Key message Snow mold resistance is a complex quantitative trait highly affected by environmental conditions during winter that must be addressed by resistance breeding. Abstract Snow mold resistance in winter cereals is an important trait for many countries in the Northern Hemisphere. The disease is caused by at least four complexes of soilborne fungi and oomycetes of which Microdochium nivale and M. majus are among the most common pathogens. They have a broad host range covering all winter and spring cereals and can basically affect all plant growth stages and organs. Their attack leads to a low germination rate, and/or pre- and post-emergence death of seedlings after winter and, depending on largely unknown environmental conditions, also to foot rot, leaf blight, and head blight. Resistance in winter wheat and triticale is governed by a multitude of quantitative trait loci (QTL) with mainly additive effects highly affected by genotype × environment interaction. Snow mold resistance interacts with winter hardiness in a complex way leading to a co-localization of resistance QTLs with QTLs/genes for freezing tolerance. In practical breeding, a multistep procedure is necessary with (1) freezing tolerance tests, (2) climate chamber tests for snow mold resistance, and (3) field tests in locations with and without regularly occurring snow cover. In the future, resistance sources should be genetically characterized also in rye by QTL mapping or genome-wide association studies. The development of genomic selection procedures should be prioritized in breeding research.

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.

Rye genetic resources provide a valuable source of new alleles for the improvement of frost tolerance in rye breeding programs. Frost tolerance is a must-have trait for winter cereal production in northern and continental cropping areas. Genetic resources should harbor promising alleles for the improvement of frost tolerance of winter rye elite lines. For frost tolerance breeding, the identification of quantitative trait loci (QTL) and the choice of optimum genome-based selection methods are essential. We identified genomic regions involved in frost tolerance of winter rye by QTL mapping in a biparental population derived from a highly frost tolerant selection from the Canadian cultivar Puma and the European elite line Lo157. Lines per se and their testcrosses were phenotyped in a controlled freeze test and in multi-location field trials in Russia and Canada. Three QTL on chromosomes 4R, 5R, and 7R were consistently detected across environments. The QTL on 5R is congruent with the genomic region harboring the Frost resistance locus 2 (Fr-2) in Triticeae. The Puma allele at the Fr-R2 locus was found to significantly increase frost tolerance. A comparison of predictive ability obtained from the QTL-based model with different whole-genome prediction models revealed that besides a few large, also small QTL effects contribute to the genomic variance of frost tolerance in rye. Genomic prediction models assigning a high weight to the Fr-R2 locus allow increasing the selection intensity for frost tolerance by genome-based pre-selection of promising candidates.

Microdochium nivale is a progressive and devastating phytopathogen that causes different types of cereal crop and grass diseases that are poorly characterized at the molecular level. Although rye (Secale cereale L.) is one of the most resistant crops to most of the phytopathogens, it is severely damaged by M. nivale. The recent high-quality chromosome-scale assembly of rye genome has improved whole-genome studies of this crop. In the present work, the first transcriptome study of the M. nivale-infected crop plant (rye) with the detailed functional gene classification was carried out, along with the physiological verification of the RNA-Seq data. The results revealed plant reactions that contributed to their resistance or susceptibility to M. nivale. Phytohormone abscisic acid was shown to promote plant tolerance to M. nivale. Flavonoids were proposed to contribute to plant resistance to this pathogen. The upregulation of plant lipase encoding genes and the induction of lipase activity in M. nivale-infected plants revealed in our study were presumed to play an important role in plant susceptibility to the studied phytopathogen. Our work disclosed important aspects of plant-M. nivale interactions, outlined the directions for future studies on poorly characterized plant diseases caused by this phytopathogen, and provided new opportunities to improve cereals breeding and food security strategies.

