Word from the Editor-in-Chief.

The most important requirement to be met by promising varieties is adaptability, i. e., the ability to resist environmental factors that reduce productivity and product quality. To create such varieties, a constant search for sources and donors of consistently manifested economically valuable traits is required. For this purpose, agroecological adaptedness and its components were assessed for 42 fiber flax specimens with respect to the most important features, namely the yield of flax fiber and its number. Significant differences (P_0.05) between the specimens concerning these characteristics were established. The average fiber yield in the study was 87.9 g/m². In 23 specimens, the yield exceeded the average value. The maximum fiber yield was recorded for the Russian specimens ‘Tonus’ (130.6 g/m²) and ‘Nord’ (128.3 g/m²). These specimens had the highest long fiber yield (42.7 and 40.4 g/m²), respectively.

The average number of the scutched long fiber in the study was 10.1. This value exceeded the average one in 24 specimens. The Belarusian varieties ‘Alej’ and ‘Mogilyovskij’ had the maximum number of the scutched long fiber for three years (11.3), and also maximum indices (1.2) concerning the number of the scutched long fiber.

A high degree of responsiveness to improved environmental conditions (Ri) expressed as an increase in the long fiber yield was demonstrated by the varieties ‘Alej’, ‘Tonus’, ‘Surskij’, ‘Cezar’ (Ri = 39.4%, 35.4%, 32.9%, 32.2% respectively), and that expressed in the number of the long scutched fiber was displayed by specimens ‘Sal'do’ × ‘Rodnik’ (Ri=19.8%), ‘Surskij’, ‘Venus’, VIR-14, and VIR-12, (Ri=16.5%).

The specimens Vera (D_i= –7.14%), Batist (D_i= –7.69%), and VIR-15 (D_i= –10.64%) were characterized by low responsiveness to unfavorable factors in respect of the long fiber yield. Such conditions did not cause a decrease in the number of the long scutched fiber in the specimens ‘Dobrynya’, ‘Diplomat’, ‘Polisky 4’, VIR-13, ‘L'vovskіj 8’, ‘Esman’, and ‘Miander’ (D_i,%=0.0). The specimens ‘Tonus’ (D_i= –44.3%), ‘Cezar’ (D_i= –43.8%), ‘Lino de fibra’ (D_i= –42.1%), China 1 TMR1919 (D_i= –41.8%), Gorizont (D_i=–40,9%) were highly responsive to stress factors in terms of fiber yield. A sharp decrease in the number of the long scutched fiber under unfavorable factors was observed for specimens ‘Kaliakra’, VIR-17, ‘Venus’, and ‘Sursky’ (D_i= –27,7%).

Thirteen specimens received high ratings of agroecological adaptedness in terms of the yield of fibre and its number. The Belarusian variety ‘Alej’, Lithuanian specimens B-192, B-168 and the Russian ‘Dobrynya’ were included in the first group with a high degree of agroecological adaptedness with respect to the studied characteristics.

The creation of F₁ hybrids combining high productivity, valuable biochemical composition and resistance to biotic and abiotic environmental factors is an urgent area of work with Brassicaceae Burnett.

To create a homogeneous, genetically stable source material in breeding, in vitro cell technologies are used to increase the number of doubled haploids used as source material for creating new cultivars and hybrids.

Brassica rapa L. includes annual and biennial crops. Using traditional breeding methods, it takes at least 8-10 years to produce selectively valuable F₁ hybrids of B. rapa. With the help of modern technology for producing doubled haploids in the isolated microspore culture, this process can be shortened to 2-3 years.

B. rapa is one of the Brassica crops least suitable for microspore in vitro cultivation; most of the studied accessions are self-incompatible and retain a high degree of heterozygosity and heterogeneity. To date, there is no effective protocol that is equally suitable for the induction of embryogenesis in different B. rapa accessions.

Embryogenesis in an isolated microspore culture of the Brassica plants is subject to the timing of microspore development, pre-treatment of buds, composition of the nutrient medium (macro- and microelements, iron sources, organic additives, carbohydrates, growth regulators) and cultivation conditions. In addition, this process strongly depends on the genotype of the individual plant.

This review presents the main achievements in the development of protocols for obtaining doubled haploids of B. rapa. Particular attention is paid to the factors influencing the efficiency of haploid production in the isolated microspore culture.

