Rye Snow Mold-Associated Microdochium nivale Strains Inhabiting a Common Area: Variability in Genetics, Morphotype, Extracellular Enzymatic Activities, and Virulence

Abstract

Snow mold is a severe plant disease caused by psychrophilic or psychrotolerant fungi, of which Microdochium species are the most harmful. A clear understanding of Microdochium biology has many gaps; the pathocomplex and its dynamic are poorly characterized, virulence factors are unknown, genome sequences are not available, and the criteria of plant snow mold resistance are not elucidated. Our study aimed to identify comprehensive characteristics of a local community of snow mold-causing Microdochium species colonizing a particular crop culture. By using the next-generation sequencing (NGS) technique, we characterized fungal and bacterial communities of pink snow mold-affected winter rye (Secale cereale) plants within a given geographical location shortly after snowmelt. Twenty-one strains of M. nivale were isolated, classified on the basis of internal transcribed spacer 2 (ITS2) region, and characterized by morphology, synthesis of extracellular enzymes, and virulence. Several types of extracellular enzymatic activities, the level of which had no correlations with the degree of virulence, were revealed for Microdochium species for the first time. Our study shows that genetically and phenotypically diverse M. nivale strains simultaneously colonize winter rye plants within a common area, and each strain is likely to utilize its own, unique strategy to cause the disease using “a personal” pattern of extracellular enzymes.

Resistance to Snow Mold as a Target Trait for Rye Breeding

“…This is due to the fact that a small amount of breeding material with increased SM resistance is used in contemporary breeding. We searched the SM resistance sources in the Tatarstan Republic, where a fairly high level of SM is a typical situation [ 46 ], for two years in which the level of natural development of the disease was different: in 2021, the level of SM was significantly higher than in 2020. The variation in SM severity during two years of observation was likely related to different durations of snow cover—102 and 150 days in 2020 and 2021, respectively ( Table 6 )—which is consistent with the confinement of SM outbreaks to prolonged periods of snow cover [ 21 , 22 ].…”

“…Samuels & I.C. Hallett strain F00628 from the collection of KSC [ 46 ]. In 2019, the inoculum was prepared as follows: M. nivale was grown in potato-sucrose medium for 20 days in darkness at 20 °C.…”

New opportunities in plant microbiome engineering for increasing agricultural sustainability under stressful conditions

“…Although plants bring beneficial microorganisms, such as PGPR and diseasesuppressing microorganisms, it has been evident that they can also bring phytopathogens as well as human pathogenic bacteria. These harmful bacteria may enter the food chain, can cause plant disease, and can alter the entire microbiome composition (Gorshkov et al, 2020). Therefore, tools such as metagenomics, for example, offer a promising strategy to diagnose these phytopathogens (Chiu and Miller, 2019).…”

OMICs, Epigenetics, and Genome Editing Techniques for Food and Nutritional Security

“…Although the selection mechanisms used by plants significantly enrich the plant microbiome with beneficial microorganisms, such as plant growth-promoting rhizobacteria (PGPR) [ 76 ] and disease suppressing microorganisms [ 76 , 82 , 83 ], many researchers have shown that the rhizosphere and all plant compartments often contain both phytopathogens and human pathogenic bacteria as well as producers of toxins that can enter the food chain directly from plants [ 84 , 85 , 86 ]. Moreover, if a plant disease occurs, it not only promotes the multiplication of the pathogen, but is also accompanied by dramatic changes in the entire microbiome [ 87 ]. In this regard, metagenomics is a promising tool for phytopathogen diagnosis, and food quality control, as well as developing clinical metagenomics [ 88 ].…”