Inhibition of Three Potato Pathogens by Phenazine-Producing Pseudomonas spp. Is Associated with Multiple Biocontrol-Related Traits

Plant-beneficial phenazine-producing Pseudomonas spp. are effective biocontrol agents, thanks to the broad-spectrum antibiotic activity of the phenazine antibiotics they produce. These bacteria have received considerable attention over the last 20 years, but most studies have focused only on the ability of a few genotypes to inhibit the growth of a limited number of plant pathogens.

Synthetic gel structures in soils for sustainable potato farming

Anti-pathogenic protection of potatoes remains one of the most pressing problems of sustainable agronomy and plant protection. For this purpose, we propose to use a new type of synthetic hydrogels filled with amphiphilic recipients (dispersed peat, humates) and modern plant protection products. We assumed that the introduction of swollen gel structures into the rhizosphere of potatoes will allow us: to optimize the water supply and productivity of potatoes; to protect the fertile layer and potato tubers from the main pathogens; to fix modern plant protection products in the rhizosphere, keeping them from leaching and entering the environment. Preliminary laboratory experiments tested the anti-microbial activity of gel structures, as well as their water retention, dispersity and hydraulic conductivity with subsequent computer modeling of the water exchange and root uptake in the system of “soil-gel-potato”. Field trials were carried out in humid (European Russia) and arid (Uzbekistan) conditions under the atmospheric precipitation and irrigation on different soils and potato varieties with instrumental monitoring of environment, potato growth and quality. All experimental results confirmed the high efficiency of water-accumulative and plant protective synthetic gel structures. Their usage sufficiently (up to 6–15 t/hct) increases the potato yield with 1.3–2 times water saving, complete retention of agrochemicals in the rizosphere, and its actually total protection against major potato pathogens, including late blight (Phytophthora infestans).

Pan-genome analysis identifies intersecting roles for Pseudomonas specialized metabolites in potato pathogen inhibition

Agricultural soil harbors a diverse microbiome that can form beneficial relationships with plants, including the inhibition of plant pathogens. Pseudomonas are one of the most abundant bacterial genera in the soil and rhizosphere and play important roles in promoting plant growth and preventing disease. However, the genetic determinants of this beneficial activity are only partially understood, especially in relation to specialized metabolite production. Here, we genetically and phenotypically characterize the Pseudomonas fluorescens population in commercial potato field soils and identify strong correlations between specialized metabolite biosynthetic pathways and antagonism of the potato pathogens Streptomyces scabies and Phytophthora infestans. Genetic and chemical analyses identified hydrogen cyanide and cyclic lipopeptides as key specialized metabolites associated with S. scabies inhibition. We show that a single potato field contains a hugely diverse and dynamic population of Pseudomonas bacteria, whose capacity to produce specialized metabolites is shaped both by plant colonization and defined environmental inputs.

Planting a Problem: Examining the Spread of Seed-Borne Potato Virus Y

Potato virus Y (PVY) is among the most economically impactful potato pathogens, yet the spread of PVY from infected seed potatoes within commercial potato fields has not been adequately studied. Test lots containing various seed-borne PVY levels were created by mixing different proportions of seed pieces from healthy and infected tubers drawn from the same seed source. These seed lots were planted in commercial potato fields near the Teton Seed Potato Management Area from 2010 to 2012. Regression analyses on data from these test plots produced models of the in-season spread of PVY originating from infected seed. Conventional ordinary least squares techniques were supplemented with the use of quantile regression; the resulting models indicate the significance of seed-borne PVY on end-of-season infection levels and highlight the need of seed potato buyers to review postharvest testing results.

