Current research progresses of amino acids uptake, transport and their biological roles in higher plants

Amino acids represent not only essential substrates for protein biosynthesis but also participate in nitrogenmetabolic pathways as well as regulatory processes of carbonnitrogen balance in plants. In the past years, understanding of mechanisms of uptake/transport of the amino acids and their biological roles has been paid a particularly increasing attention and thus become one of the most interested research areas in plant biology. More recently, certain publications have indicated that some amino acids could also act as signal molecules playing vital roles in plant growth. In this article, we have intensively reviewed and summarized recent progresses on molecular and physiological mechanisms of the uptake and transport of the amino acids as well as their crucial functions in plant growth and development (e.g. growth regulation, adaptive response to some abiotic stresses). Hopefully, our review will provide overall, updated and valuable information to researchers interested in plant amino acid biology, favoring deeper exploration and appreciation of potential biological roles of amino acidnutrition in higher plants.