Transcription factors of the MADS family in plants: relationship with domestication traits and prospects for breeding (review)

The traits of domestication, which are subdivided into three groups (productivity, adaptability, and reproduction) and together make up a domesticated syndrome that brings together taxonomically distant domesticated forms, remain economically significant in modern cultivated crops as well. A significant part of the genes that control domestication traits in plants are represented by the genes of transcription factors, in particular, those belonging to the MADS-domain family. MADS-domain proteins are key regulators of almost all aspects of plant reproductive development, including the determination of the flowering time, the inflorescence structure, the flower organ identity, the development of roots, fruits, and seeds, as well as the adaptive and stress response to adverse environmental conditions. The presented review describes the possible involvement of MADS-box genes in plant domestication and breeding. We discuss the role of MADS-box genes in the regulation of vernalization (plant response to prolonged cold treatment), bud physiological dormancy, inflorescence and flower structure, plant fertility and fruit qualitative traits (ripening characteristics, synthesis of carotenoids and anthocyanins, the number of seeds, fruit shuttering, fruit shelf life), as well as plant stress response (salinity, drought, temperature changes). The phenomenon of MADS-box gene functional pleiotropy and redundancy (due to the existence of paralogs) is considered. It has been supposed that MADS-box genes high structural and functional conservatism may indicate their high potential as tools for predictable fine tuning of crop phenotypes by combining (including dose-dependent) different alleles and paralogs of MADS-box genes. Another possible method is the separation of the pleiotropic functions of the MADS-box gene by introducing mutations in its coding or cis -regulatory sequence to alter specific protein-protein or protein-DNA interactions, as well as the pattern and/or level of expression, including in response to various external and internal signals. It is concluded that fundamental and applied studies of MADS-box genes in various plant species (both wild and cultivated) will not only lead to a deeper understanding of the evolution and development of modern plants, but will also greatly contribute to the improvement of crops, including using CRISPR/Cas and other modern technologies.