Triticum aestivum L. is one of the most important cereal food crops, but its production is limited by numerous biotic and abiotic factors. The leading role in the pathogenesis is played by representatives of the genus Fusarium Link, which are characterized by a wide range and occupy different ecological niches.
Studies on resistance to Fusarium graminearum are rare today, and the mechanisms of heritability of the trait in hybrid organisms, depending on the original forms, including the sources of resistance created in previous years, remain insufficiently studied. Therefore, it is relevant to determine the nature of inheritance of resistance against the pathogen Fusarium graminearum Schwabe (F. graminearum) in hybrids F1. Triticum aestivum L.
The aim of the research is to create infectious material and background of the pathogen and phenotypes analysis of F1 hybrids of winter bread wheat for resistance to pathogen F. graminearum.
Experiments on the analysis of wheat genotypes F1, for resistance to F. graminearum were established in field infectious and natural nurseries of the V.M. Remeslo Myronivka Institute of Wheat of the National Academy of Agrarian Sciences of Ukraine (MIW) in the Winter Wheat Breeding Laboratory during 2021-2023. 22 hybrid combinations F1, created in 2020-2022 served as the material for the research. Sources of resistance (MV 20-88 / Smuglyanka, BILINMEVEN-49 / Natalka, Donskoy Prostor / Slavna, Myronivska rannostyhla / Catalon and (Mikon / ALMA) /Legenda Myronivska) against F. graminearum of bread winter wheat and new local breeding varieties (MIP Knyazhna, MIP Fortuna, MIP Vyshyvanka, Aurora Myronivska, Podolyanka) as a result of direct and reverse crosses of soft winter wheat varieties of the MIW winter wheat breeding laboratory. Seeds of hybrids were sown manually, according to the scheme: maternal form, hybrid, paternal form (pollinator). The ears were threshed manually. To maximize the implementation of the program, a sparse sowing method was used: the distance between plants in a row was up to 5 cm, between rows - 15-30 cm.
Phytopathological analysis of grain samples in the laboratory was used to isolate pathogens of the genus Fusarium into pure culture. The studied grain of hybrid populations was sterilized superficially by passing it over an alcohol flame and soaking in Domestos solution. The sterile grain was plated in Petri dishes on potato glucose agar (PGA) medium, ten seeds per ten dishes (100 seeds). Isolates were examined for 5-7 days, recording the presence or absence of microconidia. The final identification of pathogens was carried out by microscopic examination, taking into account morphological features, the presence or absence of chlamydospores. As a result of the studies, the most aggressive isolates of the fungal pathogen F. graminearum were isolated for the development of inoculum and the creation of an artificial infectious background in the field.
As you know, the development of winter wheat diseases is largely influenced by weather conditions, namely the sum of effective air temperatures and precipitation.
In 2021, during the spring-summer wheat growing season, the average monthly temperatures were higher than long-term data in March and June by 1.0 and 1.5°C, respectively, and in April and May, there was a decrease in air temperature compared to long-term data (-1.4, -0.8, respectively).The hydrothermal coefficient (HTC) for May, June, July of this year corresponded to 3.1, 2.7, 2.6, waterlogging contributed to the manifestation and intensity of the development of the pathogen of Fusarium head blight.
In 2022, the spring-summer growing season of wheat was characterized by sufficient moisture, although the amount of precipitation was 7-30 mm below the long-term average, with 349% of the long-term average precipitation falling in April alone. In terms of moisture availability, the reporting year was classified as a year with a mild drought (HTC = 0.9).
In April 2023, excessive moisture supply was noted, the excess of precipitation from the norm was 40.0 mm, and later during the period from May to June, a rather acute precipitation deficit was noted, especially in May - only 21.0 mm (the average long-term figure was 51.4 mm). The spring (April - June) period was not conducive to the development of the pathogen Fusarium head blight. Accordingly, the level of HTC was low: April - 0.89, May - 0.46, June - 0.67, and the intensity of damage by the pathogen of Fusarium head blight reached from 1.0 to 10.4% on an artificially infected background, and 1.0 to 3.1% on a natural background, which indicates a slight damage to winter wheat plants.
