O. V. Mochalova: Polyploid Cherries

Horticulture and viticulture. 2017;(5):19-22. (In Russ.)
Polygenomic pentaploid and hexaploid hybrids of steppe cherry for gametes breeding
O. V. Mochalova
The aim of the work, conducted in the climate conditions of Altai region on the basis of field and gamete selections, was to identify the polygenomic forms of cherry with a complex of reproductive and economically valuable features for subsequent breeding crossings. In 2013-2017 by the using of remote hybridization, field selection and cytological chromosomes number counting methods, original selective pentaploid and hexaploid interspecific steppe cherry hybrids, producing unreduced gametes, carrying a complex of economically valuable features (winter hardiness, resistance to coccomicosis, fast yielding, setting fruits of high quality) have been identifi ed to include them in intervalent crossings and in the primary variety testing. Pollen fertility of the selective forms depends on the level of ploidy and on the individual characteristics of the specifi c genotype. Pollen fertility and viability of pentaploids were varied from 0 up to 58 %, and from 0 up to17 % respectively. Pentaploid 323-09-3 is characterized by male sterility and can only be used as a maternal form. Pollen quality on hexaploids was higher in comparison with pentaploids: the fertility was from 43,3 up to 64,7 %, the viability was from 12,3 up to 32,7 %. A description of reproductive and economically signifi cant characteristics for four pentaploids and for two hexaploids from the gene pool of the Federal Altai Scientifi c Centre of Agro-BioTechnologies is given.

Contemporary Horticulture. 2018;(3):47-55.
Peculiarities of microsporogenesis in hexaploid hybrids of steppe cherry (Prunus fruticosa Pall.).
O. V. Mochalova
The use of hexaploids is a new methodical direction in the breeding of cherry, allowing the reviving of correct meiosis passing and the restoration of sterile hybrids productivity, for increasing of genetic diversity in seed progeny. The purpose of the scientific research was to reveal the cytological peculiarities of microsporogenesis and the quality of pollen for spontaneous steppe cherry hexaploids, located in the Altai gene pool (FSBSI FASCA), to determine their reproductive and breeding potential. The individual characteristics of microsporogenesis, the formation of microspores sporades and the morphophysiology of mature pollen grains for the single hybrid from crossing steppe cherry (Prunus fruticosa Pall.) with sour cherry (P. cerasus L.) and for two hybrids from crossing steppe cherry with Manchurian cherry (P. maackii Rupr.) were estimated. It was revealed that the average number of meiocytes with disturbances was equal 50-60% from their total number and depends on the genotype. Weather conditions of the concrete year have a significant impact on the course of microsporogenesis. As an individual event is a combination of “universal” anomalies (associated with multivariate chromosomal conjugation and dysfunction of the spindle of cell division) and cytomixis. During chromosomal conjugation all hybrids form polyvalents, bivalents and univalents in an individual ratio also. In chromosomal plates of the metaphase of the second division the chromosomal number usually equals n=3x±5 chromosomes. Only for the Bh 8-83-46 hybrid 0.8% of haploid (n=8) and the same number of diploid (n=16) chromosomal sets were found. The number of euploid chromosomal plates for the studied forms was found in the range of 35.8-46.7% from their total number. Tetrads of microspores with correct morphology were found at the level of 28.2-68.4%. Dyads and triads of microspores were also discovered (in the aggregate amount from 0.2 to 20.6 %). The fertility of pollen grains for hexaploids was within 58-82%, the viability of pollen was 10-35%. All hybrids form multi-aperture (4 or more growth pores) pollen grains in the amount of 7-88% from the total number of fertile ones. The good pollen quality implies the successful use of all studied hexaploids in intervalent crosses to obtain genetic and phenotypic diversity in the gene pool of steppe cherry.

