Spatiotemporal Distribution of Potato-Associated Alternaria Species in Wisconsin

Potato early blight caused by Alternaria solani and potato brown spot caused by Alternaria alternata are two common potato foliar diseases. Fungicide applications in Wisconsin target early blight with the expectation of managing brown spot simultaneously. However, distributions of the two pathogens over time and space have not been previously reported in Wisconsin. In this study, six potato fields in Wisconsin were systematically sampled during 2014 to 2017 to investigate the incidences of both pathogens; incidences of the pathogens were compared by location, timing, and year. Incidence of A. alternata had been recorded starting in late June in every field every year, whereas incidence of A. solani started later in some of the fields. At the end of each growing season throughout the four years, the highest incidence (100% most of the years) of A. solani was observed in a field in Plover, located in a concentrated potato production area of central Wisconsin, and a field in Arena, located in an isolated potato production area in southern Wisconsin. The highest incidence (100% every year) of A. alternata was observed in a field in Madison, an isolated potato field that was managed organically. Such distribution patterns could be a result of the different host ranges of the pathogens and abundance of inoculum in different geographic locations. In 2016, disease severity was correlated with the incidence of both pathogens (P < 0.0001 to P = 0.0299), but in 2017, disease severity was correlated with the incidence of A. solani in most of the fields (P < 0.0001 to P = 0.0799). These findings suggest that both Alternaria spp. are important for considering disease management strategies in central and southern Wisconsin.

Study on Post Harvest Losses in Potato in Different Storage Conditions

The study aimed to conduct a comparative study of three most common potato storage conditions (in-house store, in-basket store and cold store) and to find the most suitable storage condition for farmers. The experimental work involved post-harvest loss assessment and study of pattern of respiratory and reducing sugar level for sixty days storage period. Total loss was lowest (4.38%) for cold stored potatoes and highest (13.04%) for in-house stored potatoes. Reducing sugar accumulation was least (0.65%) and remained almost constant throughout study period for in-house stored potatoes. Reducing sugar accumulation gradually increased and was maximum (1.04%) for cold stored potatoes. Respiratory rate was least in cold stored potatoes which gradually decreased and reached 3.17mg CO2/kg/hr at the end of sixty days storage. Respiratory rate was maximum for in-basket stored potatoes which reached up to 6.55 mg CO2/kg/hr at the end of storage. Storage loss and respiratory rate are minimum for cold stored potatoes but showed high sugar accumulation. In-house storage do not suffer from excessive sugar accumulation but storage loss is maximum of all. In case of in-basket storage, besides being cheap and feasible, there is no problem of sugar accumulation and storage losses was also significantly lower than in-house storage.

CISGENIC BIOLISTIC TRANSFORMATION FOR OBTAINING NEW FORMS OF POTATOES WITH IMPROVED RESISTANCE TO LATE BLIGHT

This article presents the results of application of cisgenic biolistic transformation for the accelerated production of new forms of potato with increased resistance to late blight. The reason for late blight development is the parasitic organism Phytophthora infestans, belonging to oomycetes (pseudo-fungi), which infects valuable agricultural plants. In this study, with the aim of combating P. infestans, a number of experiments on the biolistic transformation of the most common potato varieties Aksor and Nevskiy were carried out in Kazakhstan. Two potato genes – Rpi-vnt1.1 and StREM1.3 – were selected as targets for introduction. Expression of the first gene should be activated, and the expression of the REMORIN1.3 gene should be suppressed. Rpi-vnt1.1 was under the control of Solanum tuberosum polyubiquitin gene promotor (Pat) and Arabidopsis thaliana polyubiquitin 5 gene terminator (ubq5). Knock-down double stranded RNA-hairpin gene construction for StREM1.3 silencing was under the control of Solanum tuberosum phytochrome B gene promotor (phyB) and Arabidopsis thaliana hot-shock protein 18.2 terminator (HSP18.2). Three series of biolistic transformation were carried out, as a result of which 636 regenerated plants of potato varieties Aksor and Nevskiy were obtained. DNA was extracted from the plant material of potato transformant plants in the quality and quantity suitable for PCR analysis for the presence of an insert. PCR analysis was carried out, revealing 52 plants carrying the VNT insert. StREM1.3 silencing gene construction was detected in plant lines by qPCR, based on comparative analysis of of gene expression level and revealed 6 lines with reliably lower StREM1.3 expression level in comparison with wild-type plants.

A modified droplet vitrification method for cryopreservation of shoot tips from in vitro potato plants

Collections of common potato maintained in the field genebanks suffer significant losses due to the impact of extreme environmental factors, diseases and pests. The solution of the problem of safe long-term preservation of common potato accessions is to create doublet in vitro and cryo-collections. Cryogenic collections are stored at ultra-low temperatures in cryobanks. Several methods of potato cryoconservation are known, of which the droplet vitrification method developed by B. Panis with colleagues in 2005 is the most widely used in genebanks. This paper provides a detailed description of the modified method of droplet vitrification, which is used for cryopreservation of apexes (shoot tips) of potato in vitro plants at the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR). The method modified at VIR includes the main steps of the original droplet-vitrification method developed by B. Panis and colleagues: 1) preparation of plant material, 2) isolation of shoot tips, 3) treatment of explants with cryoprotector solutions, 4) freezing/immersion in liquid nitrogen, 5) thawing, 6) post-cryogenic recovery and evaluation of viability and regeneration capacity. The modifications of stages 1, 2 and 6 proposed at VIR lead to a significant reduction in the duration of cryopreservation experiments in comparison with the original method of B. Panis. This paper presents the results of cryopreservation of modern potato cultivars and South American landraces which were obtained using the method of droplet vitrification as modified at VIR. The majority (76.7 %) of the studied accessions of cultivated potato were characterized by high rates of postcryogenic recovery (40–95 %) and 23.3 % of the samples had the values of postcryogenic regeneration from 20 to 39 %, which corresponds to the minimal permissible values for long-term storage in a cryobank. Currently the modified droplet-vitrification method is used for further expanding of the VIR potato cryocollection.

