De novo SNP calling reveals the candidate genes regulating days to flowering through interspecies GWAS of Amaranthus genus

Amaranths serve as pseudo cereals and also as traditional leafy vegetables worldwide. In addition to high vigor and richness in nutrients, drought and salinity tolerance of amaranth makes it a promising vegetable to acclimatize to the effects of global climate change. The World Vegetable Center genebank conserves about 1,000 amaranth accessions and various agronomic properties of these accessions were recorded during seed regeneration over decades. In this study, we verified the taxonomic annotation of the germplasm based on a 15K SNP set. Besides, in the assumption that the yield components of grain amaranths are different from those of leaf amaranths, we observed that grain amaranths presented larger inflorescences and earlier flowering than leaf amaranths. Dual-purpose amaranth showed larger leaves than leaf amaranths and later flowering than grain amaranths, which seemed reasonable because farmers can harvest more leaves during the prolonged vegetable stage, which also provides recovery time to enrich grain production. Considering frequent interspecies hybridization among grain amaranth complex, we proposed an interspecies GWAS for days to flowering, identifying a AGL20/SOC1 homolog. Meanwhile, another GWAS using only A. tricolor accessions revealed six candidate genes homologous to lba1, bri1, sgs1 and fca. These homologous genes were involved in the regulation of flowering time in Arabidopsis. This study revealed the usefulness of genotypes for species demarcation in the genus Amaranthus and the potential of interspecies GWAS to detect QTLs across different species, opening up the possibility of targeted introduction of specific genetic variants into different Amaranthus species.

Betula pendula Roth. natural regeneration in forest-steppe zone of Tatarstan Republic

A direct dependence of the birch coppice regeneration on the diameter of the tree trunk, felling age, forest growth conditions, seed regeneration, soil and climatic conditions and the degree of soil mineralization has been revealed. It was found that after the dying of a 30-year-old birch due to a drought in 2010, coppice shoots appeared in 10 % of the trees on the studied area. The reasons for vegetative regeneration have been determined, which mainly occurs by the degree of thickness in trees with a trunk diameter of up to 22 cm, or by the category of state in dead wood (70 % of the total number of coppice). The absence of seed birch undergrowth in drying birch plantations was found as a result of the tremendous soil ramping and the predominance of small-leaved lime, aspen undergrowth, Norway maple of seed origin, and seed origin oak, which requires tending. For successful birch seed regeneration under favorable climatic conditions, it is recommended to carry out soil mineralization of at least 50 % of the total area. When carrying out vegetative propagation, it is necessary to cut birch no older than 40 years, and in case of useful properties loss in birch forests over 71 years old in protective forests, we recommend the use of clear cutting but not selective cutting. Keywords: natural renewal, hanging birch, undergrowth, logging, Republic of Tatarstan

CURRENT POTENTIAL RANGE AND DISTRIBUTION OF GENTIANOPSIS BARBATA (FROEL.) MA IN THE SOUTHERN URALS AND ADJACENT AREAS

The aim of the study is to analyse the distribution and the potential range of Gentianopsis barbata (Froel.) Ma in the Southern Urals. Maxent software was used for modeling. BIOCLIM (CHELSA) climate variables as well as the variables of a digital elevation model were used as predictors for modeling. The results of the potential range modeling have shown that despite being confined to habitats with a high moisture regime, high habitat suitability for this species is found mainly in areas with a fairly arid climate. At the same time, the main habitats of G. barbata are connected with slightly saline wet meadows located in floodplains of steppe rivers, along lake shores and mainly used as hayfields. Thus, moisture variability associated with interannual fluctuations in temperature and precipitation can weaken competition with other species and create suitable conditions for seed regeneration of this annual and biennial species.

The features of the biennial shoot systems of Ulmus glabra Huds. characteristic of the crown in the virginal age state

The morphological features of crowns were studied on the material of individuals of U. glabra of seed regeneration in the gaps of decaying three-hundred-year-old oak forests. We collected data on all crown shoots of five trees of young virginal age (from 10 to 18 years). The principal component method was used twice: first on the model tree to characterize features of the shoots biennial systems under the study, then to reveal ontogenetic and structural features of the crown organization of five virginal trees. Using the method of shoots biennial systems extraction allowed us to form a set of qualitative and quantitative characters reflecting crown structure properties of virginal trees of U. glabra, namely: properties of axes branching order, ontogenetic age of shoots in the crown, crown density, individual properties of tree crown structure.