Potato Pathogens in Russia’s Regions: An Instrumental Survey with the Use of Real-Time PCR/RT-PCR in Matrix Format

Viral and bacterial diseases of potato cause significant yield loss worldwide. The current data on the occurrence of these diseases in Russia do not provide comprehensive understanding of the phytosanitary situation. Diagnostic systems based on disposable stationary open qPCR micromatrices intended for the detection of eight viral and seven bacterial/oomycetal potato diseases have been used for wide-scale screening of target pathogens to estimate their occurrence in 11 regions of Russia and to assess suitability of the technology for high-throughput diagnostics under conditions of field laboratories. Analysis of 1025 leaf and 725 tuber samples confirmed the earlier reported data on the dominance of potato viruses Y, S, and M in most regions of European Russia, as well as relatively high incidences of Clavibacter michiganensis subsp. sepedonicus, Pectobacterium atrosepticum, and P. carotovorum subsp. carotovorum, and provided detailed information on the phytosanitary status of selected regions and geographical spread of individual pathogens. Information on the occurrence of mixed infections, including their composition, was the first data set of this kind for Russia. The study is the first large-scale screening of a wide range of potato pathogens conducted in network mode using unified methodology and standardized qPCR micromatrices. The data represent valuable information for plant pathologists and potato producers and indicate the high potential of the combined use of matrix PCR technology and network approaches to data collection and analysis with the view to rapidly and accurately assess the prevalence of certain pathogens, as well as the phytosanitary state of large territories.

Negative Effects of Chemicals Used Against Potato Pathogens on the Natural Environment

Purpose. This study focused on the analysis of chemicals most often used against potato pathogens and their negative impact on both water and soil ecosystems, as well as the search for alternative solutions. This aspect is extremely important since the quality and quantity of the crop depend mainly on the appearance of diseases on the plantations and postharvest storage conditions. Most often, the fight against pathogens is carried out with the help of fungicides. They, in turn, have a negative impact on water and soil systems, which affects the level of fertility and the quality of farmed products. Results. The analysis showed a negative effects of fungicides on the soil and water ecosystems. According to the reported results, the most dangerous are propamocarb hydrochloride, mancozeb, fluazinam and famoxate. Noteworthy, 30% of the chemicals presented in this review are extremely toxic, 38% are moderately toxic, and 17% are toxic. It was found that the recurring usage of the same fungicides causes the adaptation of pathogens to the active substances while their replacement with other chemicals generates additional costs. The research indicates the necessity of modifying the current protection strategy by eliminating the most dangerous chemical compounds for nature and supplementing the protection program with environmentally safe biopreparations. A new strategy was proposed to fight potato pathogens based on the components obtained from domestic plants of the high biological activity potential (e.g. Curcuma longa, Allium sativum). An innovative approach to plant protection is the use of natural, effective and safe technologies to reduce or even eliminate the traditional chemical preparations. Conclusions. To prevent further degradation of the environment, the presented chemicals must be replaced by effective natural substances showing the antimicrobial activity. The prevention of further degradation of the environment caused by the development of agriculture is extremely important, because the quality and yield of crops depend on the soil quality, and the quality of crops affects human health.

Preserved Microarrays for Simultaneous Detection and Identification of Six Fungal Potato Pathogens with the Use of Real-Time PCR in Matrix Format

Fungal diseases of plants are of great economic importance causing 70–80% of crop losses associated with microbial plant pathogens. Advanced on-site disease diagnostics is very important to maximize crop productivity. In this study, diagnostic systems have been developed for simultaneous detection and identification of six fungal pathogens using 48-well microarrays (micromatrices) for qPCR. All oligonucleotide sets were tested for their specificity using 59 strains of target and non-target species. Detection limit of the developed test systems varied from 0.6 to 43.5 pg of DNA depending on target species with reproducibility within 0.3−0.7% (standard deviation). Diagnostic efficiency of test systems with stabilized and freeze-dried PCR master-mixes did not significantly differ from that of freshly prepared microarrays, though detection limit increased. Validation of test systems on 30 field samples of potato plants showed perfect correspondence with the results of morphological identification of pathogens. Due to the simplicity of the analysis and the automated data interpretation, the developed microarrays have good potential for on-site use by technician-level personnel, as well as for high-throughput monitoring of fungal potato pathogens.