Endophytic bacteria in cbold plasma treated sunflower (Helianthus annuus) seeds

Abstract

Endophytic microorganisms are adapted to grow within plant tissues without causing apparent symptoms of plant disease but some of them can promote plant growth by production of plant hormones, modulation of hormone production in plants, increasing nutrient availability or suppressing plant pathogens. Treatment with cold plasma (CP) can inhibit growth of various bacteria, therefore it is applied for food decontamination. Short term seed treatment with CP was reported to improve agronomical crop performance, however the mechanism of such effects is unknown. Possible outcomes of seed CP treatment to some extent may be dependent on changes in composition of endophytic microflora. The aim of our study was to characterize microflora diversity and plant growth promoting properties of endophytic bacteria in control and CP treated sunflower seeds. Seeds of sunflower were treated with CP for 9 and 12 minutes (CP9 and CP12). After treatment the surface of affected and control seeds was sterilized, sunflower kernels were separated from hulls and homogenized. Fresh nutrient medium was added to samples and after vigorous shaking for 30 min samples were inoculated on plates with nutrient medium. Bacterial isolates were characterized by the number of morphological and biochemical properties, including – catalase, oxidase activity, gram staining, secretion of amylolytic and DNA degrading enzymes, ability to reduce nitrate, growth on selective XLD and MSA media. Bacteria isolates were also screened for traits specifically associated with direct and indirect plant growth promotion – auxin production, nitrogen fixation, siderophore production. Gram-positive bacteria dominated in all samples, both cocci and bacilli were present.[...]Biochemijos katedraGamtos mokslų fakultetasVytauto Didžiojo universiteta