Efectele genetice implicate în răspunsul grăului comun la filtratul de cultură Drechslera sorokiniana (SACC.) subram

Helminthosporiosis caused by the fungus Drechslera sorokiniana (Sacc.) causes significant crop and quality losses to Triticum aestivum L. in agroecological conditions with extreme humidity. Increasing the resistance is considered the most cost-effective and sustainable approach to disease control. The aim of this study was to determine the genetic effects involved in the inheritance of resistance, using the ge-netic model of character reproduction in descendants of wheat. Generations F1, F2, BCP1 and BCP2, de-scended from the mutual crossing of the parents Basarabeanca / Moldova 30 and Moldova 30 / Moldova 3 (P1 and P2) were evaluated for the response of callus characters to the action of D. sorokiniana culture filtrate on the medium Murashige Skoog. Fungal metabolites have decreased the effects of gene actions and epistatic interactions, but also their variance. The phenomenon corresponds to the decrease of callus indices. A great importance for the heredity of the character of the surface of the callus manifested the epistatic effects of additive-dominant (ad) type. In the case of callus biomass comparable to the mean val-ues were the a actions, but also the ad and dd epistatic effects. The predominant involvement of epistatic effects indicates the need for resistance selections to helminthosporiosis in late generations of wheat.

Inheritance of resistance of spring barley to Erysiphe graminis f. sp. hordei in F1 and variability in F2 in the conditions of the Right-Bank Forest-Steppe of Ukraine

The nature of the inheritance of resistance to Erysiphe graminis f. sp. hordei in the crosses of genotypes of spring barley in F1 and transgressive variability in F2 populations are investigated. Inheritance of the trait of resistance to Erysiphe graminis f. sp. hordei in F1, by hybridization of genotypes of spring barley with known genes of resistance to Erysiphe graminis f. sp. hordei in European varieties Eunova (mlo11) and Barke (mlo9), which are located on chromosome 1H, was positively dominated. Inheritance of the F1 trait in Aspen (mlo11) and Adonis (mlo9) cultivars was partially positive. The influence of parental pairs for hybridization on the indicators of the degree of phenotypic dominance, hypothetical and true heterosis was established. Resistance to Erysiphe graminis f. sp. hordei in F1 hybrids was observed heterosis (positive dominance) in fve hybrid combinations (hp = 1.1–1.9 %): Barke/Badoryi, Barke/Sanktrum, Parnas/Rostentsii, Badoryi/ Barke, Eunova/Zvershennia. Hypothetical heterosis (Ht) in F1 was observed in 13 of 16 hybrids (from +2.8 % to +97.6 %). A positive value of true heterosis (Htb) in F1 was observed in 15 hybrids out of 16 (from +1.9 % to +98.8 %). Inheritance of the trait of resistance to Erysiphe graminis f. sp. hordei in all studied hybrids was influenced by the cytoplasm of the mother plant, except for the hybrid Eunova / Triangel, where the influence of the nuclear apparatus was detected. Hybrids were found in the F 2 population with high resistance to Erysiphe graminis f. sp. hordei, which exceeded the parental components, which indicates a signifcant shaping process and the possibility of selection on the basis of the studied trait. The degree of positive transgression ranged from 16.0 % to 73.0 % in hybrids Aspen / Skarlet, Adonis / Vanja, Barke / Badoryi, Barke / Sanktrum, Eunova / Triangel and Eunova / Zvershennia, where highly resistant varieties were used for the mother form. The combinations in which the frequency of transgression was observed in more than 50.0 % of plants are hybrids: Eunova / Triangel, Barke / Sanktrum, Eunova / Zvershennia, Parnas / Rostentsii and Barke / Badoryi. Key words: spring barley, resistance, Erysiphe graminis f. sp. hordei, combinations of crossing, inheritance, F1, true and hypothetical heterosis, degree of phenotypic dominance, F 2, degree and frequency of transgressions.

Search for the parent material of spring soft wheat resistant to septoria tritici blotch and analysis of the trait inheritance

In 2017-2020 in the conditions of Kirov region there were studied 143 varieties, 115 perspective lines and 28 hybrids of the first generation of spring soft wheat according to the degree of resistance to septoria tritici blotch against the background of the natural development of infection. It has been established that development of the disease significantly increased with a decrease in air temperature during the «seedling-tillering» phase (r = -0.83…-0.96) and an increase in the amount of precipitation during «shooting» phase (r = +0.87…+0.90). Resistance to septoria tritici blotch was shown by 16.1 % collection samples. A significant (r = -0.83) decrease in yield by an average of 19 % in susceptible samples compared to resistant ones was revealed. The greatest breeding and immunological value were represented by the varieties of Russian selection: Tobolskaya, Tyumenskaya 29, Moskovskaya 35 and МIS, among which the early variety MIS was tolerant to septoria tritici blotch. Thirteen lines resistant to septoria tritici blotch were identified from the new breeding material. The varieties selected for resistance to septoria tritici blotch were used in hybridization. In F1 hybrids domination and overdomination in the inheritance of resistance to septoria tritici blotch prevailed, as well as weight of 1000 grains and yield per 1 m2. Among them, 8 hybrids F1 with the highest values of the dominance indices were identified. It has been established, that inheritance of resistance to septoria tritici blotch, weight of 1000 grains and yield of hybrids F1 occurs both in the maternal and paternal lines. The greatest immunological effect was obtained when using the varieties Daria (Russia) and Epos (Germany). The most productive hybrids were the variety Daria, taken as both a maternal and paternal form, as well as when using the Egisar 29 (Russia) variety as a maternal form.

Leaf-to-Whole Plant Spread Bioassay for Pepper and Ralstonia solanacearum Interaction Determines Inheritance of Resistance to Bacterial Wilt for Further Breeding

Bacterial wilt (BW) disease from Ralstonia solanacearum is a serious disease and causes severe yield losses in chili peppers worldwide. Resistant cultivar breeding is the most effective in controlling BW. Thus, a simple and reliable evaluation method is required to assess disease severity and to investigate the inheritance of resistance for further breeding programs. Here, we developed a reliable leaf-to-whole plant spread bioassay for evaluating BW disease and then, using this, determined the inheritance of resistance to R. solanacearum in peppers. Capsicum annuum ‘MC4′ displayed a completely resistant response with fewer disease symptoms, a low level of bacterial cell growth, and significant up-regulations of defense genes in infected leaves compared to those in susceptible ‘Subicho’. We also observed the spreading of wilt symptoms from the leaves to the whole susceptible plant, which denotes the normal BW wilt symptoms, similar to the drenching method. Through this, we optimized the evaluation method of the resistance to BW. Additionally, we performed genetic analysis for resistance inheritance. The parents, F1 and 90 F2 progenies, were evaluated, and the two major complementary genes involved in the BW resistance trait were confirmed. These could provide an accurate evaluation to improve resistant pepper breeding efficiency against BW.