ABA Receptor

When plants are challenged by various abiotic and biotic stresses, the endogenous ABA content increases and then exquisitely initiates some cellular signaling network to switch on adaptive responses and to regulate numerous developmental processes. ABA binds to PYR/PYL/RCAR (PYLs) and then the binary complex physically interacts with PP2Cs. The PYLs-PP2Cs heterodimer precludes substrate SnRK2s binding to PP2Cs, and thus stimulates SnRK2s kinase activity, which was formerly inhibited by PP2Cs. So far, 14 members of PYLs, six to nine group-A PP2Cs, three subclass III SnRK2s and four to nine group-A bZIP TFs are involved in the core ABA signaling pathway. There are 14 PYLs family members, named PYR1 and PYL1-PYL13 in Arabidopsis, that belong to the START superfamily. To date, the crystal structures of PYR1, PYL1, PYL2, PYL3, PYL5, PYL9, PYL10, and PYL13 have been reported. PYLs-mediated ABA signaling could play a crucial role in favoring stress adaptation and growth development for plants^[1].