Citrus collections from extreme growing regions can be an important source of tolerant germplasms for the breeding of cold-tolerant varieties. However, the efficient utilization of these germplasms requires their genetic background information. Thus, efficient marker systems are necessary for the characterization and identification of valuable accessions. In this study, the efficiency of 36 SCoT markers and 60 InDel markers were evaluated as part of the broad citrus collection of the Western Caucasus. The interspecific and intraspecific genetic diversity and genetic structures were analyzed for 172 accessions, including 31 species and sets of the locally derived cultivars. Single markers, such as SCoT18 (0.84), SCoT20 (0.93), SCoT23 (0.87), SCoT31 (0.88), SCoT36 (0.87) и LG 1-4 (0.94), LG 4-3 (0.86), LG 7-11 (0.98), and LG 8-10 (0.83), showed a high discriminating power, indicating the good applicability of these markers to assess intraspecific diversity of the genus Citrus. Overall, SCoT markers showed a higher level of polymorphism than InDel markers. According to analysis of population structure, SCoT and InDel markers showed K = 9 and K = 5 genetic clusters, respectively. The lowest levels of genetic admixtures and diversity were observed among the locally derived satsumas and lemons. The highest level of genetic admixtures was observed in the lime group. Phylogenetic relationships indicated a high level of interspecific genetic diversity but a low level of intraspecific diversity in locally derived satsumas and lemons. The results provide new insight into the origin of citrus germplasms and their distribution in colder regions. Furthermore, they are important for implementing conservation measures, controlling genetic erosion, developing breeding strategies, and improving breeding efficiency.

Diospyros lotus is the one of the most frost-tolerant species in the Diospyros genera, used as a rootstock for colder regions. Natural populations of D. lotus have a fragmented character of distribution in the Northwestern Caucasus, one of the coldest regions of Diospyros cultivation. To predict the behavior of D. lotus populations in an extreme environment, it is necessary to investigate the intraspecific genetic diversity and phenotypic variability of populations in the colder regions. In this study, we analyzed five geographically distant populations of D. lotus according to 33 morphological leaf traits, and the most informative traits were established, namely, leaf length, leaf width, leaf index (leaf to length ratio) and the length of the fourth veins. Additionally, we evaluated the intraspecific genetic diversity of D. lotus using ISSR and SCoT markers and proposed a new parameter for the evaluation of genetic polymorphism among populations, in order to eliminate the effect of sample number. This new parameter is the relative genetic polymorphism, which is the ratio of polymorphism to the number of samples. Based on morphological and genetic data, the northernmost population from Shkhafit was phenotypically and genetically distant from the other populations. The correspondence between several morphological traits (leaf width, leaf length and first to fifth right vein angles) and several marker bands (SCoT5, SCoT7, SCoT30: 800–1500 bp; ISSR13, ISSR14, ISSR880: 500–1000 bp) were observed for the Shkhafit population. Unique SCoT and ISSR fragments can be used as markers for breeding purposes. The results provide a better understanding of adaptive mechanisms in D. lotus in extreme environments and will be important for the further expansion of the cultivation area for persimmon in colder regions.

The article analyzes the collection of citrus crops of the Federal Research Center "Subtropical Scientific Center of the Russian Academy of Sciences" (FITC SNC RAS) in Sochi. The bioresource collection is kept alive in the field and in a container culture for varieties; the collection is represented by the genetic and ecological-geographical diversity of C. reticulate Blan varieties. var unshiu.Tan., C. limon Burm., C. sinensis Osb., C. paradisi Macf., C. maxima Burm., C. medica L. and other species and relatives introduced from Japan, America, China, Italy, Spain, Nicaragua, Abkhazia. The collection is constantly updated with both introducers and new varieties and promising hybrids bred in the Center. Lemon and tangerine groups are widely represented. 19 sources of economically valuable traits that are included in the breeding process have been identified and described from the collection. Citrus reticulata Blanco is of great importance for the humid subtropics of Russia as the most winter-hardy species. Breeding work is being carried out, which is aimed at breeding early-maturing, short-term, stunted forms of mandarin. Ten varieties of mandarin have been created: Sochi 23, Pioneer 80, Krasnodar, Sugar, Black Sea, Millennium 1, Millennium 2, it is most adapted to extreme growing conditions. Because of hybridization, 21 promising forms of mandarin were identified, which are of interest for further breeding work. Large-fruited hybrids 98-1; 99-2; 99-4 were noted, the average yield of which was 3.4 kg /day, these forms are late-ripening (II decade of November). Forms 2-2; 01-4; 01-04; 97-3; 2-5; 2-5 they are characterized by early maturity (II decade of October), stunting and stable yields of 2.6 and 3.0 kg/day. Samples for ornamental gardening are presented: C. ? bergamia, C. ? bergamia var. Melarosa, S. Lemon "Del Brasil", C. ? limetta, C. ? limonelloides, C. verrucosa Tan., C. hystrix DC., as well as two forms:202 (Fortunella margarita?C. reticulata); 78 (Fortunella Margarita?C. reticulata).

Currently, the preservation of the biodiversity of cultivated plants and species of natural flora is an urgent task for scientific institutions. At the same time, biotechnological methods in the preservation of the plant gene pool are of particular importance. The article presents the results of research on the maintenance and study of the in vitro collection of subtropical fruit, berry, and flower-and-ornamental crops, as well as species of natural flora included in the Red Books of the Russian Federation and the Krasnodar Territory. The work on creating an in vitro plant collection began at the Subtropical Scientific Center of the Russian Academy of Sciences in 2010. Currently, the collection includes more than 113 plant species, which belong to 39 species and 83 varieties from 22 families. The most representative collections are from the following families: Amaryllidaceae J.St.-Hil., Asteraceae Giseke, Orchidaceae Juss., and Rosaceae Juss. The majority of the in vitro collection (73 %) consists of flower crops, while 14.7 % consists of endangered and rare species of natural flora, and the remaining 12.3 % consists of subtropical fruit and berry crops culture. The purpose of our research is to study and preserve the plant collection in vitro. The factors influencing the timing of subcultivation and the duration of deposit have been identified. It has been established that the content of osmotic substances (mannitol, sorbitol) and ABA in the nutrient medium, as well as low air temperature (+7…+15 ℃) and low illumination (500-1000 lux) affect the duration of plant cultivation. The genetic stability of plant material stored in the in vitro collection was assessed, and it was found that the ISSR and IRAP primers used in the study provided stable and reliable data that confirmed the similarity between cultivars and plants from their natural habitats. Keywords: plant collection, in vitro conditions, subtropical crops, species, osmotic substances, deposition Acknowledgements: The research was part of State Assignment FRC SSC RAS FGRW-024-0008. № 1023110900223-6-4.1.1 and FGRW-2024-0003, № 124022000093-1.