Crown rust

The biochemical similarities of leaf and stem rust elicitors, the missing gene specificity of both elicitors, the fact that an equally active elicitor was isolated from germ tube cell walls of oat crown rust (60), together with the described reactions of different non-hosts to the stem rust elicitor led us to speculate that the isolated elicitors may play a role in the induction of general mechanisms of non-host resistance (130). Although they may be involved in the elicitation of race-cultivar specific resistance as well, race-cultivar specificity in the wheat-stem rust system clearly cannot be explained on the basis of the specificity of the isolated elicitors. One possible explanation would be the occurrence of race-cultivar specific suppressors of the resistance reaction (124,131,132). 

Isawa, K., Abe, A., Nishihara, N. Influence of diseases on the chemical composition and nutritive value of forage crops. I. Chemical composition of Italian ryegrass infected with crown rust. Ann Phytopathol Soc Japan 1974 40 86-92. 

Lancashire, J.A., Latch, G.C.M. Some effects of crown rust (Puccinia coronata Corda) on the growth of two ryegrass varieties in New Zealand. New Zealand J Agri Res 1966 9 628-640. 

Mattner, S.W. The impact of crown rust on interference between perennial ryegrass and white clover. PhD Thesis. Melbourne, Australia The University of Melbourne 1998. 

Mayama, S., Matsuura, Y., Iida, H., Tani, T. The role of avenalumin in the resistance of oat to crown rust, Puccinia coronata f.sp. axenae. Physiol Plant Pathol 1982 20 189-199. 

Plummer, R.M., Hall, R.L., Watt, T.A. The influence of crown rust (Puccinia coronata) on tiller production and survival on perennial ryegrass (Loliumpererme) plants in simulated swards. Grass Forage Sd 1990 45 9-16. 

Potter, L.R., Cagas, B., Paul, V.H., Birckenstaedt, E. Pathogenicity of some European collections of crown rust (Puccinia coronata Corda) on cultivars of perennial ryegrass. J Phytopathol 1990 130 119-126. 

Trorey, G.M. The effect of crown rust (Puccinia coronata lolii) on the yield and competitive ability of perennial ryegrass. PhD Thesis. Huddersfield, United Kingdom Huddersfield Polytechnic. 1979. 

Ueno, T. and Fukami, H. (1981) The production of phytoalexins by oat in response to crown rust, Puccina-coronata f. sp. avena. Physiol. Plant Pathol., 19, 217-226. 

Returning to the grasses, we now have positive identifications of phytoalexins in oats and rice. In oats, avenalumins I, II and III have been isolated from leaves Infected with the crown rust fungus. These three compounds are benzoxazin-4-ones substituted in the 2-position with hydroxycinnamyl residues (37), Again there is a parallel with phytoalexins of dicotyledons A simple 2-phenyl substituted benzoxazin-4-one dlanthalexln was Isolated from infected carnation leaves by French scientists in 1983 (38). 

Three compounds, avenalumin I, II, and HI (19-21), are formed in resistant lines of oats (Avena sativa, Poaceae) in response to attack by crown rust, Puccinia coronata f. sp. avenae (Fig. 7.7) (Mayama, 1983). The structures of these compounds suggest that they are derived from anthranilic acid. 

Crown rust usually seen in late summer. Pale yellow leaf flecking, followed by bright orange/yellow oval pustules. Brown rust is similar in appearance but is found in spring/ early summer. 

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