Effect of cold‐induced changes in physical and chemical leaf properties on the resistance of winter triticale (×Triticosecale) to the fungal pathogen Microdochium nivale

Abstract

This study showed that several mechanisms of the basal resistance of winter triticale to Microdochium nivale are cultivar-dependent and can be induced specifically during plant hardening. Experiments and microscopic observations were conducted on triticale cvs Hewo (able to develop resistance after cold treatment) and Magnat (susceptible to infection despite hardening). In cv. Hewo, cold hardening altered the physical and chemical properties of the leaf surface and prevented both adhesion of M. nivale hyphae to the leaves and direct penetration of the epidermis. Cold-induced submicron-and micron-scale roughness on the leaf epidermis resulted in superhydrophobicity, restricting fungal adhesion and growth, while the lower permeability and altered chemical composition of the host cell wall protected against tissue digestion by the fungus. The fungal strategy to access the nutrient resources of resistant hosts is the penetration of leaf tissues through stomata, followed by biotrophic intercellular growth of individual hyphae and the formation of haustoria-like structures within mesophyll cells. In contrast, a destructive necrotrophic fungal lifestyle occurs in susceptible seedlings, despite cold hardening of the plants, with the host epidermis, mesophyll and vascular tissues being digested and becoming disorganized as a result of the low chemical and mechanical stability of the cell wall matrix. This work indicates that specific genetically encoded physical and mechanical properties of the cell wall and leaf tissues that depend on cold hardening are factors that can determine plant resistance against fungal diseases.

The effects of cold-hardening and Microdochium nivale infection on oxidative stress and antioxidative protection of the two contrasting genotypes of winter triticale

“…Hewo and as a necrotroph in susceptible tissue of cv. Magnat [46]. Here, we suggest that a similar relationship may occur for the tested genotypes.…”

Application of a device used for observation of controlled thermal processes in a furnace

“…The first DSC peak could be attributed to the decomposition of hemicellulose [25], although the values obtained in this study were slightly higher than the usual range attributed to hemicellulose thermal decomposition, from 270 to 281°C [31]. The second peak is usually regarded as cellulose degradation step [5]. Hemicelluloses present lower thermal stability than cellulose due to the fact that they are amorphous, whereas cellulose is crystalline [32].…”

“…In most cases it is impossible to directly or simultaneously observe the visual changes taking place in the studied materials. Currently, in modern test equipment it is common to include the so-called coupled methods (allowing to perform several independent measurements at the same time, e.g., the measurement cycle in differential scanning calorimetry/thermogravimetry/quadrupole mass spectrometry; DSC/TG/QMS), which facilitate interpretation of the registered thermal effects, mass changes or released gas products [1][2][3][4][5][6][7][8][9]. From the results it can be concluded which phenomena are being dealt with, but observation of the sample can be conducted only before and/or after the experiment.…”

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

“…For successful colonisation, pathogens must gain access to the cellular nutrients breaking of the plant cell wall with enzymes and/or with high turgor pressure created inside the invasion structures [1]. Conversely, plant responds to fungal invasion by remodelling and reinforcing the cell wall [2,3], by inhibiting fungal enzymes that can degrade the host cell wall and by killing pathogens via antimicrobial means [4].…”

“…The proportion of cellulose, lignin and other polysaccharides may change, when the suboptimal temperature, limited water availability and light modulation affect plant growth and development [2,7,8]. Therefore, abiotic and biotic stresses are often physiologically interrelated and can induce similar responses at the level of cell wall.…”