Cloning And Functional Identification Of The Abscisic Acid Receptor Candidate Gene In Maize

Abscisic acid is an important endogenous plant hormone involved in the regulation of a variety of physiological processes such as defoliation, seed development and dormancy, stomatal opening and closing,especially play an important role in response to biotic and abiotic stress. Abscisic acid The signal transduction abscisic acid-mediated is a key link in the plant response to stress. Abscisic acid signal transduction is initiated with the perception of abscisic acid, the molecule for signal perception is called a abscisic acid "receptor" and is regarded as one of the most important components for deciphering a complex network of signal transduction pathways. The identification of the receptor protein is critical in the study of abscisic acid signal transduction. Group A protein phosphatases type2C (PP2Cs) are negative regulators of the abscisic acid signaling from the initial part in Arabidopsis,and a class of PYR(Pyrabactin Resistance1)/PYL(PYR1-Like)protein were identified as abscisic acid receptors by two independent research group published in Science in2009. The combination of PYL and abscisic acid causes conformational changes which brought in an abscisic acid-dependent inhibition on the downstream PP2Cs for preventing substrate proteins into the PP2C activity center, and then activated phosphokinase activity of SnRK2s, consequently meidated a series of ABA-dependent regulation to stress response. Cloned and characterized the PYLs can promote the study of abscisic acid signal transduction and the resilience research such as drought tolerance in maize.In this study, we searched the maize inbred line’B73’genome with the Arabidopsis peptide sequences of14PYL as probe. after the prediction and analysis with bioinformatics softwares we got12complete cDNA sequence of PYLs in maize, named as ZmPYL1-12. Then we cloned the open reading frame of12ZmPYL and11known ZmPP2C, afterwards we constructed23expression vectors for yeast two-hybrid system to transform into yeast strains AH109. We examined whether there is an interaction between12ZmPYLs and11PP2Cs in vitro. Only13of132pairs presenced interactions, this may be the complexity of the maize genome duplication and diversity. The interaction pairs are ZmPYL4/ZmP P2C3, ZmPYL5/ZmP P2Ca, ZmPYL5/ZmP P2C3, ZmPYL5/ZmPP2C4, ZmPYL5/ZmPP2C7, ZmPYL5/ZmP P2C9, ZmPYL5/ZmPP2C10, ZmPYL7/ZmP P2C3, ZmPYL7/ZmP P2C9, ZmPYL8/ZmP P2Ca, ZmPYL8/ZmPP2C3, ZmPYL7/ZmP P2C9. The PYLs that could occur an interaction with the PP2Cs were ZmPYL4,5,7,8which belong to the PYL subfamily Ⅱ. But all of the13pairs protein interactions have no realationship with the existence of ABA in our study. Our result is inconsistent with previous reports on Arabidopsis. For that reason, the maize abscisic acid receptor still need further experiments to veritication.