Page 52 - Book of Abstracts

5 International Scientific Online Conference DOI: https://doi.org/10.15414/2021.9788055224015

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MICROBIOLOGICAL CHARACTERISTICS, PHYSIOLOGICAL AND BIOCHEMICAL
PROPERTIES OF ENDOPHYTIC BACTERIA OF BEAN PLANT NODULES
Svetlana Garipova , Oksana Markova , Natalya Ivanchina , Ramil Khairullin
1
1
1,2
3
1 Bashkir State University, Ufa, Russian Federation; E-mail.: garipovasetlana@gmail.com
2 Bashkir Research Institute of Agriculture, Subdivision of the Ufa Federal Research Centre of the
Russian Academy of Sciences, Ufa, Russian Federation
3 Institute of Biochemistry and Genetics – Subdivision of the Ufa Federal Research Centre of the Russian
Academy of Sciences, Ufa, Russian Federation
Any plant can be considered as a macro-symbiont that organizes mutualistic connections
with beneficial microorganisms, complementing the adaptive potential of a macro-organism
due to its ability to synthesize a variety of physiologically active substances. Root nodules of
legume plants are the nutrient-rich niche that can contain both rhizobia and endophytic
bacteria (EB). Analysis of their metabolic activity indicates that their existence inside a plant
organism can be beneficial to the host. The purpose of this work was a screening of EB from
nodules of Phaseolus vulgaris with plant growth-promoting traits influencing the seed
productivity.
Bacteria were isolated from superficially sterilized nodules on bean-glucose agar, pure
cultures of strains were obtained, their morphological, cultural, tinctorial properties and 16S
rRNA gene sequence were studied. Sterilized plant seeds were inoculated with bacterial
suspension at a density of 10 cells/seed and were germinated on wet filters in the dark at 20-
7
22 °C. Morphometric parameters of sprouts were assessed on 3 and 7 days. The production
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of cytokinins (CK) by EB was determined by the method of biotests for the preservation of
chlorophyll in barley leaves calibrated by 6-benzylaminopurine equivalent. The conditions of
the 3 field experiments in 2010 were extremely drought and in 2015 they were optimal. The
bean plants were sown at a rate of 15 seeds/m with a row spacing of 45 cm. The accounting
plots area for sowing was 3 m . The plots were placed randomly in 4 replicates. Statistical
2
analysis was carried at p < 0.05.
In addition to Rhizobium leguminosarum, the isolated from the nodules of bean plants EB
were spore-forming gram-positive rods. Based on a complex of morphological, cultural, and
biochemical properties, the "satellites" of rhizobia were identified as Bacillus megaterium and
B. subtilis. The taxonomic affiliation of the promising strain 522 (SG12) to the B. subtilis species
was confirmed based on the analysis of the 16S rRNA gene sequence. Depending on strain-
cultivar combination both intensification and inhibition of the growth of the axial organs of the
seedling, shoot/root ratio, and seed germination energy were observed compared to non-
inoculated control. CK production was 600–800 ng/ml. This level was 1.5 times higher than the
production of this hormone by the reference strain R. leguminosarum 1078. As a result of field
trials of EB, a promising strain B. subtilis 522 (collection name of strain SG12) was selected. It
contributed to a twofold increase in comparison with control of the biomass of the shoot and
the number of beans of the Ufimskaya cultivar plants under conditions of an extremely dry
2010 and increased the seed yield of Zolotistaya cultivar plants by 1.5 times compared to non-
inoculated control in relatively in favorable 2015. An increase in the productivity of plants
inoculated with this strain was accompanied by an increase in shoot mass, the setting of a larger
number of beans, and the formation of a larger number of seeds, as well as a greater resistance
of plants to root rot compared to the control. This strain can be further recommended for
production and wider testing.
Keywords: Phaseolus vulgaris, endophytes, PGP-bacteria, Bacillus megaterium, Bacillus subtilis.

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5 International Scientific Conference Agrobiodiversity for Improving the Nutrition, Health, Quality of Life and |51
Spiritual Human Development
November 3 2021
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