Seed Regeneration of Buxus colchica Pojark. under the Conditions of Epiphytotics of Boxwood Forests

In response to expansion of Cydalima perspectalis Walker, 1859, mass scale drying of Buxus colchica Pojark. resulted in succession of forest communities of the Western Caucasus in 2014–2017. Changes in illumination of the forest low storeys were conducive to intensive growth of such herbaceous plants as Symphytum grandiflorum DC., Asarum intermedium (C. A. Mey. ex Ledeb.) Grossh., Festuca drymeja Mert. & W.D.J. Koch, Allium ursinum L., etc. and Ruscus colchicus Yeo, Geranium robertianum L., Rubus anatolicus Focke, Hedera colchica (K. Koch) K. Koch in the undergrowth. The ground vegetation with total projective cover up to 100 % was formed. Under current conditions the total number of B. colchica seedlings 2–15 cm high is only 10–320 pcs/ha on the southern macroslope and 5–87 pcs/ha on the northern macroslope. It is hundreds and thousands of times less as it was before boxwood forests extinction. The research purpose was to determine the factors effecting seed regeneration of B. colchica in the Western Caucasus under the conditions of succession caused by C. perspectalis expansion and further epiphytotics of boxwood forests. We carried out the studies on the southern and northern macroslopes of the Western Caucasus in the basins of the Khosta, Kurdzhips, and Tsitsa rivers in 2018–2019. The number of B. colchica seedlings was determined by their complete enumeration within 66 sampling plots; the area of each plot comprised 400 m2. When revealing the factors which effect seed regeneration of B. colchica, we analyzed 17 landscape and phytocenotic parameters: altitude above sea level; exposure and slope inclination; crown density of upper storey; parameters of undergrowth, main species stands, and dead boxwood; total projective cover of undergrowth and herbage. The principal factor preventing development of B. colchica seedlings is growthinhibition due to the herb-shrub storey. The total projective cover of undergrowth and herbage are the most important predictors for the number of B. colchica seedlings on the sampling plots. For the mentioned parameters we revealed the maximum regression coefficients b* at the significance level p < 0.05: –0.589 and –0.478 for the southern macroslope, and – 0.667 and –0.954 for the northern macroslope. The maximum projective cover of undergrowth in forest areas with boxwood regeneration is 50 % for both macroslopes. The maximum acceptable herbage cover is 15 % in the basin of the Khosta river, and 40 % in the basins of the Tsitsa and Kurdzhips rivers. Shading from the side of the forest upper storey suppresses growth of ground vegetation, and also prevents the development of B. colchica seedlings. Therefore the crown density, within the complex of factors, has no direct effect on the parameters of seed regeneration of B. colchica. In case of further intensive growth of the herb-shrub storey in forest phytocenoses, natural boxwood forests regeneration is highly improbable in the Western Caucasus. Artificial removal of undergrowth and herbage in forest areas will facilitate seed regeneration of the species. The research results are the basis for further monitoring of the regeneration processes of boxwood forests or their possible aboriginal change in the region.

Common ash (Fraxinus excelsior L.) in Ukrainian forests and its successful natural regeneration

The natural distribution area of common ash (Fraxinus excelsior L.) in the forests of Europe and Ukraine has been determined through the analysis of scientific works of Ukrainian and foreign researchers. According to the reference materials on the current state of Ukrainian forests (25 administrative regions), it is established that ash forests cover an area of about 150,000 ha or 2.4% of the total area of the country’s forests. Among them, common ash stands account for almost 87% or 130,000 ha; the rest are stands of introduced ash species, namely F. pennsylvanica Marsh., F. americana L., and F. lanceolata Borkh. The average age of ash stands is 59 years. Only 6.4% (8,300 ha) of the total area of ash forests is covered by pure ash stands, and the remaining area (93.6% or 121,700 ha) are mixed ones. It is revealed that the optimal natural and climatic conditions for the emergence, preservation and successful growth of natural regeneration of ash trees are fresh and moist fertile sites (rich in minerals) with well-drained soils, the light of at least 5–6% of that on an open space, and without abundant live ground cover. The highest number of seed regeneration of ash, about 7,000–8,000 stems ha−1 on average, was found under the canopy of mixed (ash share in the composition was 10 to 20% by stock) old (over 100 years old) stands with a relative density of stocking of 0.7–0.8. Promoting the natural seed regeneration of ash trees can be an effective way of increasing the sustainability of such stands and will ensure their preservation in the forests of Ukraine and in deciduous forests of Europe as a whole.

A RECORD OF RHODODENDRON SCHLIPPENBACHII (ERICACEAE) IN THE VICINITY OF NAKHODKA CITY (PRIMORYE TERRITORY)

A new location of the rare plant – Rhododendron schlippenbachii, listed in the Red Data Book of Russia, in the vicinity of Nakhodka City is reported. It is the most eastern point of this species in the Primorye Territory. This species was previously known only in the Khasansky district. On test area of 160 m2, with geographic coordinates N42.7849 °, E132.8204 °, in the oak forest with an undergrowth of Lespedeza bicolor at the top of the west slope registered 10 of generative plants. The plants are well developed (their sizes are 2,5 m in height, the shrub contain 3–6 skeletal branches) and bloom profusely. Found seed regeneration.