https://dspace.library.uu.nl/bitstream/handle/1874/1590/PMPP-van+Loon-1999.pdf?sequence=1

The families of pathogenesis-related proteins, their activities, and comparative analysis of PR-1 type proteins

We demonstrated that the GCC box, which is an 11-bp sequence (TAAGAGCCGCC) conserved in the 59 upstream region of ethylene-inducible pathogenesis-related protein genes in Nicotiana spp and in some other plants, is the sequence that is essential for ethylene responsiveness when incorporated into a heterologous promoter. Competitive gel retardation assays showed DNA binding activities to be specific to the GCC box sequence in tobacco nuclear extracts. Four different cDNAs encoding DNA binding proteins specific for the GCC box sequence were isolated, and their products were designated ethylene-responsive element binding proteins (EREBPs). The deduced amino acid sequences of EREBPs exhibited no homology with those of known DNA binding proteins or transcription factors; neither did the deduced proteins contain a basic leucine zipper or zinc finger motif. The DNA binding domain was identified within a region of 59 amino acid residues that was common to all four deduced EREBPs. Regions highly homologous to the DNA binding domain of EREBPs were found in proteins deduced from the cDNAs of various plants, suggesting that this domain is evolutionarily conserved in plants. RNA gel blot analysis revealed that accumulation of mRNAs for EREBPs was induced by ethylene, but individual EREBPs exhibited different patterns of expression.

/pdf/ethylene-inducible-dna-binding-proteins-that-interact-with-37k5oxkd1q.pdf

Ethylene-inducible DNA binding proteins that interact with an ethylene-responsive element.

Plant chitinases

Plant ‘pathogenesis-related’ proteins and their role in defense against pathogens

Infection of plants with pathogens like viruses or fungi often leads to a response of the host ranging from very mild to very severe. A very mild response usually does not result in considerable changes in the patterns of gene expression of the plant. However, a hypersensitive reaction, e.g., in the case of infection of Samsun NN tobacco with tobacco mosaic virus, is accompanied by a massive increase in the amounts of a large number of different proteins. Among these induced proteins are members of a group of so‐called pathogenesis‐related (PR) proteins. Frequently, the hypersensitively reacting host becomes resistant to subsequent pathogenic attack. The correlation of this phenomenon of acquired resistance and the induced protein synthesis suggests a direct involvement of these proteins in the observed replication deficiency of the pathogen. This has initiated studies by several research groups toward a better understanding of the role of these PR‐proteins in the hypersensitively reacting plant....

Pathogenesis-related proteins of plants

Sequence analysis of five gene families that were isolated from tobacco thin cell layer explants initiating floral development [Meeks-Wagner et al. (1989). Plant Cell 1, 25-35] showed that two encode the pathogenesis-related proteins basic chitinase and basic beta-1,3-glucanase, while a third encodes the cell wall protein extensin, which also accumulates during pathogen attack. Another sequence family encodes the water stress-induced protein osmotin [Singh et al. (1989). Plant Physiol. 90, 1096-1101]. We found that osmotin was also induced by viral infection and wounding and, hence, could be considered a pathogenesis-related protein. These genes, which were highly expressed in explants during de novo flower formation but not in explants forming vegetative shoots [Meeks-Wagner et al. (1989). Plant Cell 1, 25-35], were also regulated developmentally in day-neutral and photoresponsive tobacco plants with high expression levels in the roots and moderate- to low-level expression in other plant organs including flowers. An unidentified gene family, FB7-4, had its highest level of expression in the basal internodes. Our findings indicate that these genes, some of which are conventionally considered to encode pathogen-related proteins, also have a complex association with normal developmental processes, including the floral response, in healthy plants.

H T Bonnett

Papers

Chitinase, beta-1,3-glucanase, osmotin, and extensin are expressed in tobacco explants during flower formation.