Comparison of various stress responses in oat in compatible and nonhost resistant interactions with rust fungi

Abstract

The role of extracellular fl-1,3-glucanases and chitinases was investigated in oat leaves after infection with different rust fungi . The oat leaves (Avena sativa L .) were inoculated with the compatible rust Puccinia coronata f. sp . avenae and the two nonpathogens Puccinia recondita f. sp . tritici and Puccinia graminis f. sp. tritici . No alterations in enzyme activities were found in the compatible interaction . In the nonhost interaction with P. recondita ff sp . tritici (1-1,3-glucanase and chitinase activities increased by 100 % 24 h after infection. With P . graminis f. sp . tritici the activities of both enzymes increased about twofold after 48 h . In both nonhost interactions the observed increase in activity was due to the induction of an acidic fl-1,3-glucanase and a chitinase whereas the activity of the basic enzymes did not change . This increase is small compared to other systems and apparently the enzymes are not able to inhibit growth of the different rust fungi . Treatment of noninfected plants with the abiotic stress factor mercuric chloride induced necrosis and production of avenalumins but had no effect on the activities of the two enzymes investigated . In the nonhost systems no alteration of peroxidase activity and no induction of avenalumins could be found . Our results indicate that mechanisms other than the stress responses of oat plants studied so far are active in nonhost resistance .

cDNA Clones Encoding 1,3-β-Glucanase and a Fimbrin-Like Cytoskeletal Protein Are Induced by Al Toxicity in Wheat Roots

“…Our observation that Al toxicity induces a l,3-|3-glucanase is consistent with previous reports that these enzymes are induced by other metal ions including Co, Ba, Mn, Hg, and Ag (Fink et al, 1990). Generally, l,3-/3-glucanases play an important role in defense against fungal attack in both dicotyledonous and monocotyledonous plants (Simmons, 1994); however, their role in metal toxicity is not known.…”

Insight into Types I and II nonhost resistance using expression patterns of defense-related genes in tobacco

“…According to an earlier hypothesis (Goodman and Novacky 1994;Agrios 1997), incompatible pathogens must induce the HR phenotype in a nonhost plant. However, more recent data have shown that even pathogenic bacteria, which cause severe symptoms on a host plant, will not induce HR on a nonhost plant (Fink et al 1990;Jakobek and Lindgren 1993;Kamoun et al 1998;Klement et al 1999). These results indicated a requirement for a new model to explain Type I nonhost resistance.…”

Occurrence of Avenanthramides and Hydroxycinnamoyl-CoA:hydroxyanthranilate N-hydroxycinnamoyltransferase Activity in Oat Seeds

“…avenae) in incom patible com binations (M ayam a et al, 1982; M ayam a et al, 1981). The induction of avenanthram ides can be reproduced by tre atm e n t w ith elicitors such as Nacetylchitooligosaccharides (B ordin et al, 1991), victorin C (M ayam a et al, 1986), heavy m etal ions (Fink et al, 1990), and the calcium ionophore A23187 . In addition, the oc currence of avenanthram ides in oat grains and hulls as constitutive com ponents has been found (Collins, 1986;Collins, 1989;Collins et a l, 1991).…”