Pomiculture and small frits culture in Russia 55: 38-45 (2018) (In Russian)
Genetic-breeding ways of conservation and explanation of Steppe Cherry (Prunus fruticosa Pall.) Genofund: Comprehensive Approach
O. V. Mochalova, I. V. Ershova, T. V. Plaksina, T. E. Boyandina, D. A. Gusev
At present, on the background of deterioration of the ecological situation, an increase in the frequency of dangerous mushroom epiphytoty and climate change, the Russian cherry gene pool does not meet contemporary production requirements. The accumulated and preserved Altai gene pool of the steppe cherry can be considered one of the most significant in the Russian Federation. It has a long history of creation and currently involves 6 wild-growing species, over 100 accessions and 4,070 hybrids from 255 families. Genetic sources of valuable breeding features were revealed, including 18 that act as the genetic producers of unreduced gametes. The collections involving 63 natural and 350 amitotic polyploids, created through in vitro culture, are constantly replenished and maintained. In the long term, the steppe cherry culture is expected to move on a new hexaploid level (2n = 48).To maintain and expand the existing original gene pool and for its successful use in breeding, a complex methodical approach is needed. The authors of the article proposed an improved scheme of the breeding process, including: the attraction of new wild-growing East Asian genetic sources (P. incisa Thunb., P. canescens Bois., P. serrulata Lindl.), remote hybridization, polyploidy, gamete selection, in vitro culture (embryoculture, micropropagation, mutagenesis), selection according to biochemical parameters for fruit quality. For the accelerated analysis of the data, an electronic database of chemical parameters of cherry fruit was created.

Agrarian Bulletin of the 190(11): 44-51 (Nov 2019)
New genetic sources for breeding of Prunus L. species on polyploid level
O. V. Mochalova, Dmitriy Gusev
This research is aimed at studying of the chromosomal number distribution within the new, in vitro cultured, amitotic clonal lines of Prunus species, at comparing of the fertility and size of pollen for triploid and hexaploid amitotic clones and at identifying of new genetic sources and their subsequent use in breeding. Methods. The standard cytological and statistical methods were used in this scientific work. Results. The regularities of induced polyploids output both from the initial number of chromosomes and from the origin and individual characteristics of the original genotypes were established. For amitotic hexaploid genotypes of hybrid cherry, high pollen quality was discovered at the level of 81,8–92,6 % of fertility (in triploids the 4,6–18,8 % of such pollen was found), therefore, the studied 4 clonal cherry genotypes (12-1-1T2, 12-1-1T6, 12-1-2T3, 12-1-2Tv) are recommended for breeding of resistant to fungal diseases varieties. No significant differences were found in the diameter of fertile pollen (46.3–47.8 Um) between cherry amitotic triploids and hexaploids. Therefore, in all likelihood, fertile pollen in triploids carries an unreduced triploid set of chromosomes. Prime scientific novelty. A completely new and original selection material for the genus Prunus L. – polyploid hybrids of P. fruticosa Pall. with rare East-Asiatic cherry species P. serrulata Lindl., P. canescens Bois., P. incisa. Thunb. were studied. The arguments in favor of a positive breeding prospect for the transfer of new cherries varieties to the hexaploid level (2n = 48), including an in vitro culture method of chromosome number doubling for the sterile triploid interspecific hybrids, have been obtained. The first created tetraploid (2n = 32) amitotic clonal lines of microcherry P. pumila L. must be tested in crosses with thorns and hybrids of thorns.

BIO Web Conf. Vol. 24, (2020)
International Conferences “Plant Diversity: Status, Trends, Conservation Concept” 2020
Siberian gene pool of steppe cherry polyploids (Prunus fruticosa Pall.): cytomorphological estimation and prospects for breeding
Olga V. Mochalova
Federal Altai Scientific Center for Agrobiotechnology (FASCA), 656910, Barnaul, Russia
The first spontaneous cherry polyploids were detected in the Altai gene pool of Russia and inside of the interspecific hybrids of Prunus fruticosa Pall. only. To date, polyploid genotypes with a complex of economically valuable traits and of various origins has preserved in the collection of FASCA. Collection includes: 1) F1 of spontaneous origin; 2) F2 obtained from hybridization of the first spontaneous hexaploid genotypes; 3) hybrids induced in vitro. These hybrids have a genetic origin from steppe cherry crossings with P. cerasus L., P. maackii Rupr., P. serrulata Lindl., P. canescens Bois., P. incisa Thumb., etc. Hexaploid amitotic clone lines were obtained by of 0.1% trifluralin treatment. The cellular mechanism of polyploids occurrence is the male and female unreduced gametes functioning. The study of microsporogenesis in 38 hybrids has revealed the 17 genetic producers of unreduced male gametes. According to the ploidy level of seedlings, the 8 sources of unreduced female gametes were selected. The morphophysiological characteristics of mature pollen were studied and the patterns for the preliminary selection of polyploids were revealed. The main strategy for the cherry breeding in the 21th century is the creation of polygenome hybrids with increased adaptation and high fruit quality.