Cold-hardening of winter triticale (x Triticosecale Wittm.) results in increased resistance to pink snow mould Microdochium nivale (Fr., Samuels & Hallett) and genotype-dependent chlorophyll fluorescence modulations

Abstract

The resistance of triticale (x Triticosecale Wittm.) to infection of snow mould Microdochium nivale (Fr., Samuels & Hallett) was examined under different temperature pre-treatment regimes. The results of laboratory ''cold chamber'' resistance tests correlated with the breeders' report from field experiments. Studied genotypes differed substantially in their resistance to infection. Two cultivars: 'Magnat' (susceptible) and 'Hewo' (relatively resistant) were further studied as a plant model to test the role of pre-hardening and cold-hardening induction of resistance expression. Both model cultivars were susceptible to M. nivale infection without cold pre-treatment and gained genotype-depended level of resistance after 4 weeks treatment at 4°C, moreover the resistance grew gradually. Simultaneously to the resistance tests, the measurements of chlorophyll fluorescence parameters were taken. The results showed that higher vitality index Rfd of coldhardened triticale seedlings correlated with increased pink snow mould resistance while differences in other parameters of fluorescence were not distinctly significant. Establishment of Rfd in 4 weeks hardened triticale seedlings could be used for a large scale screening of breeding material in order to select potentially resistant genotypes. Such analyses have not been reported for triticale before.

Microdochium nivale (Fr., Samuels & Hallett): cytological analysis of the infection process in triticale (×Triticosecale Wittm.)

“…The experiments were carried out according to the 'cold chamber' method described by Cormack and Lebeau (1959) modified by Pronczuk et al (2003) and Golebiowska and Wedzony (2009). Two cultivars of hexaploid winter triticale (9Triticosecale Wittm., 2n = 6x = 42) that differed in resistance to M. nivale in previous experiments, both at laboratory and field conditions (Golebiowska and Wedzony 2009), were used for the present study, i.e.…”

“…Two cultivars of hexaploid winter triticale (9Triticosecale Wittm., 2n = 6x = 42) that differed in resistance to M. nivale in previous experiments, both at laboratory and field conditions (Golebiowska and Wedzony 2009), were used for the present study, i.e. susceptible cv.…”

“…The main hosts of M. nivale are wheat, rye, barley, oats, turf and forage grasses (Tronsmo et al 2001). Among others, M. nivale infects winter triticale (Cichy and Maćkowiak 1993;Golebiowska and Wedzony 2009), the man-made cereal obtained by initial crossing wheat (Triticum vulgare) with rye (Secale cereale) and further stabilization of the allopolyploid with the use of laboratory methods (Ryöppy 1997). The economic importance of triticale grows fast but both the quality and the quantity of its yield is regularly under the threat of pathogenic infection.…”

“…Moreover, available fungicides are not sufficiently efficient and have negative impact on the environment. Published data (Nakajima and Abe 1996; Ergon et al 1998;Golebiowska and Wedzony 2009) report that maximal snow mould resistance develops only in cold-hardened plants and varies among genotypes. Whereas the majority of pathogens are less aggressive and unable to infect plants at freezing temperatures, some psychrophilic pathogens, including M. nivale, are able to invade plants under these conditions and cause significant damage (Tronsmo et al 2001).…”

“…Thus, the aim of the present study was to analyse the interaction between M. nivale hyphae and the host cells of resistant and susceptible plants in controlled conditions by the use of light and fluorescence microscopy. Model genotypes were selected in our previous experiments (Golebiowska and Wedzony 2009). Such studies, providing better insight into mechanisms of the host-pathogen interactions would be highly expected and may allow elaborating efficient breeding strategies towards increased pink snow mould resistance.…”