Biological Control of a Severe Viral Strain of Cucumber Mosaic Virus(CMV) Using a Mild Strain of CMV Associated with Viral Satrna Combined with a Mixture of Plant Growth Promoting Rhizobacteria (PGPRs)
Magdy S. Montasser*, Narjes H. Dashti, Nedaa Y. Ali, Vineetha M. Cherian
The effect of using plant growth promoting rhizobacteria (PGPR) as compensatory agents to nullify the detrimental growth effects that occur when using satRNA mediated protective technology were studied in greenhouse grown chilli pepper. A benign cucumber mosaic virus strain (CMV) associated with satRNA, CMV-KU1, was successfully used as a biological control agent to combat infections caused by another severe strain of CMV , CMV-16. However, despite its protective capability, CMV-KU1 caused certain vegetative and yield loss to the plants to which it was applied. A mixture of two known PGPR strains, Pseudomonas aeruginosa and Stenotrophomonas rhizophilia were used in this investigative study to see if this loss can be reversed or compansated. Additionally, three different routes of PGPR application to the plants were also tested to determine which would provide the best result in promoting plant growth and reducing infections. The three PGPR application pathways tested were i) application directly to the rhizosphere of the plants by injection to the roots, ii) coating of the seeds with PGPRs before sowing, and iii) mixing of the PGPRs with the soil before sowing. Observations were made based on the manifested symptoms of the infected plants, fruit yield and ELISA readings. The resulting data were statistically analysed. The results indicated that the presence of PGPRs significantly improved the plant growth, yield, fruit number and fruit set rate in chilli pepper compared to using satRNA alone. Moreover, the best results were obtained when PGPRs were directly inoculated into the rhizosphere compared to the two other alternative application methods tested.
