Plant‐Bacteria Interactions

Abstract

SummaryBacillus amyloliqufaciens FZB42 has been known as PGPR which has an impressive effect to improve plant growth. It produces not only vast array of secondary metabolites with antibacterial and antifungal activities, but also produces the plant hormone IAA. Although many mechanisms have been elucidated, our knowledge about basic molecular mechanisms responsible for its beneficial action is far from complete. In this study, transposon mutagenesis based on mariner tranposon was applied to generate tranposon library which then was screened to identify the genes involved in plant growth-promoting activity. Three mutants that were impaired in their ability to colonize plant surface due to defects in biofilm formation and swarming motility were found. One mutant (degU mutant) showed defect in biofilm formation and swarming motility, as well, two mutants (yusV mutant and pabB mutant) impaired in biofilm formation were confirmed by complementation and retransformation. Screening by the Lemna biosystem and further assays with A. thaliana revealed three genes responsible for reduction in plant growth promoting activity of B. amyloliqufaciens FZB42. Colonization studies of these mutants in A. thaliana roots revealed patterns different to the wild type. A further issue pursued in this study was to discover new antibiotics using a mutant which has been blocked in its nonribosomally pathway. Screening of tranposon librabries from this mutant led to the finding of two novel ribosomally synthesized antibiotics. Further characterization revealed that these new antibiotics belonged to a novel bacteriocin (Amylocyclicin A) and a novel thiazole/oxazole-modified microcin (Plantazolicin). Last work in this study was looking for genes responsible for nematocidal production. Four mutants which showed reduction in nematocidal activity due to transposon insertion were found.

Efficacy of Application of Biostimulants Based on Non-pathogenic Microorganisms when Growing Okra in Arkansas

“…Biostimulants di h f b [ ] Bi i l available in the marketplace include bacteria, fungi, seaweed, higher plants, animals and humate-containing raw materials. Bacteria interact with plants in all possible ways [5]. Plant growth-promoting rhizobacteria are ways [5].…”

“…Bacteria interact with plants in all possible ways [5]. Plant growth-promoting rhizobacteria are ways [5]. Plant growth-promoting rhizobacteria are multifunctional and infl uence all aspects of plant life: nutrition and growth, morphogenesis and development, response to biotic and abiotic stress, interactions with other organisms in the agroecosystems [6][7][8][9][10][11][12].…”