China scientists discovered a new chemical helping plants fight drought

China scientists discovered a new chemical that mimicks ABA, a key phytohormone that helps plants cope with drought and other environmental stresses.

The phytohormone abscisic acid (ABA) plays a critical role in plants to combat abiotic stresses, such as drought, salinity and extreme temperatures. Data from the World Bank shows that drought stress accounts for more than half of global crop losses and the situation is getting worse with climate changes presumably caused by global warming. ABA can be used in agriculture to help different crops survive severe drought. However, the use of ABA in agricultural applications has been hampered by its chemical instability and expensive cost of industrial production of ABA.
 
A collaborative research led by Dr. Jian-Kang Zhu of the Shanghai Center for Plant Stress Biology, CAS, has discovered a chemical alternative, ABA Mimics 1 (AM1), that can mimic ABA function in enhancing drought resistance in plants. The findings were published in the latest issue of Cell Research (2013, Jul 10.1038/cr.2013.95).  AM1 is a sulfonamide-based structural analog of ABA and pyrabactin; it was shown to be effective in boosting drought resistance in plants with similar characteristics to that induced by ABA. AM1 can mimic the function of ABA through binding to multiple members of the PYR/PYL family of ABA receptors, thereby inhibiting the activity of protein phosphatase 2Cs (PP2Cs) and activating the downstream ABA signaling pathway. The structural analyses of AM1 in complex with PYL2-HAB1 revealed an AM1-ligand mediated gate-latch-lock interacting network, a structural feature that is conserved in the ABA-bound receptor/PP2C complex. In vivo assays further demonstrated that AM1 is capable of activating the expression of ABA-responsive genes, preventing transpirational water loss from leaves and dramatically enhancing drought resistance in plants. Furthermore, AM1 is easily synthesized and more resistant to photolysis than ABA, indicating that AM1 has a great potential to become an ABA replacement in agricultural applications for stabilizing crop yield and conserve previous water resource under environmental stresses.