Vladislav Ognjanov

Analysis and characterisation of phytochemicals in mulberry (Morus alba L.) fruits grown in Vojvodina, North Serbia

In this study, the polyphenolic profile of 11 Morus alba fruits grown in the Vojvodina region was investigated. Ultra high performance liquid chromatography (UHPLC) coupled with Linear Trap Quadrupole and OrbiTrap mass analyzer, and UHPLC coupled with a diode array detector and a triple-quadrupole mass spectrometer were used for the identification and quantification of the polyphenols, respectively. A total of 14 hydroxycinnamic acid esters, 13 flavonol glycosides, and 14 anthocyanins were identified in the extracts with different distributions and contents according to the sampling. The total phenolic content ranged from 43.84 to 326.29 mg GAE/100g frozen fruit. The radical scavenging capacity (50.18-86.79%), metal chelating ability (0.21-8.15%), ferric ion reducing power (0.03-38.45 μM ascorbic acid) and superoxide anion radical scavenging activity (16.53-62.83%) were assessed. The findings indicated that mulberry polyphenolics may act as potent superoxide anion radical scavengers and reducing agents.

Anatomical and biochemical studies of fruit development in peach

Abstract The development of fruit and seed tissues of Prunus persica L. Batsch cultivars ‘Springcrest’, ‘Redhaven’ and ‘Suncrest’ was studied in three consecutive years. Morphological and compositional changes in the embryo were related to the double sigmoid pattern of development in the pericarp. When the fruit of the early maturing cultivar, ‘Springcrest’, ripened the embryo had not developed to fill the ovule but it was morphologically complete and capable of normal germination under laboratory conditions. Only minor differences were noted in the rates of morphological differentiation of the three cultivars. However, when fruit ripened, the lipid content was about 7%, 38% and 59% of the seed dry matter in the early, midseason and late cultivars, respectively. The main reason for low field germination of early varieties appears to be a deficiency of energy reserve to ensure survival during low temperature after ripening.

Morphometric diversity in dwarf sour cherry germplasm in Serbia

Summary The search for growth-reducing rootstocks has produced selections of ‘Oblačinska’ sour cherry (Prunus cerasus L.) and European ground cherry (Prunus fruticosa Pall.). The methodological approach to germplasm collection was a compromise between a search for specific characters and random sampling of the population. On the principle of 19 variables in 27 accessions, this research brought valuable and diverse plant material into rootstock breeding. The vigour of adult trees on their own roots ranged from extremely weak, such as in selections of European ground cherry (SV1, SV3, SV4) and ‘Oblačinska’ sour cherry (OV31), to vigorous genotypes such as sour cherry (OV33 and OV34) and P. mahaleb. The natural habit of untrained trees varied from upright (e.g., SV7) to dropping (e.g., SV2). Internode lengths ranged from 1.36 cm (in SV8) to 4.11 cm (in SV4). Based on a PCA scatter-plot, six diverse sub-groups showing significant intra- and inter-species variability were distinguished. These findings were supported by high values of heritability, from 78.83 – 92.20%, implying the potential for successful selection of dwarfing genotypes based on their phenotypic characters in succeeding breeding activities. Preliminary field studies suggested that the ‘Oblačinska’ genotypes OV31 and OV32, as well as the European ground cherry genotypes SV1, SV2, and SV4, may represent rootstocks with the lowest vigour.

Anatomical Characteristics of Cherry Rootstocks as Possible Preselecting Tools for Prediction of Tree Vigor

An anatomical study of roots and stems of five self-rooted cherry rootstocks with different growth control potentials was performed to compare their structure and xylem anatomy. The aim was to correlate anatomical parameters with rootstock dwarfing potential and theoretical hydraulic conductance (kh), and to evaluate the potential application of anatomical characteristics in the preselection process for prediction of ultimate tree vigor. One of the mechanisms of water transport efficiency reduction in dwarfing rootstock stems is from the rootstock xylem anatomy. Anatomical parameters of ‘Gisela 5’ and ‘Mazzard’ were typical for dwarfing and vigorous rootstocks, respectively, and were thus suggested as reference rootstocks. Significantly greater vessel diameter and frequency were found in invigorating and dwarfing rootstocks, respectively. Higher kh was obtained in roots, compared to stems, due to significantly larger vascular elements. Dwarfing rootstocks had lower kh due to small vessel lumens and percentage and, to a lesser extent, because of low wood/cortex ratios or percentage of wood. A higher percentage of wood or xylem in cherry roots and stems was not always positively correlated with their conductivity and vigor. Thus, these parameters cannot be reliably used in prediction of the ultimate vigor, although this method was previously suggested for some other fruit tree species. The most reliable anatomical parameters for that purpose proved to be vessel frequency, vessel lumen area, and percentage of vessels on wood cross section. These characteristics could thus be an effective way to estimate dwarfing capacity and could be applied in rootstock selection and breeding programs.

Genetic resources in apple, pear and vineyard peach populations in former Yugoslavia

During the period 1988-90, several germplasm collecting trips were made to all republics of former Yugoslavia. A total of 56 old apple cultivars, many of which are represented in up to 5 types, 38 old pear cultivars and 367 genotypes of vineyard peaches were collected. The availability of so much genetic and genotypic wealth made it possible to start apple disease resistance breeding and peach cultivar and rootstock breeding programmes.

Tissue culture approaches to peach improvement

In-ovule embryo culture was used for obtaining seedlings from immature peach embryos 1-4 mm in length. Rapid micropropagation of Redhaven cultivar and B 52/2 vineyard peach selection was achieved by shoot tip proliferation. The two-stage rooting system, with a short auxin exposure followed by transfer to growth regulator-free half-strength basal media, proved to work much better than any other system published so far. Cotyledon regeneration was combined with Agrobacterium mediated genetic transformation. A clear difference in fluorescence between negative controls and the regenerants obtained after cotyledon inoculation with A. tumefaciens carrying the GUS gene was detected after 24 h indicating the production of chimeric peach plants.