The paper provides data on the use of the Malus sieboldii Rehd. as a genetic donor of economically valuable traits in breeding low-vigorous clonal apple rootstocks. The method of embryo culture is proposed as a way to increase the efficiency of distant crosses. The studies were carried out using seeds obtained in three combinations of crossing (M. sieboldii x Malysh Budagovskogo, M. sieboldii x 60-160, M. sieboldii x 76-3-6). As sterilizing agents when introduced into culture in vitro, we used industrial disinfectant «Belizna (Whiteness)», the sanitizer «Ecocid C» + «Belizna» and the sanitizer «BioPag C» + «Belizna». It was found that additional pretreatment with «Ecocid C» (1.0%) and "BioPag C" (0.4%) for 50 minutes before using the disinfectant «Belizna» contributes to the production of sterile explants up to 61.5% compared to the control. The best results were obtained when combine using «Ecocid C» (1.0%, 50 min.) and «Belizna» (50%, 5 min.). After 28 days, due to the low number of developing embryos, the method of dissection of a part of the cotyledons of hybrid seeds was used. As a result, up to 65.3% of hybrid plants were obtained, compared to 4.2% of the control.
For use in breeding work, the methods of complex accelerated cytological diagnosis of genotypes of fruit and berry crops with an altered ploidy level were optimized. The proposed diagnostic method was tested on polyploids of the genus Malus, Fragaria, Ribes, Rubus, rowan-pear hybrids and is recommended for wide scientific and practical application in the plant breeding and cytology. The effectiveness of this method is ensured by its availability and reliable statistical differences in accounting parameters. In a comprehensive cytological diagnosis of forms of fruit and berry crops with an increased level of ploidy, it is proposed to first study the morphoanatomical traits (sizes and proportions of stomatal guard cells, the number of chloroplasts in them, the diameter of pollen grains). This will significantly reduce the time of laboratory analysis and field assessment by deleting forms with unchanged indicator values.
The paper presents the results of identification of quantitative trait loci (QTL) of Dw1 and Dw2 involved in the control of dwarf growth in clonal apple rootstocks using the molecular markers. In total, 14 forms of rootstocks were analyzed. The microsatellite markers Hi01c04, Hi04a08, CH03a09 (for the Dw1 locus), MDP0000365711, and MDP0000243703 (for the Dw2 locus) were used in the study. Analysis of the results did not reveal a relationship between the presence of a marker and the manifestation of a sign. Of the three markers of the Dw1 locus, only Hi01c04 amplifies a fragment of the expected size of 120 bp. It was found in 9 forms of rootstocks (PB-4, 57-491, 83-1-15, M9, G16, 2-12-10, 2-9-102, 4-6-5 and 70-20-20). The Hi01c04 marker was identified in both dwarf and medium-sized forms. Of the two markers of the Dw2 locus, the desired fragment is amplified in MDP0000365711. It is typical for almost all genotypes. The exception is 83-1-15, 2-12-10 and 70-20-20, which have a null allele. To assess the genetic diversity of the Dw1 and Dw2 loci, 6 microsatellite sequences Hi01c04, Hi04a08, CH03a09, CH02d08, MDP0000365711, and MDP0000243703 were used. In 14 studied samples, 29 allelic variants ranging in size from 102 bp. up to 170 bp were identified. The number of alleles per locus varied from 1 (for the MDP0000365711 locus) to 7 (for the Hi04a08 locus). No rare alleles were identified. All alleles were observed more than three times. Based on the analysis of SSR spectra, a dendrogram reflecting the similarity of the genotypes under study was built.
The analysis of the content of pigments in the stems of clonal apple rootstocks bred by Michurinsky State Agrarian University showed a high content of anthocyanins (more than 200 mg/100 g for rootstock 54-118). When determining the qualitative composition, it was revealed that anthocyanins in the stems of the rootstocks are represented by three groups, while there are differences in the shape of the rootstocks. As a source of pigment production, it is necessary to select rootstocks with a high endogenous synthesis of anthocyanins (i.e. red-leaved forms 54-118, 57-491, 98-7-77, etc.), during the cultivation of which, in addition to the main product—detachable rooted cuttings-one can additionally receive from 3 to 10 kg of anthocyanin dyes from 1 hectare of mother plant.
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