Metabolic Alterations in Male-Sterile Potato as Compared to Male-Fertile

The common potato, Solanum tuberosum L., is the fourth most important agricultural crop worldwide. Until recently, vegetative propagation by tubers has been the main method of potato cultivation. A shift of interest to sexual potato reproduction by true botanical seeds is due to the appearance of a new hybrid seed breeding strategy whose successful application for many crop species has been supported by male sterility. This investigation was focused on the study of differences in the metabolite profiles of anthers at the mature pollen stage from male-fertile and male-sterile genotypes of S. tuberosum. Application of gas chromatography coupled with a mass spectrometry method allowed detection of metabolic profiles for 192 compounds. Further data analysis with several libraries fully identified 75 metabolites; a similar amount was defined up to the classes. Metabolic profiles in the anthers of fertile genotypes were significantly distinguished from male-sterile ones by the accumulation of carbohydrates, while the anthers of sterile genotypes contained a higher amount of amino acids. In comparison with male-fertile plants, male-sterile genotypes had undeveloped pollen grain characters; i.e., smaller grain size, a thicker exine, “permanent tetrads” that failed to disintegrate into microspores, and the absence of pollen apertures that might be due to a disorder in the metabolism of carbohydrates and fatty acids.

Genetic Diversity of Potato virus Y in Potato Production Areas in Northeast China

In 2011–2014, ELISA or nucleic acid spot hybridization (NASH) testing for common potato viruses or Potato spindle tuber viroid (PSTVd) was performed on 500 leaf samples collected in potato fields in the northeast provinces Heilongjiang and Inner Mongolia, China. The results revealed that 38.4% (Heilongjiang) and 27.7% (Inner Mongolia) were positive for Potato virus Y (PVY). To unveil the strain composition and population structure of PVY in the region, the multiplex RT-PCR described by Chikh-Ali et al. was performed on all of the ELISA-PVY-positive samples. Of the 158 samples whose PVY strain scenarios could be determined, PVYNTN-NW-SYR-II and PVYN-Wi were the most abundant strains, occurring in 58.9 and 47.5% samples, followed by PVYNTN-NW-SYR-I (31.0%), PVYN:O (19.6%), Eu-PVYNTN (7.6%), NA-PVYN (1.3%), and PVYO (0.6%). In the 84 single-strain-infected samples, PVYN-Wi accounted for 41.7%, PVYNTN-NW-SYR-II for 40.5%, PVYNTN-NW-SYR-I for 14.3%, and PVYN:O and Eu-PVYNTN for 3.6% each. Seven isolates representing PVYNTN-NW-SYR-I (HLJ-6-1 and HLJ-9-4), PVYNTN-NW-SYR-II (INM-W-369-12 and SC-1-1-2), PVYN:O (HLJ-30-2), and PVYN-Wi (HLJ-BDH-2 and HLJ-C-429) were sequenced and analyzed molecularly. Whereas the sequence identities for isolates belonging to the same strain group were >98.5%, they fell for isolates belonging to different strain groups to 92.7–98.1% at the genome level and 96.1–98.4% at the polyprotein level. Interestingly, the exact location of the recombination events varied among isolates within a strain group. Phylogenetic analysis of all 42 full length PVY sequences from China indicated that most clustered to various recombinant groups, despite the fact that the PVY isolates were isolated from at least five host species. Pathological analysis of four isolates representing PVYN:O, PVYN-Wi, PVYNTN-NW-SYR-I, and PVYNTN-NW-SYR-II revealed that the PVYNTN-NW-SYR-II isolate incited the most severe symptoms on potato cultivar Kexin 13, followed by PVYNTN-NW-SYR-I, PVYN:O and PVYN-Wi. The PVYNTN-NW-SYR-I and PVYNTN-NW-SYR-II isolates also caused necrotic ringspots on the tubers of Kexin 13, indicating their ability to induce the potato tuber necrotic ringspot disease in potato.

The potato protection from major pests and diseases

Goal. To study the effectiveness of pesticides in protecting potato plantations from major pests and diseases. Methods. Comparative, analytical and field. Results. The data of technical and economic efficiency of pesticides against the main pests and diseases of potatoes are given. It was noted that the most effective against the complex of pests were drugs from the group of neocotinoids, and against diseases — fungicides of systemic and systemic contact action of various classes of chemical compounds. Conclusions. The most common potato diseases during the growing season of the crop were Alternaria and blight, the development of which in 2016—2017. amounted to 12.6—36.4% and 10.6—48.6%, respectively. Two spraying of potatoes with fungicides ensured technical effectiveness against Alternaria — 26.4—64.8%, against late blight — 24.3—53.9%. The main disease of potato tubers in 2017—2018 there was a common scab, the proportion of which in the control was 15.6%, and in the variants with the use of disinfectants — 5.4—8.6% of the total mass of the infected tubers. Dry Fusarium rot in the variants of the experiment was 2.5—2.8%, in the control — 9.3%. The number of bastards damaged by wireworms in the control was 7.2%, in the variants with the use of insecticidal and insecticidal and fungicidal disinfectants — 1.0—2.2%. It was established that the treatment of tubers with insecticidal and insecticide antifungal preparations against the Colorado potato beetle was effective for 40—50 days after planting potatoes, and further it is necessary to additionally spray it with insecticide.