The genome-substituted synthetic form Avrodes (AABBSS) was used for transferring resistance to yellow rust (Puccinia striiformis f. sp. tritici Eriks.) from Aegilops speltoides Tausch, (2n = 14) to bread wheat. The study involved 24 introgressive lines of bread wheat obtained using the Avrodes form. Yellow rust resistant lines P07-L.02, P07-L.1, P07-L.17, P07-L.43, P07-L.19, AS12-88, AS12-06, AS12-07, AS12- 51, Asp81-21, Asp63-21, Asp053-21, Asp04-21, Asp022-19, Asp023-19 and Asp029-20 were selected and can be used as new donors of disease resistance. The use of differential chromosome staining (C-banding) and fluorescence in situ hybridization (FISH) identified the genetic material of Ae. speltoides transmitted in the form of 5S(5D) chromosome substitution and translocations of T5BS.5BL-5SL, T2DL.2DS-2SS, T5D, as well as translocation of T1BL.1RS from Secale cereale L. The work revealed that the lines with single translocations of T1BL.1RS and T5BS.5BL-5SL were susceptible to yellow rust, while the lines in which the T2DL.2DS-2SS translocation and 5S(5D) substitutions were identified, as well as the lines with translocations of T1BL.1RS, T2DL.2DS-2SS and T5D showed resistance to the disease. Presumably, the selected introgression lines, obtained by means of crosses with Avrodes, may carry new genes or loci for yellow rust resistance.

Background. The creation of varieties with genetic resistance to fungal pathogens is one of the most important directions in strawberry breeding. A promising direction of accelerated selection of valuable specimens is molecular screening for the presence in their genotype of diagnostic DNA markers, linked to target genes of agrobiological traits.

Objectives of the work were determination of the allelic state of the Rca2 (resistance to anthracnose) and Rpf1 (resistance to red stele root rot) genes in selected strawberry forms to identify genotypes resistant to Colletotrichum acutatum Simmonds and Phytophthora fragariae var. fragariae Hickman.

Material and methods. The object of research was breeding forms of strawberries of intervarietal hybrid origin. As a result of 22 crossing combinations, 61 selection forms were obtained, in which the allelic composition of resistance genes was studied. The Rca2 anthracnose resistance allele was identified by means of the STS-Rca2_240 marker. The Rpf1 red stele root rot resistance allele was identified with the help of SCAR-R1A marker.

Results. At least one of the two genes was identified in 20 selected strawberry forms (32.8%). The STS-Rca2_240 marker was identified in 15 strawberry seedlings (22.9%) from six hybrid combinations ‘Vicoda’ × ‘Roxana’, ‘Florence’ × ‘Faith’, ‘Asia’ × ‘Aprica’, ‘San Andreas’ × ‘Monterey’, ‘Alisa’ × ‘Quicky’, ‘Quicky’ × ‘Olympia’). The SCAR-R1A marker was identified in five strawberry seedlings (8.2%) from four hybrid combinations (‘Privlekatelnaya’ × ‘Bylinnaya’, ‘Feyerverk’ × ‘Bylinnaya’, ‘Bylinnaya’ × ‘Feyerverk’, ‘Bylinnaya’ × ‘Olimpiyskaya nadezhda’). It has been established that all strawberry selected forms with identified marker fragments for resistance genes are characterized by a heterozygous combination of alleles.

Conclusions. Promising sources of resistance alleles are strawberry selected forms: 2/1-24, 2/1-34 (‘Quicky’ × ‘Olympia’), 3/9-5 (‘Florence’ × ‘Faith’), 3/12-2, 3/12- 9 (‘Alisa’ × ‘Quicky’), 4/7-10, 4/7-19, 4/7-20 (‘Asia’ × ‘Aprica’), 5/2-26, 5/2-32 (‘San Andreas’ × ‘Monterey’), 9/ 1-11, 9/1-12, 9/1-13, 9/1-32, 9/1-37 ‘Vicoda’ × ‘Roxana’) in case of Rca2 gene; 72-24, 72-71 (Privlekatelnaya × Bylinnaya), 69-29 (‘Feyerverk’ × ‘Bylinnaya’), 62-41 (‘Bylinnaya’ × ‘Feyerverk’), 61-15 (‘Bylinnaya’ × ‘Olimpiyskaya nadezhda’) in case of Rpf1 gene.