ASR1 transcription factor and its role in metabolism.

Asr1 (ABA, stress, ripening) is a plant gene widely distributed in many species which was discovered by differential induction levels in tomato plants subjected to drought stress conditions. ASR1 also regulates the expression of a hexose transporter in grape and is involved in sugar and amino acid accumulation in some species like maize and potato. The control that ASR1 exerts on hexose transport is interesting from a biotechnological perspective because both sugar partitioning and content in specific organs affect the yield and the quality of many agronomically important crops. ASR1 affect plant metabolism by its dual activity as a transcription factor and as a chaperone-like protein. In this paper, we review possible mechanisms by which ASR1 affects metabolism, the differences observed among tissues and species, and the possible physiological implications of its role in metabolism.