Scientists Trace Evolution of Abscisic Acid

An international research team from Germany, Australia, and the USA has studied the evolution of the phytohormone abscisic acid (ABA). The study focused on the hormone's role in water balance and pore regulation. ABA is key for drought tolerance in plants, for when plants are water-stressed, ABA closes the stomates to prevent wilting. However, the role of ABA in ferns and other lycophytes remains unclear.

The research team has determined that ABA plays a key role in determining the sex of ferns, using a mechanism that was co-opted by flowering plants to tolerate desiccation. They found the homologous fern gene responsible for ABA signaling. They also found that the proteins produced when the ABA signaling pathway is turned on do not interact with proteins that would open and close stomates. They realized that regulating stomate closing by ABA was new to angiosperms, which evolved from ferns about 150 million years ago. They also found that ABA promotes femaleness in plants, and is linked to spore dormancy in ferns.

For more details, read the news articles at Purdue University and University of Würzburg websites.