant nutrients. Recently, notable successes have been made using genomic-related approaches to uncover the genes responsible for important phenotypes in non-staple crops. The genetic basis of metabolomic divergence and domestication has been revealed in buckwheat, and the QTLs for controlling agronomic traits such as flesh color of sweetpotato have been obtained, however the function of related genes still needs further investigation. In addition, biotic and abiotic stresses in extreme climatic conditions change the yield and quality of crops by affecting the growth and development of crops and important metabolic regulation processes. Non-staple crops are often climate-resilient and grown in marginal regions with low-input conditions, including examples for tolerance of drought stress in cowpea and buckwheat, tolerance of heat in cassava and tolerance of barren in sweetpotato. Investigating the mechanism of their environmental adaptability would provide new insights for breeding of not only non-staple crops but also staple crops that are limited in the tolerance of a changing climate to ensure future food security. It is of great theoretical significance and practical application value to study the molecular regulatory network of non-staple crops under these stress conditions. • Using cultivation measures, plant growth regulators, fertilizers, and other methods to improve the environmental stress resistance and important agronomic traits in non-staple crops. • Revealing molecular mechanisms and regulatory network under all kinds of environmental stresses in non-major crops and improving stress tolerance through genetic engineering. • Identifying key regulatory genes of important agronomic traits in non- staple crops and improving molecular breeding methods.