Anatoly Zh. Semenov

The potato is one of the most important food crops in the world. Improving the efficiency of potato breeding is of great importance for solving the global food problem. Today, researchers distinguish between six potato cytoplasm types: A, M, P, T, W, D. In the current study, the complete chloroplast genomes of Solanum tuberosum accessions with five out of the six major cytoplasmic genome types were sequenced (T-, W-, D-, A-, and P-genomes). A comparative analysis of the plastomes in potato accessions with different cytoplasm types was carried out for the first time. The time of origin of the different cytoplasm types was estimated. The presence of two main groups of chloroplast genomes among cultivated potato was confirmed. Based on the phylogenetic analysis of the complete plastome sequences, five main evolutionary branches of chloroplast genomes can be distinguished within the Petota section. Samples with A- and P- cytoplasm formed isolated and distant groups within a large and polymorphic group of samples with M-type cytoplasm, suggesting that A and P genomes arose independently. The findings suggest that the diversity of the T-genome in S. tuberosum Group Tuberosum could be initially low due to a bottle neck already existing at the origin of the Chilean clade. Differences in the rbcL gene sequence may be one of the factors causing differences in economically important traits in species with A and T-type cytoplasm. The data obtained will contribute to the development of methods for molecular marking of cytoplasm types and increase knowledge about the evolution and diversity of potato.

The wide occurrence of potato genotypes characterized by male sterility considerably complicates the realization of breeding programs. Therefore, male fertility in potato germplasm requires assessment as an important task. In the fresh study, 57 breeding lines from the Russian Potato Research Center and 85 cultivars of different origins underwent acetocarmine staining and in vitro germination assessment. With acetocarmine staining, 22 samples exhibited with tetrad sterility. In the remaining 120 samples, stained pollens vary from 0% to 88.7%, and germination varies from 0% to 19.4%. The pollen fertility assessment data obtained through acetocarmine staining and in vitro germination differed significantly. In the studied potato accessions, acetocarmine staining provided 18.3% sterile samples, while 50.7% by in vitro germination. The highest stained pollens (>80%) appeared in five potato accessions, i.e., 3004-7 (88.7%), 3000-32 (86.5%), 21.32-1 (81.8%), 17.32-1 (80.3%), and cultivar Garant (86.8%). In most potato accessions, the colored pollen grains ranged from 40% to 70%. The maximum percent of pollen germination occurred in the sample, 21.32-1 (19.4%). However, seven accessions (21.32-1, 18.5-17, 20.3-6, 20.33-8, and cultivars Edison, Queen Anne, and Garant) showed more than 10% pollen germination. During the growing season of 2022, the weather was hotter and drier compared with past long-term data, which could affect a decrease in the ability of pollens to germinate. The obtained results on male fertility will help in the study of the genetic control of pollen fertility and a further improvement in the breeding of Solanum tuberosum L.

The throughput and single-base resolution of RNA-Sequencing (RNA-Seq) have contributed to a dramatic change in diagnostics of viruses and other plant pathogens. A transcriptome represents all RNA molecules, including the coding mRNAs as well as the noncoding rRNA, tRNA, etc. A distinct advantage of RNA-Seq is that cDNA fragments are directly sequenced and the reads can be compared to available reference genome sequences. This approach allows the simultaneous and hypothesis-free identification of all pathogens in the plant. We conducted surveys for potato (Solanum tuberosum L.) -associated phytopathogenic bacteria in 56 original and GenBank RNA-seq data sets for potato breeding material. Bacteria of genera Pseudomonas, Burkholderia, Ralstonia, Xanthomonas, Agrobacterium, and species of family Enterobacteriaceae were most frequently detected in RNA sets from the studied plants. RNA-seq reads identified as Xanthomonas spp. were within X. vesicatoria, and some other species. Xanthomonas spp. covered up to 9,1% of all reads and included the major clades of these bacteria known as pathogens of solanaceous crops, but potato. Bacteria of genus Xanthomonas infect different plant species under artificial inoculation, suggesting that they are shared among wild plants and crops. Our studies indicated that a larger number of solanaceous plants can be occupied by specific Xanthomonas pathovars as endophytes or latent pathogens. Revealing bacteria distribution in the plant breeding material using RNA-seq data improves our knowledge on the ecology of plant pathogens.

Potatoes contain antioxidants such as flavonoids, carotenoids and ascorbic acid. High level consumption worldwide makes potato a valuable source of phytonutrients. Developing new potato varieties with high nutritional value in combination with resistance to pathogens is an important task. In this study, 25 interspecific potato hybrids with resistance to Synchytrium endobioticum, common scab, silver scab, rhizoctonia, nematodes and PVY were evaluated for total phenolics, total flavonoids, total carotenoids, ascorbic acid contents and antioxidant activity. The identification of the dominant allele related with yellow flesh color at the Chy locus was also performed by the specific CAPS marker. Total protein content was detected and ranged from 8.19 ± 0.59 to 30.17 ± 4.56 mg/g dry weight (DW). Total starch and total carbohydrate contents were in the range of 9.0–21.0% and 73.21 ± 20.94–676.36 ± 195.28, respectively. Total phenolic content of hybrids varied from 8.45 to 82.75 mg/100 g, and total flavonoids content—from 0.64 to 9.67 mg/100 g DW. It is possible to distinguish samples with high protein and carbohydrate contents, high level of substances with antioxidant activity and characterized by resistance to pathogens. Quality evaluation has shown that some of the samples have a high potential for processing and chip production in combination with high eating qualities. These samples can be used in breeding programs to develope varieties resistant to pathogens and with high nutritional value.