Taxonomic structure of tissue endophytic bacterial microbiome in clonal apple rootstock grown on sod-podzolic soils with variant properties

The taxonomic structure of tissue endophytic bacterial microbiome was comparatively studied in microplants (undifferentiated explant callus tissues, passage 25) and 5-year clonal apple rootstocks 57-490 and 54-118 cultured from corresponding tissues (passage 1) on sod-podzolic soils with variant granulometry, chemical, physical and physicochemical properties. Proteobacteria (91.6 %) predominated in vitro tissues among other endophytic bacterial phyla in rootstock 57-490, while Proteobacteria (52.5 %) and Firmicutes (47.4 %) — in rootstock 54-118. The endophytic Firmicutes ratio vs. in vitro tissues decreases (0.7-2.0 %) in roots and more severely (0-0.2 %) in leaves. Endophytic Actinobacteriota are revealed in 11.7 % in roots of the study rootstock in heavy loam soil, whilst in medium loam their ratio drops to 2.74.1 % in roots and 0.1-0.2 % in leaves. The phylogenetic diversity indices estimation for main endophytic bacterial phyla in apple rootstock tissue recovers their essentially lower diversity and evenness in culture endosphere (Shannon index 0.42-1.00) vs. open soil roots (1.34-2.08). The leaves Shannon index is typically low (0.06-0.13) indicating poor diversity and evenness of the main endophytic bacterial phyla.

Promising clonal apple rootstocks in Crimea

Современная экономика диктует необходимость быстрой и эффективной окупаемости затрат, вложенных в производство продукции садоводства, что требует интенсификации отрасли. Одним из путей решения поставленных задач является закладка садов на клоновых подвоях, обеспечивающих высокое, стабильное плодоношение, с плодами отменных вкусовых качеств, подбор новых подвоев, приспособленных к условиям Крыма и не уступающих по комплексу хозяйственно-биологических свойств районированным в регионе. В статье освещены результаты многолетнего изучения 14 клоновых подвоев в сочетании с двумя сортами яблони. Определена сила роста изучаемых привойно-подвойных комбинаций в почвенно-климатических условиях Предгорного Крыма. Комбинации сортов Аскольда и Ренет Симиренко с подвоями ЕМ-IX, КД 4, КД 5 по показателям параметров кроны относятся к слаборослой группе. Деревья на К 104 по силе роста занимают положение промежуточное между ЕМ-IX и ММ-106, но имеют хорошо развитую корневую систему и компактную форму кроны. Выделенные комбинации рано вступают в плодоношение (на 2-3-й год). Средний урожай таких насаждений равен 24,4-30,6 т/га. Отобранные подвои обладают большим биологическим потенциалом и эффективными хозяйственно-биологическими свойствами, и представляют интерес для южного садоводства. Modern economy necessitates quick and effective return of costs invested in the horticultural production, which requires the intensification of the industry. One of the ways to solve the assigned tasks is to establish gardens on clonal rootstocks ensuring high and consistent fruiting with crops of excellent palatability traits, selection of new rootstocks adapted to the conditions of Crimea and not inferior in terms of the range of economic and biological properties to those released in the region. This paper highlights the results of long-term study of 14 clonal rootstocks in combinations with two apple varieties. The growth power of the studied scion-rootstock combinations in the soil and weather conditions of the Piedmont Crimea was determined. Combinations of ‘Ascolda’ and ‘Renet Simirenko’ varieties with rootstocks EM-IX, KD 4, and KD 5 in terms of crown parameter values belong to a dwarf group. Trees on K 104 are intermediate between EM-IX and MM-106 in terms of growth power, but have a well-developed root system and a compact crown shape. The above mentioned combinations enter into fruiting very early (on the 2nd-3d year). The average yield of such plantations is 24.4- 30.6 t/ha. The selected rootstocks are of great biological potential and effective economic and biological properties, so they are promising for southern horticulture.

Identification of dwarfism loci Dw1 and Dw2 in clonal apple rootstocks using molecular markers

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 suitability of using waste from the production of planting material for apple trees to obtain natural anthocyanin dyes

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.

Digitalization of the breeding process of clonal apple rootstocks

The paper shows the results of many years of experience in breeding low-growing clonal apple rootstocks at Michurinsky State Agrarian University. The relevance of the introduction of digital technologies at all stages of the breeding process from the formation of a data bank for the selection of parental pairs to research in the garden of the competitive study of rootstock-varietal combinations is shown. The apparatus and software for specific research stages are proposed. It is found that the developed methodology and digital technologies make it possible to significantly reduce the time of the breeding process, achieve the intended results faster and more efficiently and most fully reveal the genetic potential of breeding achievements.

