ABSTRACT
Plant organisms possess a complex set of defence mechanisms that are responsible for preventing unfavourable interactions with other living organisms in their natural environment or for reducing negative effects of such interactions. They can be classified into two groups: early responses that occur immediately or shortly after contact with a pathogenic organism, usually in the proximity of the infection site, and late, usually transcription- and translation-dependent responses that take part in minimizing the long-term effects of the infection and in preventing further infections. Early responses are a mixture of distinct biochemical processes, leading to quick activation of enzymes, structural changes in components of the living cell, alteration of biochemical pathways and synthesis of intra- and intercellular signals. An important part of early responses are redox processes, especially the synthesis of large amounts of reactive oxygen species.
Subject(s)
Plant Diseases , Plants/metabolism , GTP-Binding Proteins/metabolism , Genes, Plant , Ion Channels/metabolism , Plant Diseases/genetics , Plant Proteins/metabolism , Plants/genetics , Reactive Oxygen Species/metabolism , Respiratory Burst , Signal TransductionABSTRACT
The ornithine transaminase (otaA) gene of Aspergillus nidulans has been cloned by transformation of the A. nidulans pro-ota- mutant strain with a cosmid gene library. The otaA gene contains two introns and potentially codes for a 453-aa-long protein. The deduced amino-acid sequence is homologous to known ornithine transaminases from Saccharomyces cerevisiae, Plasmodium falciparum, Vigna aconitifolia, rat, mouse and man, particularly in the pyridoxal phosphate-binding domain. The expression of the otaA gene is specifically induced by arginine, and is also under the control of nitrogen-metabolite and carbon-catabolite repression. Regulation of the gene occurs at both transcriptional and post-transcriptional levels. The promoter region of otaA contains putative AREA and CREA binding-sites. Fusion proteins containing AREA or CREA DNA-binding domains bind some of these sites. CREA binding-sites correspond very well to the CREA-binding consensus sequence which is SYGGRG. AREA binding-sites are composed of GATT sequences which are not typical binding sites for the GATA - binding family of transcription factors.
Subject(s)
Aspergillus nidulans/genetics , Ornithine-Oxo-Acid Transaminase/genetics , Amino Acid Sequence , Aspergillus nidulans/enzymology , Aspergillus nidulans/growth & development , Base Sequence , Binding Sites , Cloning, Molecular , DNA, Fungal/chemistry , DNA, Fungal/genetics , Fungal Proteins/metabolism , Gene Expression Regulation, Enzymologic , Gene Expression Regulation, Fungal , Genes, Fungal/genetics , Molecular Sequence Data , Ornithine-Oxo-Acid Transaminase/metabolism , Promoter Regions, Genetic , Repressor Proteins/metabolism , Sequence Analysis, DNA , Sequence Homology, Amino Acid , Transcription Factors/metabolism , Transcription, GeneticABSTRACT
Soybean beta-1,3-endoglucanase represents a model system for studies on early plant responses to infection by fungal pathogens, and it has been implicated in the release of elicitors from fungal cell walls. In the present study, potato plants were transformed with the soybean beta-1,3-endoglucanase cDNA via Agrobacterium delivery system. The transfer of the gene into potato genome was confirmed by (i) PCR amplification, (ii) Northern blot analyses, and (iii) an increase in the activity of beta-1,3-endoglucanase in transgenic plants. The transformation resulted in an increased resistance of selected transgenic plants to infection by Phytophthora infestans, an important pathogen.
