Cloning And Functional Analysis Of Drought Stress Induced Gene ZmMADS4 In Maize (Zea MaysL.)

The MADS-box gene family is a transcription factor family which sequences are specific. It iswidely existed in human, animal and plants. MADS-box genes play diverse roles in plant development.According to the phylogenetic analysis the MADS-box gene families in Arabidopsis are divided into fivegroups named Met, Mβ, Mγ, Mδand MIKC. And the members of MIKC have a typical structure ofMADS domain, I domain, k domain and C terminal.In our previous studies, we found a MADS-box gene induced by drought stress in maize, namedZmMADS4. To better understand the role of ZmMADS4 in stress-responsive pathway. The RACEdegenerate primer was designed according to the conserved MADS-box domains of monocotyledon twobases before the initiation codon. ZmMADS4 was cloned by 3'-RACE with degenerate primer andUPM.The cDNA fragment including the 3'UTR (206bp) and the coding region (735bp). ZmMADS4 waspredicted to encode a protein of 244 amino acids with an estimated molecular mass of 27.9KDa.Database searches revealed that the deduced amino acid sequence of ZmMADS4 has a typical MADSdomain. This indicated that ZmMADS4 is a member of MADS-box family. The result of subcellularlocalization revealed that ZmMADS4 was localized to the nuclear.At the same time, six additional ZmMADS genes, named ZmMADS5, ZmMADS6, ZmMADS7,ZmMADS8, ZmMADS9 and ZmMADS10 were obtained. Analysis of all seven ZmMADS genes and sixMADS genes of Arabidopsis by Clustalw revealed that they had high conserved MADS domain.Northern blot analysis revealed that the expression of ZmMADS4 was induced in maizeunpollination ears and silks by drought stress. Results of RT-PCR indicated that ZmMADS6 has the samefunction as ZmMADS4. The two genes were induced in maize seedings by drought, salt, exogenous ABAand low temperature (4℃). ZmMADS10 was induced in maize seedings by drought, exogenous ABA andlow temperature. ZmMADS9 was only induced by water stress. The other four genes ZmMADS5,ZmMADS7 and ZmMADS8 were not detected in leaves under stress.Arabidopsis plants with double-stranded ZmMADS4 RNA were generated through transformationvia Agrobacterium. Transgenic plants showed a higher germination rate on mannitol or sodium chloridecontaining medium than wild type plants. The contents of proline and chlorophyll of transgenic plantswere higher than that of wild type under drought stress. All results indicate that ZmMADS4 has animportant role in response to abiotic stress.