Document Type : Original articles
Authors
1
Sugar Crops Research Institute, Agricultural Research Centre, Giza, Egypt
2
Plant Pathology Dept., Fac. of Agric., Ain Shams Univ., P.O. Box 68, Hadyek Shoubra 11241, Cairo, Egypt
Abstract
SYMMARY
In the is study, the endophytic bacteria were isolated from sugarcane stalks and tested for its in vitro antagonistic activity against Sporisorium scitamineum, the causal pathogen of sugarcane smut disease.
Also some physiological characteristics such as its ability to produce some secondary metabolites i.e. PR-proteins and growth-promoters were studied in both in vitro and in vivo. Only, 62 isolates among the total 240 isolates were found to have a bioactivity against the pathogen in vitro. Six isolates from the bioactive isolates were selected for its high antagonistic activity to study its potential to produce the enzymes (chitinase, and β 1,3 glucanase,) and growth-promoters (indole acetic acid (IAA) as well as siderophores and salicylic acid (SA)) in vitro. The selected isolates showed different degrees of antagonistic activity. The selected isolates were identified using the sequencing of the 16S ribosomal RNA (rRna) gene and subjected to mega blast-n in NCBI and proved to be Enterobacter sp.( LUX 27), Kosakonia radicictans (LUX41), Kosakonia radicictans(BAN 33), Klabsiella oxytoca (BAN 39), Bacillus subtilis subsp. Inaquosorum(Q17), Pantoea sp.(SOH 29). In vitro studies proved that, all selected endophytic bacteria produced Nitrogenase and indole acetic acid (IAA) while, Kosakonia radicictans, Klabsiella oxytoca and Bacillus subtilis subsp. Inaquosorum produced salicylic acid. Not one of the selected isolated prove to produce Siderophores. Pantoea sp., Kosakonia radicictans and Klabsiella oxytoca produced chitinase. While, the isolates Kosakonia radicictans and Bacillus subtilis subsp. Inaquosorum were the most effective in producing β 1,3glucanase. The bio-control activity of selected isolates was also studied in vivo under greenhouse conditions on sugarcane infected plants. All the tested isolates were completely reduced the disease compared to the infected control. All the selected endophytic bacteria increased Peroxidase, Chitinase and β-1, 3 glucanaseactivities in the treated plants while the isolates Kosakonia radicictans and Enterobacter sp. didn’t produce Polyphenol-oxidase in treated infected plants. The treated sugarcane plants showed a range of positive increase in Leaf Area, Stalk length, Stalk Diameter, number of tillers and total chlorophyll compared to the untreated healthy and infected control. The present study show the efficiency of using endophytic bacteria as a bio-control system against sugarcane smut.
Keywords
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