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A b s t r a c tVarieties intended for diverse use are modern priority in winter rye (Secale cereale L.) breeding. Composition and content of pentosans are indicators to diversify rye grain use. The aim of this work was estimation of variability in total arabinoxylans and soluble arabinoxylans in rye grain. Pentosans content was determined by high performance liquid chromatography in the HPLC-RI system (JASCO Deutschland GmbH, Germany), by chemical micro method with use of orcinchloride, and indirectly by determining the viscosity of water extract (VWE). As a result, the samples with low and high pentosan content were identified at the linear, population and hybrid level in domestic and foreign gene pools. It was shown that Russian population varieties and high-pentosan lines selected at Tatar Research Institute of Agriculture stood out due to high rates of general pentosan level and extracted viscosity. The relationship between VWE and the content of water-soluble pentosans in the studied quantitative limits with a high probability (95 %) has a rectilinear character. In low pentosans lines originated from Tatar Research Institute of Agriculture VWE amounted to 6.40-of 6.45 centistokes (sSt), in the domestic population varieties VWE ranged from 15.40 to 34.50 sSt, and in hybrid varieties from Germany VWE reached 47.50 sSt. So we have a gene pool sufficient for baking rye breeding. In high-pentosan forms, we found the high significant positive correlation between the total content of pentosans, viscosity of water extracts and water-soluble fraction. An indirect estimate of pentosans fraction through determination of the water extract viscosity of rye meal allows to start selection in the early steps of breeding and to analyze a large number of samples in a relatively short time. Further search is necessary to select donor lines with low total level of arabinoxylans and water-soluble fraction. It is difficult to phenotypically evaluate low-pentosans plants based on an indirect indicator of viscosity only. Low pentosan lines had a significant correlation between VWE and the water-soluble fraction (r = 0.745, Р = 0.05). Heritability of water extract viscosity of grain meal was rather high (H 2 = 0.71), and genotypic variation coefficient reached 32.53 %, indicating advisability of VWE improving by breeding techniques. Heritability index of water-soluble pentosan content was 0.50, and genotypic coefficient of variation was 13.02 %, so the impact of breeding on these indicators should be low. The presented genotypic variability parameters are applicable only to the genotypes used in our experiment. The smallest amounts of water-soluble pentosans in flour and meal were characteristic of the Russian varieties Marusenka, Ogonek, Chulpan 7. We revealed a low content of water-soluble fraction in the bran in variety Ogonek. To distinguish rye genotypes more precisely, it is necessary to develop effective tests which will allow to assess water absorption, viscosity and solubility of pentosans (high-molecular arabinoxylans) in ...

The purpose of the current work was to develop a highly productive winter rye variety for bakery with improved resistance to a complex of unfavorable factors and broad adaptability. The breeding work on the rye variety ‘Zilant’ was conducted in the Tatarsky Research Institute of Agriculture FRC of the Kazan Scientific Center of RAS in 2005–2015. The study of the variety in the Competitive Variety Testing was carried out in 2016–2019, in comparison with the standard varieties ‘Radon’ and ‘Tantana’. There has been presented a detailed characteristics of the variety ‘Zilant’ in terms of economically valuable indicators and adaptive potential according to grain productivity. The winter rye variety ‘Zilant’ formed the largest productivity on average for 4 years (50.2 hwt/ha) and produced high grain quality (229 s of a falling number and 647 u.a. of amylogram height, versus 224 s of a falling number and 625 u.a. of amylogram height of the standard variety ‘Radon’). The variety ‘Zilant’ has a dominant-monogenic type of short stems, strong short straw (on 14–13 cm lower than that of the standards). The variety possesses the same degree of field resistance to rust infections and ergot, resistance to powdery mildew as the standard variety ‘Radon’. There was determined that the rye variety ‘Zilant’, on average over the years of trials, was characterized by a significantly higher productivity (50.2 hwt/ ha, НСР05 = 1.5 c/ha) compared to the control, had a good combination of adaptability (bi = 1.149) and stability (Ϭd2 = 3.17). These advantages of the variety are provided by resistance to unfavorable environmental conditions, the formation of a denser cenosis, field resistance to diseases, and a short non-lodging stem. The rye variety ‘Zilant’ produced grain with high baking qualities, corresponding to the 1st class of standards for grain and flour. The variety was responsive to improving growing conditions, showed less response to stress factors and was adapted to a wide range of environmental conditions.