Journal of Pure and Applied MicrobiologyVol. 8 No. May 2014 Special Edition

Bean (Phaseolus vulgaris, L.) Damping-off Caused by Pythium ultimum var. ultimum and its Possible Control by Pythium oligandrum

M.A. Elnaghy2, H.M.A. Abdelzaher1,2, M.A. Shoulkamy2,3 and S.R. Mohamed2,4

1Department of Biology, College of Science, Aljouf University, Sakaka, 42421, Saudi Arabia. 2Department Botany and microbiology, College of Science, Minia University, El-Minia, 61511, Egypt. 3Department of Biology, College of Science, Jazan University, Jazan, 45142, Saudi Arabia. 4Department of Zoology (EM unit), College of Science, King Saud University, Riyadh 11451, Saudi Arabia.

Received on 23 February 2014 and accepted on 30 April 2014

 

ABSTRACT

The effectiveness of Pythium oligandrum as a bio-control agent against P. ultimum var. ultimum was investigated to avoid harmful fungicides effects. Three isolates of P. oligandrum (MS15, MS19 and MS31) were evaluated against the plant pathogenic P. ultimum Trow var. ultimum the causative agent of Phaseolus vulgaris damping-off. Pythium species were identified according to their respective morphologically and sequencing of rDNA-ITS fragments including the 5.8 S rDNA to confirm the species identification. The three isolates of P. oligandrum reduced the mycelial growth of P. ultimum var. ultimum with 64.44, 65.56 and 66.76% during mycoparasitism on PDA plates while the millipored sterilized filtrates of P. oligandrum isolates reduce the pathogenic mycelial growth by 16.67, 17.78 and 18.89% respectively. Scanning electron microscope (SEM) of the strongest antagonistic isolate (MS31) interaction revealed coiling, haustorial branches, infection pegs and penetration of P. oligandrum to P. ultimum var. ultimum hyphae. On the other hand, P. oligandrum isolates improved emergence of Phaseolus vulgaris seedling from 0-100% in damping-off disease using agar bottles and from 13.33 - 86.66% during pot experiments compared with the control.

Keywords : Biological control, Damping-off, Phaseolus vulgaris, P. oligandrum, P. ultimum var. ultimum.