According to the results of the evaluation of F1 22 hybrid combinations established different degrees of phenotypic dominance, which determined the type of inheritance of traits, which in turn depended on parental components and weather conditions. The analysis of the results of the assessment of the degree of phenotypic dominance, inherited resistance to Fusarium graminearum in F1 hybrids of winter wheat from parental forms indicates that within this population the inheritance occurs according to the spectrum of types: heterosis (H), partially positive dominance (PPD), intermediate inheritance (II), partially negative inheritance (PNI) and negative superdominance (D).
Based on the degree of phenotypic dominance in 2021, it was found that among the hybrid combinations F1 13.63 % showed superdominance (H) against Fusarium graminearum. The highest heterosis was observed in three hybrid combinations: MIP Knyazhna / (Donskoy Prostor / Slavna) (hp = 2.4), MIP Vyshyvanka / (BILINMEVEN-49 / Natalka) (hp = 2.1), [(Mikon / ALMA) / Legenda Myronivska] / Podolyanka (hp = 1.3). Partial positive dominance (PPD) was found in 36.37% of hybrid combinations, it is worth noting the reciprocal combinations MIP Knyazhna ↔ (MV 20-88 / Smuglyanka) (hp = 0.6, 0.9, respectively) and MIP Vyshyvanka ↔ [(Mikon / ALMA) / Legenda Myronivska] (hp = 0.6, 0.7, respectively). And also in direct crosses - (Donskoy Prostor / Slavna) / MIP Vyshyvanka (hp = 0.9), MIP Knyazhna / (Mironovska rannostyhla / CATALON) (hp = 0.6) and others. The intermediate inheritance of the trait (II) was found in 13.63 % of hybrids, and depression (D) - 36.37 %.
In 2022, on the basis of resistance to the pathogen Fusarium head blight, heterosis was established in 31.81% of hybrid combinations F1. When the donor of resistance against Fusarium graminearum - Donskoy Prostor / Slavna - was involved in the crossing, heterosis was observed in hybrid combinations: (Donskoy Prostor / Slavna) / MIP Knyazhna (hp = 2.6), (Donskoy Prostor / Slavna) / MIP Vyshyvanka (hp = 2.1), Podolyanka / (Donskoy Prostor / Slavna (hp = 1.4).The reciprocal hybrid combination MIP Fortuna ↔ (Donskoy Prostor / Slavna) had a high level of positive dominance (hp = 1.3; 1.6, respectively), partial positive dominance (PPD) of the trait was found in 18.19 % of hybrids, intermediate inheritance - 45.46 %, depression (D) - 4.54 %.
In 2023, according to the degree of phenotypic dominance, hybrid combinations were distributed as follows: 22.73 % showed heterosis, 27.28 % - partially positive overdominance, 40.91 % - intermediate inheritance, 4.54 % - partial negative inheritance, 4.54 % - depression. Heterosis was revealed in hybrid combinations: MIP Knyazhna / (MV 20-88 / Smuglyanka) (hp = 6.0), MIP Vyshyvanka / (BILINMEVEN-49 / Natalka) (hp = 2.7), (Donskoy prostor / Slavna) / MIP Knyazhna (hp = 2.4), [(Mikon / ALMA) / Legenda Myronivska] / Podolyanka (hp = 2.2) and (Donskoy prostor / Slavna) / MIP Vyshyvanka (hp = 1.6). Partially positive dominance was found in the reciprocal hybrid combination Podolyanka ↔ (Donskoy Prostor / Slavna) (hp = 0.9; 0.6), in which the source of resistance to Fusarium head blight - Donskoy Prostor / Slavna - was involved in the cross.
For effective breeding work on the development of resistant genotypes against Fusarium graminearum, hybrid combinations with overdominance (heterosis) were of the greatest value. For the period 2021-2023, a high degree of dominance was found in 13.6% of hybrid combinations: MIP Vyshyvanka / (BILINMEVEN-49 / Natalka) (2.1 (ND), 1.2 (ND), 2.7 (ND), respectively), (Donskoy Prostor / Slavna) / MIP Vyshyvanka (0.9 (ND), 2.1 (ND), 1.6 (ND), respectively), [(Mikon / ALMA) / Legenda Myronivska] / Podolyanka (1.3 (ND), 0.4 (PU) 2,2 (ND), respectively) with the involvement of winter wheat varieties Podolyanka and MIP Vyshyvanka and donors of resistance against Fusarium pathogen (BILINMEVEN-49 / Natalka), (Donskoy Prostor / Slavna), [(Mikon / ALMA) / Legenda Myronivska].
