Specific inhibition of lignification breaks hypersensitive resistance of wheat to stem rust

• Published in: Plant physiology (Bethesda) 1990-06, Vol.93 (2), p.465-470
• Main Authors: Moerschbacher, B.M. (Institut fur Biologie III, Aachen, FRG), Noll, U, Gorrichon, L, Reisener, H.J
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Cell growth; Enzymes; Fundamental and applied biological sciences. Psychology; Fungi; Genetics and breeding of economic plants; Hypersensitivity; Leaves; LIGNIFICACION; LIGNIFICATION; Lignin; Microbe-Plant Interactions; Mother cells; PARASITISME; PARASITISMO; Pest resistance; Plant pathogens; Plants; PODER INFECCIOSO; PODER PATOGENO; POUVOIR INFECTANT; POUVOIR PATHOGENE; PUCCINIA; RESISTANCE AUX MALADIES; RESISTENCIA A LA ENFERMEDAD; Rust fungi; TRITICUM AESTIVUM; VARIEDADES; Varietal selection. Specialized plant breeding, plant breeding aims; VARIETE
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.93.2.465

When highly resistant wheat (Triticum aestivum L.) varieties are infected by an avirulent race of the stem rust fungus (Puccinia graminis Pers. f. sp. tritici Erics. and E. Henn.), penetrated host cells undergo rapid necrotization. This hypersensitive cell death is correlated with cellular lignification which efficiently restricts further fungal growth. Three competitive inhibitors of phenylalanine ammonia-lyase, the first enzyme of the general phenylpropanoid pathway and, thus, of lignin biosynthesis, namely alpha-aminooxyacetate, alpha-aminooxy-beta-phenylpropionic acid, and (1-amino-2-phenylethyl)phosphonic acid, and two highly specific irreversible suicide inhibitors of the lignification-specific enzyme cinnamyl-alcohol dehydrogenase, namely N(O-aminophenyl)sulfinamoyl-tertiobutyl acetate and N(O-hydroxyphenyl)sulfinamoyltertiobutyl acetate, were applied to genetically resistant wheat plants prior to inoculation with stem rust. Treatment with any of these inhibitors decreased the frequency of lignified necrotic host cells and concomitantly led to increased fungal growth. The cinnamyl-alcohol dehydrogenase inhibitors were generally more effective than the phenylalanine ammonia-lyase inhibitors, occasionally allowing some sporulation to occur on the resistant wheat leaves. These results clearly point to a causal relationship between the formation of lignin precursors and the resistance of wheat to stem rust