Colonization on Cotton Plants with a GFP Labeled Strain of Bacillus axarquiensis
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Colonization on Cotton Plants with a GFP Labeled Strain of Bacillus axarquiensis Bo Wang1 · Chuan‑xing Wan1 · Hong Zeng1 Received: 21 January 2020 / Accepted: 30 May 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Verticillium dahliae was one of the most important diseases caused Verticillium wilt of cotton. In our previous study, Bacillus axarquiensis TUBP1 was screened and found to be an antagonistic strain against V. dahliae with 43% biocontrol effect in the cotton field. In order to uncover the functional mechanism of B. axarquiensis against Verticillium wilt in cotton, the colonization of B. axarquiensis labeled with a green fluorescent protein (GFP) was investigated in cotton plants and the rhizosphere soil. Firstly, a plasmid (pHT-315) containing gfp gene was successfully transformed into wild B. axarquiensis TUBP1 and labeled a green fluorescence by electroporation, which didn’t change the bioactivity in vitro. In gnotobiotic conditions, cotton seeds were then inoculated with the gfp-labeled strain and grown in green house. Observation with a confocal laser scanning microscope and a scanning electron microscope showed that GFP-labeled B. axarquiensis TUBP1 infected cotton roots and widely distributed in epidermis, cortical parenchyma, intercellular spaces, the xylem vessels, and pith cells as well as root hair cells through cracks formed at the lateral root junctions, followed by a slow migration from roots to stems and leaves. Quantitative fluorescence and flow cytometry (FACS) approaches showed a gradual decrease in the number of TUBP1-315gfp with increasing inoculation time. However, TUBP1-315gfp levels were detectable till 45 days after planting. In contrast, no fluorescence signal was detected in the non-inoculated groups. Therefore, GFP-labeled B. axarquiensis TUBP1 exhibited colonization in different parts of cotton plants from the rhizosphere soil.
Introduction Verticillium wilt is one of the disastrous diseases affecting cotton, which seriously damages the yield and crop quality [1]. In recent years, with the rise in green and organic agriculture, the use of biological agents to control Verticillium wilt in cotton has attracted much attention. Many biocontrol products such as GB03, MBI600, Baikang and Mai Fengning have been developed [2, 3]. These products mainly including Bacillus subtilis, which control Verticillum wilt through inhibit plant pathogens directly or can also Hong Zeng and Chuan-xing Wan contributed equally to this work. * Chuan‑xing Wan [email protected] * Hong Zeng [email protected] 1
Xinjiang Production and Construction Corps Key Laboratory of Protection and Utilization of Biological Resources in Tarim Basin/College of Life Science, Tarim University, Alar 843300, Xinjiang, People’s Republic of China
confer induced systemic resistance (ISR) in plants indirectly. Besides, biocontrol products inhibition of pathogen growth by nutrient competition. Bacillus axarquiensis TUBP1 is a Gram-positive biocontrol strain, which was isolated and i
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