Identification and application of biocontrol agents against Cotton leaf curl virus disease in Gossypium hirsutum under greenhouse conditions

Abstract

Biological control is a novel approach in crop protection. Bacteria, such as Bacillus spp. and Pseudomonas spp., are reported for this purpose and some of their products are already commercially available. In this study, the rhizosphere and phyllosphere of healthy cotton plants were used as a source of bacterial isolates with properties of potential biocontrol agents. The isolates were screened for phosphate solubilization activity, indole acetic acid (IAA) production and antifungal activity. Two isolates, S 1 HL 3 and S 1 HL 4 , showed phosphate solubilization and IAA production simultaneously, while another two, JS 2 HR 4 and JS 3 HR 2 , demonstrated potential to inhibit fungal pathogens. These bacteria were identified as Pseudomonas aeruginosa (S 1 HL 3), Burkholderia sp. (S 1 HL 4) and Bacillus sp. (JS 2 HR 4 and JS 3 HR 2) based on biochemical and molecular characteristics. The isolates were tested against Cotton leaf curl virus (CLCuV) in greenhouse conditions, both as individual bacterial isolates and consortia. Treated plants were healthy as compared to control plants, where up to 74% of the plants were symptomatic for CLCuV infection. Maximum inhibition of CLCuV was observed in the plants treated with a mixture of bacterial isolates: the viral load in the treated plants was only 0.4% vs. up to 74% in controls. This treatment consortium included P. aeruginosa S 1 HL 3 , Burkholderia sp. S 1 HL 4 and Bacillus spp. isolates, JS 2 HR 4 and JS 3 HR 2. The principal-component biplot showed a highly significant correlation between the viral load percentage and the disease incidence.

Characterization of broad-spectrum biocontrol efficacy of Bacillus velezensis against Fusarium oxysporum in Triticum aestivum L.

“…Isolation of bacteria with antagonistic activity against phytopathogenic fungi A total of 360 samples from the phyllosphere and rhizosphere of different crops, including maize, potato, apple, pomegranate, barley, cotton, grapes, and wheat, were collected from different fields of Quetta, Baluchistan, Pakistan and processed at Applied Biotechnology Laboratory, Balochistan University of Information Technology, Engineering and Management Sciences (BUITEMS). The phyllosphere samples were processed as described by Ramzan et al (2016), and rhizosphere samples were processed as described by Tsegaye et al (2019). By using the spread plate method, 1 ml of each 10 -6 CFU/ml diluted sample was spread on Luria Bertani agar (LBA) media, and plates were incubated at 28±2 °C for 72 hours.…”

“…The inferred sequences were deposited in the GenBank database, and accession numbers were obtained. The identification of phylogenetic neighbours and calculation of highly analogous sequences were carried out by using the National Center for Biotechnology Information (NCBI); similarly, the phylogenetic tree was created in MEGA-X by using the first 50 BLAST hits (Ramzan et al, 2016).…”

Present status of cotton leaf curl virus disease (CLCUVD): a major threat to cotton production

“…isolates, JS3HR2 and JS2HR4, Burkholderia sp. S1HL4 and P. aeruginosa S1HL3 was used under greenhouse conditions (Ramzan et al, 2016). Management of CLCuVD: Various factors affect the occurrence, incidence, severity and economic losses caused by cotton leaf curl disease.…”

Harnessing Nanoencapsulated Bacillus spp. Consortia To Combat Groundnut Bud Necrosis Orthotospovirus in Tomato

“…Bacillus amyloliquefaciens strain MBI600 also reduced TSWV incidence in both plant growth chamber and greenhouse conditions . The role of PGPR against virus diseases in different crops has been explored by various research groups. − Bacillus spp. colonizes plant roots and enhances growth by nutrient absorption, growth factors, and vitamins.…”