Lignin biosynthetic enzymes in stem rust infected, resistant and susceptible near-isogenic wheat lines

• Published in: Physiological and molecular plant pathology Vol. 33; no. 1; pp. 33 - 46
• Main Authors: Moerschbacher, Bruno M., Noll, Ulrike M., Flott, Berenike E., Reisener, Hans-Joachim
• Format: Journal Article
• Language: English
• Published: London Elsevier India Pvt Ltd 01.07.1988; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Generalities; Genetics and breeding of economic plants; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; Pest resistance; Phytopathology. Animal pests. Plant and forest protection; Varietal selection. Specialized plant breeding, plant breeding aims; BSA; DTT; CAD; PAL; p.i; 4CL; PO; Lignin; Puccinia graminis f. tritici; Monocotyledones; Phenylalanine ammonia-lyase; Mycosis; Basidiomycetes; Biosynthesis; Phytopathogen; Cereal crop; Fungi; Cinnamyl alcohol dehydrogenase(NADP+); Lignification; Enzymatic activity; Gramineae; Angiospermae; Peroxidase; Thallophyta; Enzymatic synthesis; Hypersensitivity; Host agent relation; Fungus resistance; Infection; Sensitivity resistance; Defense mechanism; Spermatophyta; 4-Coumaroyl-CoA synthetase; Isogenic line; Triticum aestivum
• ISSN: 0885-5765; 1096-1178
• DOI: 10.1016/0885-5765(88)90041-0

Near-isogenic lines of the wheat cultivar Prelude, carrying either the Sr5 gene for resistance or the sr5 allele for susceptibility were inoculated with the stem rust fungus Puccinia graminis f. sp. tritici race 32, which possesses the P5 gene for avirulence. The time-course of the enzyme activities of the general phenylpropanoid pathway, phenylalanine ammonia-lyase (PAL) and 4-coumarate:CoA ligase (4CL), as well as the enzyme activities of the specific pathway leading to the biosynthesis of lignin, cinnamyl-alcohol dehydrogenase (CAD) and peroxidase (PO), were determined. The resistant and the susceptible isoline both exhibit a first maximum in the coordinately regulated enzyme activities of PAL and 4CL at a time when the fungus is still growing on the surface of the leaves. This maximum is followed by a decrease to the levels of uninoculated controls. In the resistant isoline, a second increase is observed at the time of the hypersensitive resistant reaction. In contrast, enzyme activities in susceptible plants continue to decline, even falling below control levels until the onset of sporulation when a second, late increase can be detected. The observed changes in CAD and PO activities are consistent with a feed-forward regulation by products of the general phenylpropanoid pathway. However, no late increase in PO activity can be observed in the compatible interaction. An interpretation of these results is proposed in terms of non-host resistance, basic compatibility and race-cultivar specific resistance.