The Roles of MADS-Box Genes from Root Growth to Maturity in Arabidopsis and Rice

Rice (Oryza sativa L.) and Arabidopsis thaliana (L.) life cycles involve several major phase changes, throughout which MADS-box genes have a variety of functions. MADS-box genes are well recognized for their functions in floral induction and development, and some have multiple functions in apparently unrelated developmental stages. For example, in Arabidopsis, AGL15 and AGL6 play roles in both vegetative development and floral transition. Similarly, in rice, OsMADS1 is involved in flowering time and seed development, and OsMADS26 is expressed not only in the roots, but also in the leaves, shoots, panicles, and seeds. The roles of other MADS-box genes responsible for the regulation of specific traits in both rice and Arabidopsis are also discussed. Several are key components of gene regulatory networks involved in root development under diverse environmental factors such as drought, heat, and salt stress, and are also involved in the shift from vegetative to flowering growth in response to seasonal changes in environmental conditions. Thus, we argue that MADS-box genes are critical elements of gene regulation that underpin diverse gene expression profiles, each of which is linked to a unique developmental stage that occurs during root development and the shift from vegetative to reproductive growth.