Antisense transcription represses seed dormancy QTL to regulate drought tolerance.

Plants have developed multiple strategies to sense the external environment and to adapt growth accordingly. () is a major quantitative trait locus (QTL) for seed dormancy strength in that is reported to be expressed exclusively in seeds. is extensively regulated, with an antisense transcript () suppressing its expression in seeds. Here, we show that shows high levels in mature plants where it suppresses expression under standard growth conditions. Suppression is released by shutting down antisense transcription, which is induced by the plant hormone abscisic acid (ABA) and drought. Loss of results in constitutive high-level expression, conferring increased drought tolerance, while inactivation of causes enhanced drought sensitivity. The unexpected role of in environmental adaptation of mature plants is separate from its function in seed dormancy regulation. The requirement of to respond to ABA and drought demonstrates that antisense transcription is important for sensing and responding to environmental changes in plants.