Cold-induced changes in cell wall stability determine the resistance of winter triticale to fungal pathogen Microdochium nivale

The exposure of winter triticale to cold promotes genotype-dependent resistance to fungal pathogen. We present the evidence that structural and chemical modifications of the cell wall components induced by cold can be correlated with the resistance against fungal infection. Our results showed that cellulose of hardened triticale cv. Hewo (able to develop resistance after cold treatment) has more compact and integrated structure, thicker and longer fibres when compared to cv. Magnat (susceptible to fungal infection despite plant hardening). Such structure of cellulose limits water sorption, favours stronger bonding the water of crystallisation to macromolecules, impedes depolymerisation process during decomposition, and finally results in higher thermal stability of cell wall. Furthermore, the lignin composition is drastically modified in resistant plants. Pattern of the thermal decomposition indicates higher molecular mass and more complex structure of lignin, followed by the higher thermal stability. We conclude that specific structure of lignocellulosic cell wall of the resistant plants forms a barrier for fungal enzymes digesting host tissue as well as can resist better the mechanical pressure of hyphae.