In Vitro Approbation of Microbial Preparations to Shield Fruit Crops from Fire Blight: Physio-Biochemical Parameters.

The need for the increasing geographical spread of fire blight (FB) affecting fruit crops to be addressed led to large-scale chemicalization of the environmental matrices and reduction of plant productivity. The current study aimed to assess the effects of novel biopreparations at different exposure durations on photosynthetic pigment content and antioxidant enzyme activity in leaves of apple and pear varieties with varying levels of resistance to FB. Biopreparations were formulated from a cultural broth containing Lacticaseibacillus paracasei M12 or Bacillus amyloliquefaciens MB40 isolated from apple trees' phyllosphere. Aseptic leaves from blight-resistant (endemic Malus sieversii cv. KG10), moderately resistant (Pyrus pyraster cv. Wild), and susceptible (endangered Malus domestica cv. Aport and Pyrus communis cv. Shygys) varieties were employed. The impact of biopreparations on fruit crop antioxidant systems and photosynthetic apparatuses was investigated in vitro. Study results indicated that FB-resistant varieties exhibit enhanced adaptability and oxidative stress resistance compared to susceptible ones. Plant response to biopreparations varied based on the plant's initial FB sensitivity and exposure duration. Indeed, biopreparations improved the adaptive response of the assimilation apparatus, protein synthesis, and catalase and superoxide dismutase activity in susceptible varieties, suggesting that biopreparations have the potential for future commercialization to manage FB in fruit crops.

Antagonistic and protective activity of Lactobacillus plantarum strain 17 M against E. amylovora.

The subject of the study was to identify the antagonism of the Lactobacillus plantarum strain 17 M against the causative agent of fire blight, the bacterium Erwinia amylovora, and to evaluate its protective capabilities on apple blossoms against this disease. For comparison 9 strains of lactic acid bacteria from the LLP "SPC of Microbiology and Virology" collection were included in the study. Strain 17 M appeared to be superior in limiting the growth of the pathogen on all 3 liquid media tested. Its maximum inhibitory activity was proved on MRS Broth medium. The analysis of the secondary metabolites produced by strain 17 M in liquid medium revealed that it consisted mainly of acetic acid (53.2 ± 4.3%), lactic acid (16.3 ± 2.3%) and 2,3-butanedione (14.84 ± 4.1%). The presence of other organic compounds was also detected but in a smaller amount. Study on influence of those compounds on growth of E. amylovora showed that lactic acid at concentration of 5% showed inhibitory activity but it was not toxic to apple flowers. The effectiveness of strain 17 M culture liquid diluted with sterile water and added to E. amylovora inoculum at 10% or 20% was 76.7 ± 5.8% and 88.3 ± 12.6%, respectively. This study confirms the potential use of strain 17 M as an active microbial agent to combat fire blight of fruit crops in Kazakhstan.

Occurrence of Spot Blotch in Spring Barley Caused by Bipolaris sorokiniana Shoem. in South-Eastern Kazakhstan.

In Kazakhstan, barley (Hordeum vulgare L.) is the second most important cereal crop after wheat, with an annual production of approximately 1.9 million tons. The study aimed to characterize Bipolaris sorokiniana isolates obtained from barley fields surveyed. A total of 21 diseased leaves showing spot blotch symptoms were collected from experimental plots located close to the Kazakh Research Institute of Agriculture and Crop Production, where the spring barley Arna cultivar was planted in June 2020. The overall strategy for control of spring barley blotch in the Almaty region of Kazakhstan should include the determination of the aggressiveness of the pathogen isolates to better understand the biology of the diseases and ultimately proper control strategy. Pathogenicity of B. sorokiniana isolates was made on barley seedlings in vitro. Inoculated seedlings showed clear symptoms of B. sorokiniana, and therefore, Koch's postulates were fulfilled by reisolating the pathogen from artificially inoculated seedlings and identifying it based on standard morphology criteria. Further investigation is needed to understand the impact of B. sorokiniana on barley production in Kazakhstan.