Alleviation of Nematode-Mediated Apple Replant Disease by Pre-Cultivation of Tagetes

Apple replant disease (ARD) is a severe problem in orchards and tree nurseries caused by yet unknown soil biota that accumulate over replanting cycles. This study tested the contribution of nematodes to ARD, and cultivation of Tagetes as a control option. In a pot experiment, Tagetes patula or Tagetes tenuifolia were grown in ARD soil, incorporated or removed. Nematodes extracted from untreated ARD soil and washed on 20-µm sieves induced ARD symptoms when inoculated to apple plantlets growing in a sterile substrate. In contrast, nematodes from Tagetes treated ARD soil did not reduce root growth compared to uninoculated plants, irrespective of Tagetes species and incorporation. In plots of five apple tree nurseries or orchards, either Tagetes or grass was grown on ARD soil. Nematodes extracted from the grass plots and inoculated to apple plantlets significantly reduced plant growth compared to nematodes from Tagetes plots for all five farms. Apple rootstocks showed overall a significantly higher increase in shoot base diameter when grown on Tagetes-treated plots compared to grass plots, while this effect differed among farms. Plant-parasitic nematodes were too low in abundance to explain plant damage. In conclusion, Tagetes alleviated ARD by changing the nematode community in soil.

Alleviation of Nematode-Mediated Apple Replant Disease by Pre-Cultivation of Tagetes

Apple replant disease (ARD) is a severe problem in orchards and tree nurseries caused by yet unknown soil biota that accumulate over replanting cycles. This study tested the contribution of nematodes to ARD, and cultivation of Tagetes as a control option. In a pot experiment, Tagetes patula or Tagetes tenuifolia were grown in ARD soil, incorporated or removed. Nematodes extracted from untreated ARD soil and washed on 20 µm-sieves induced ARD symptoms when inoculated to apple saplings growing in a sterile substrate. In contrast, nematodes from Tagetes treated ARD soil did not reduce root growth compared to uninoculated plants, irrespective of Tagetes species and incorporation. In plots of five apple tree nurseries or orchards, either Tagetes or grass was grown on ARD soil. Nematodes extracted from the grass plots and inoculated to apple saplings significantly reduced plant growth compared to nematodes from Tagetes plots for all five farms. Apple rootstocks showed overall a significantly higher increase in shoot base diameter when grown on Tagetes-treated plots compared to grass plots, while this effect differed among farms. Plant-parasitic nematodes were too low in abundance to explain plant damage. In conclusion, the free-living nematodes involved in ARD can be controlled by Tagetes.

Biotechnology for obtaining virus-free apple planting stocks

The review describes the successive stages of work on the production of virus-free apple planting stocks using biotechnology methods. Compositions of nutrient media, duration and temperature regime of plant material treatment, and other details for all stages of cryopreservation (cryotherapy), chemotherapy, detection of viruses are presented, methods of in vitro initiation, micropropagation, in vitro rooting and adaptation of plant material to the soil substrate are discussed. Virus-free collection of Malus domestica Borkh. and M. sieversii Ledeb. M. Roem. is preserved by in vitro culture and cold storage (+4 °C). Cryopreservation of shoot tips of apple historic cultivars and wild forms in liquid nitrogen at -196° will preserve this valuable material for a long time and, if necessary, can be used in breeding. Virus-free apple rootstocks and cultivars will be available to provide planting material of a super-elite class for local nurseries and in general will promote the development of the domestic nursery.

Effects of Interval Flooding Stress on Physiological Characteristics of Apple Leaves

As a result of the continuous global warming in recent years, the average annual number of rain days in China has been on the decline, while the number of rainstorm days has gradually increased. These conditions make it extremely easy to form a waterlogging environment, which has an adverse impact on plant growth and development. In many apple-producing areas in China, apples are subject to severe flooding during planting. In this study, two-year-old apple rootstock M9T337 was used to explore the effects of interval water stress on the morphological and physiological parameters of apple leaves. The purpose was to determine the plant’s adaptability to waterlogged environments and provide theoretical reference for management and maintenance after waterlogging. The results showed that the effect on flooded (T2) on apple stock was greater than that of waterlogged (T1), Short-term (7 d) waterlogging (T1) did not affect the growth of seedlings but was conducive to the accumulation of dry matter. Furthermore, the initial stress was be imprinted on the plants, which could directly affect their response to later stress. The results of principal component analysis (PCA) revealed that PC1, PC2, and PC3 explained 26.92%, 17.46%, and 13.03% of the physiological changes under water stress, respectively. By calculating the weight of each indicator, we concluded that high-frequency resistance r, relative chlorophyll content (SPAD) and maximum photochemical efficiency Fv/Fm are important parameters for apple rootstocks affected by water stress.