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Query: UMLS:C0851341 (infestation)
 10,121 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxalic acid is present as nutritional stress in many crop plants like Amaranth and Lathyrus. Oxalic acid has also been found to be involved in the attacking mechanism of several phytopathogenic fungi. A full-length cDNA for oxalate decarboxylase, an oxalate-catabolizing enzyme, was isolated by using 5'-rapid amplification of cDNA ends-polymerase chain reaction of a partial cDNA as cloned earlier from our laboratory (Mehta, A., and Datta, A. (1991) J. Biol. Chem. 266, 23548-23553). By screening a genomic library from Collybia velutipes with this cDNA as a probe, a genomic clone has been isolated. Sequence analyses and comparison of the genomic sequence with the cDNA sequence revealed that the cDNA is interrupted with 17 small introns. The cDNA has been successfully expressed in cytosol and vacuole of transgenic tobacco and tomato plants. The transgenic plants show normal phenotype, and the transferred trait is stably inherited to the next generation. The recombinant enzyme is partially glycosylated and shows oxalate decarboxylase activity in vitro as well as in vivo. Transgenic tobacco and tomato plants expressing oxalate decarboxylase show remarkable resistance to phytopathogenic fungus Sclerotinia sclerotiorum that utilizes oxalic acid during infestation. The result presented in the paper represents a novel approach to develop transgenic plants resistant to fungal infection.
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PMID:Oxalate decarboxylase from Collybia velutipes. Molecular cloning and its overexpression to confer resistance to fungal infection in transgenic tobacco and tomato. 1070 93

Rising atmospheric CO(2) levels can dilute the nitrogen (N) resource in plant tissue, which is disadvantageous to many herbivorous insects. Aphids appear to be an exception that warrants further study. The effects of elevated CO(2) (750 ppm vs. 390 ppm) were evaluated on N assimilation and transamination by two Medicago truncatula genotypes, a N-fixing-deficient mutant (dnf1) and its wild-type control (Jemalong), with and without pea aphid (Acyrthosiphon pisum) infestation. Elevated CO(2) increased population abundance and feeding efficiency of aphids fed on Jemalong, but reduced those on dnf1. Without aphid infestation, elevated CO(2) increased photosynthetic rate, chlorophyll content, nodule number, biomass, and pod number for Jemalong, but only increased pod number and chlorophyll content for dnf1. Furthermore, aphid infested Jemalong plants had enhanced activities of N assimilation-related enzymes (glutamine synthetase, Glutamate synthase) and transamination-related enzymes (glutamate oxalate transaminase, glutamine phenylpyruvate transaminase), which presumably increased amino acid concentration in leaves and phloem sap under elevated CO(2). In contrast, aphid infested dnf1 plants had decreased activities of N assimilation-related enzymes and transmination-related enzymes and amino acid concentrations under elevated CO(2). Furthermore, elevated CO(2) up-regulated expression of genes relevant to amino acid metabolism in bacteriocytes of aphids associated with Jemalong, but down-regulated those associated with dnf1. Our results suggest that pea aphids actively elicit host responses that promote amino acid metabolism in both the host plant and in its bacteriocytes to favor the population growth of the aphid under elevated CO(2).
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PMID:Pea aphid promotes amino acid metabolism both in Medicago truncatula and bacteriocytes to favor aphid population growth under elevated CO2. 2368 68