Pseudomonas lactucae sp. nov., a pathogen causing bacterial rot of lettuce in Japan

Two phytopathogenic bacteria, MAFF 301380T and MAFF 301381, isolated from rot lesions of lettuce (Lactuca sativa L. var. capitata L.) in Japan, were characterized using a polyphasic approach. The cells were Gram-reaction-negative, aerobic, non-spore-forming, rod-shaped and motile with one to three polar flagella. Analysis of the 16S rRNA gene sequences showed that the strains belong to the genus Pseudomonas and are closely related to Pseudomonas cedrina subsp. cedrina CFML 96-198T (99.72 %), Pseudomonas cedrina subsp. fulgida P515/12T (99.65 %), Pseudomonas gessardii DSM 17152T (99.51 %), Pseudomonas synxantha DSM 18928T (99.44 %), Pseudomonas libanensis CIP 105460T (99.44 %) and Pseudomonas lactis DSM 29167T (99.44 %). The genomic DNA G+C content was 60.4 mol% and the major fatty acids consisted of summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c), C16 : 0 and summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c). Phylogenetic analysis using the rpoD gene sequences and phylogenomic analyses based on the whole genome sequences demonstrated that the strains are members of the Pseudomonas fluorescens subgroup but formed a monophyletic and robust clade separated from their closest relatives. The average nucleotide identity and digital DNA–DNA hybridization values between the strains and their closely related species were 88.65 % or less and 36.3 % or less, respectively. The strains could be distinguished from their closest relatives by phenotypic characteristics, pathogenicity towards lettuce and whole-cell MALDI-TOF MS profiles. The evidence presented in this study supports the classification of the strains as representing a novel Pseudomonas species, for which we propose the name Pseudomonas lactucae sp. nov., with the type strain MAFF 301380T (=ICMP 23838T).

Genetic sources of resistance to root rots chicory

Relevance. One of the significant problems in the technology of obtaining root chicory is the protection of root vegetables from the defeat of root rots. The most common lesions of root vegetables chicory various pathogenic species of fungi causing phomosis (Phoma rostrupii Sacc.), gray rot (Botrytis cinerea (R.) Fr.J), wet bacterial rot (Erwinia carotovora (Jones) Holt.). An important place in solving this problem is the breeding of new varieties that are resistant to major diseases and adapted to the conditions of cultivation in the soil-climatic conditions of the chicory-seeding zone. This requires, first of all, to determine the range of donor varieties of the sign of resistance to root rots, both during the growing of culture, and during long-term storage.Material and methods. In 2018-2020, studies were carried out to assess gene sources of different ecological and geographical origin (including against a provocative background) in the Non-Black Earth Zone of the Russian Federation and to isolate donors of resistance to root rot from them. Research on the Rostov Vegetable experimental station on chicory.Results. Studies have shown that the defeat of root vegetables chicory root rots genetic sources were very different from each other, so Harpachi, Luxor did not affect the. root rots neither on the usual nor on provocative backgrounds.

Вacterial rot of tomatoes when grown in a protected ground

The specific conditions of the protected ground, the almost constant tomato culture without substitution of the substrate, the elevated temperature and humidity lead to the accumulation of a large number of pathogens of bacterial diseases, which limit the increase in yield of this crop. The aim of the work was to characterize the symptoms, determine the etiology of wet rot of tomatoes for growing in protected ground and propose measures to control the pathogen. The study was conducted by standard microbiological and phytopathological methods. The pathogenic properties of the isolates were studied on vegetative tomato plants using a suspension of bacterial cells with a titer of 107 CFU/ml. It was established that the defeat of tomato plants with soft bacterial rot in closed ground conditions prevails in the second half of the growing season. The development of the disease was 30‒34% for a prevalence of 45%. Diseases of tomato plants in greenhouses in the Kiev region of Ukraine are of bacterial origin, caused by the soft rot pathogen P. carotovorum subsp. carotovorum. Characteristic symptoms of wet tomato rot are discoloration, chlorosis and leaf necrosis, void stems, the appearance of depressed water-saturated areas in the stalk, accompanied by decay of the fetus. Effective control measures can be preventive and agricultural measures

Pseudomonas kitaguniensis sp. nov., a pathogen causing bacterial rot of Welsh onion in Japan

Five Gram-reaction-negative, aerobic, motile with one to three polar flagella, rod-shaped bacterial strains, MAFF 212408T, MAFF 212409, MAFF 212410, MAFF 301498 and MAFF 730085, were isolated from diseased Welsh onion (Allium fistulosum L.) in Japan. Analysis of their 16S rRNA gene sequences showed that they belong to the genus Pseudomonas with the highest similarity to Pseudomonas extremaustralis 14-3T (99.86 %), Pseudomonas antarctica CMS 35T (99.79 %) and Pseudomonas poae DSM 14936T (99.72%). The genomic DNA G+C content was 59.5 mol% and the major fatty acids (>5 %) were summed feature 3, C16 : 0, summed feature 8 and C12 : 0 2-OH. Multilocus sequence analysis using the rpoD, gyrB and rpoB gene sequences and phylogenomic analysis based on the 90 core genes demonstrated that the strains are members of the P. fluorescens subgroup, but are distant from all closely related species. Average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) analysis confirmed low genomic relatedness to their closest relatives [below the recommended thresholds of 95 % (ANI) and 70 % (dDDH) for prokaryotic species delineation]. The strains were characterized by using API 20NE and Biolog GEN III tests, and inoculation tests in Welsh onion, showing that they are phenotypically differentiated from their closest relatives. Based on the genetic and phenotypic evidence, the strains should be classified as representing a novel species, for which the name Pseudomonas kitaguniensis sp. nov. is proposed. The type strain is MAFF 212408T (=ICMP 23530T).

Efficiency of adaptive-integrated potato protection on high inFection background

One of the leading problems in potato growing is the inconsistency of phytosanitary parameters of seed potatoes with the requirements of national standards. This is facilitated by the traditionally used chemical protection of plants, which leads to the selection of resistant strains of pathogens and, as a consequence, a high level of infestation of the planting material. An environmentally oriented approach to potato cultivation technology is adaptive-integrated protection, which implies the creation of integrated plant protection systems against diseases. The aim of the study is to assess the effectiveness of adaptively integrated protection of potatoes against diseases of various etiologies against a high infectious background. The research was carried out in the Laishevsky district of the Tatarstan Republic on the Rodriga variety. According to the results of tuber analysis, it was established that the prevalence rates of diseases exceeded the requirements of GOST 33996-2016. Seed tubers were treated with Revus® fungicide; during the growing season, a double treatment with Famox® and Gymnast® preparations was carried out. In the variant of integrated protection, the treatment was carried out with half the norms of fungicides with the biopreparation Phytosporin®-AS. The use of adaptive-integrated protection of potato during the first growing season led to activation of the destruction of plant residues and an increase in the number of nitrogen-fixing microorganisms, a decrease in the content of phytopathogenic and to increase antagonistic microflora. The biological effectiveness of the integrated protection of Rodriga potatoes on high infectious background against in the first year of vegetation (late blight, vascular wilt of potato, dry rot of potato, black scab, bacterial rot) was 61.5-100%, which led to an increase crop yield.