| 1 | Leucine zipper like structure in rice WRKY89 enhances its affinity for binding with W box elements显示文摘WRKY proteins are transcriptional regulators involved in plant responses to biotic and abiotic stresses, metabolisms, and developmental processes. In the present study, we isolated a WRKY cDNA, OsWRKY89 from a rice cDNA library. The deduced polypeptide contains 263 amino acid residues with a potential leucine zipper structure in its N-terminus, sharing low identity with other known WRKY members. OsWRKY89 and three deletion derivatives from its N-terminal were expressed in high levels in Escherichia coli as a C-terminally six-histidine-tagged fusion protein, and purified by employing one-step affinity chromatography on a Ni-NTA column. The recombinant OsWRKY89 protein was found to bind specially to sequences harboring W box cis elements by using electrophoretic mobility shift assays. This binding activity was decreased significantly by deletion of the leucine zipper-like structure in the N-terminal of Os- WRKY89. Using a yeast two-hybrid assay system, we found that the leucine zipper motif of OsWRKY89 was involved in the protein-protein interaction. Further deletion to remove partial WRKY domain abolished completely the interaction between the expressed protein and the W boxes, indicating that the WRKY domain is essential to the DNA-binding. These data strongly suggest that the leucine zipper-like motif of OsWRKY89 plays a significant role in the protein-protein and DNA-protein interactions. | WANGHaihua HAOZhongna XiEKe WUKunlu GUOZejian | 2005 | Chinese Science Bulletin2005，50，10： | 7 |
| 2 | Expression of Cryptogein in tobacco plants exhibits enhanced disease resistance and tolerance to salt stress显示文摘Cryptogein (Crypt), an elicitin secreted from Phytophthora cryptogea, was used for genetic engineering of biotic and abiotic resistance plants. We generated trans-genic tobacco plants harboring a rice phenylalanine ammo-nia-lyase (PAL) promoter and Crypt fusion gene (PAL::Crypt) or the mutated Crypt (mutation of the lysine at the position 13 to valine) under the control CaMV35S promoter (CaMV35S::CryK13V). T2 progeny of the transgenic plants showed significantly enhanced disease resistance to patho-gens of fungal Phytophthora parasitica var nicotiana (Ppn) and Alternaria alternata, and bacterial Pseudomonas syringae pv tabaci. The amount of mRNA accumulation of Crypt and CryK13V was quite low in the transgenic lines analyzed by Northern blot, and was detected by a reverse transcription PCR method. Plants harboring PAL::Crypt construct showed faster and stronger induction of PR-1a gene after Ppn inoculation than that in the wild-type plants. The re-sults suggested that the inducible PAL promoter could rap-idly respond to pathogen attack and efficiently suppress the pathogen infection. Furthermore, the enhanced tolerance to salt stress in both of the Crypt and CryK13V expressing tobacco plants was also observed compared with that in the control plants. The constitutive expression of PR and tran-scription factor genes in the transformants was probably associated with the salt tolerance. The above observations suggested that a cross-talk between biotic and abiotic stresses existed in tobacco plants. | JIANGDonghua CHENXujunt WUKunlu GUOZejian | 2004 | Chinese Science Bulletin2004，49，8： | 1 |
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