Mechanism of seedling protection induced by a hypovirulent isolate of Rhizoctonia solani

1989 ◽  
Vol 67 (7) ◽  
pp. 2135-2141 ◽  
Author(s):  
B. Sneh ◽  
M. Ichielevich-Auster ◽  
Z. Plaut
Keyword(s):  
Biological Control ◽  
Cell Wall ◽  
Plant Growth ◽  
Rhizoctonia Solani ◽  
Growth Response ◽  
Damping Off ◽  
Produce Cell ◽  
Protected Plants ◽  
Hypovirulent Strain ◽  
Seedling Protection

Among several hypovirulent isolates of Rhizoctonia spp. tested, one isolate (No. 521) provided significantly higher protection (76–94%) to radish and cotton seedlings against infection by virulent isoltes of Rhizoctonia spp. and also induced a higher increased plant growth response than the others. The hypovirulent strain did not compete for root exudates. The protected plants were not induced to produce new polyphenols, melanins, more lignins, or phytoalexins. Also they did not produce inhibitors of pectinases or cellulases released by the pathogen, nor did they produce cell wall lytic-type enzymes, such as chitinase and β-(1,3) glucanase. Ca2+ content was significantly higher in seedlings colonized by the hypovirulent isolate. The hypovirulent isolate densely colonized the surface of roots and hypocotyls, and removal of its hyphae nullified the protection provided by this isolate. Key words: Rhizoctonia solani, damping-off, hypovirulent isolate, biological control.

scholarly journals Application of plant extracts and Trichoderma harzianum for the management of tomato seedling damping-off caused by Rhizoctonia solani

2020 ◽  
Vol 116 (11/12) ◽  
Author(s):  
Mapula T.P. Hlokwe ◽  
Mapotso Kena ◽  
David N. Mamphiswana
Keyword(s):  
Biological Control ◽  
Rhizoctonia Solani ◽  
Plant Extracts ◽  
Trichoderma Harzianum ◽  
Moringa Oleifera ◽  
Plant Diseases ◽  
Yield Reduction ◽  
Biotic Factors ◽  
Damping Off ◽  
Tomato Seedling

Seedling production under smallholder farming systems can be negatively affected by both abiotic and biotic factors. Seedling damping-off caused by Rhizoctonia solani is one of the major biotic factors which causes significant yield reduction. Management is mainly based on the application of synthetic fungicides and cultural practices. However, both methods have limitations which result in their inefficiency. Several studies have reported on the use of plant extracts and biological control to manage plant diseases. The aim of this study was to formulate an effective and practical approach to manage tomato seedling dampingoff using extracts of Monsonia burkeana and Moringa oleifera and a biological control agent Trichoderma harzianum. The efficacy of both extracts was investigated under laboratory conditions to determine the most suppressive concentration to R. solani growth. Methanolic extracts from both plants significantly suppressed pathogen growth at different concentrations. M. burkeana significantly reduced R. solani growth at 8 g/mL (71%) relative to control whilst Moringa oleifera extract reduced pathogen growth by 60% at a concentration of 6 g/mL. The highest suppressive concentrations were further evaluated under greenhouse conditions to test their efficacy on seedling damping-off. In damping-off treatments, both plant extracts and T. harzianum also significantly reduced (p=0.5) pre- and post-emergence dampingoff incidence. M. burkeana recorded the highest suppression at 78%, followed by M. oleifera at 64%. Trichoderma harzianum reduced incidence of damping-off by 60% and this was higher than both plant extract treatments.

scholarly journals Selection and Assessment of Plant Growth-Promoting Rhizobacteria for Biological Control of Multiple Plant Diseases

2017 ◽  
Vol 107 (8) ◽  
pp. 928-936 ◽  
Author(s):  
Ke Liu ◽  
Molli Newman ◽  
John A. McInroy ◽  
Chia-Hui Hu ◽  
Joseph W. Kloepper
Keyword(s):  
Biological Control ◽  
Plant Growth ◽  
Broad Spectrum ◽  
Plant Growth Promoting Rhizobacteria ◽  
Plant Diseases ◽  
Damping Off ◽  
In Planta ◽  
Plant Growth Promoting ◽  
Growth Promoting

A study was designed to screen individual strains of plant growth-promoting rhizobacteria (PGPR) for broad-spectrum disease suppression in vitro and in planta. In a preliminary screen, 28 of 196 strains inhibited eight different tested pathogens in vitro. In a secondary screen, these 28 strains showed broad spectrum antagonistic activity to six different genera of pathogens, and 24 of the 28 strains produced five traits reported to be related to plant growth promotion, including nitrogen fixation, phosphate solubilization, indole-3-acetic acid production, siderophore production, and biofilm formation. In advanced screens, the 28 PGPR strains selected in vitro were tested in planta for biological control of multiple plant diseases including bacterial spot of tomato caused by Xanthomonas axonopodis pv. vesicatoria, bacterial speck of tomato caused by Pseudomonas syringae pv. tomato, damping-off of pepper caused by Rhizoctonia solani, and damping-off of cucumber caused by Pythium ultimum. In all, 5 of the 28 tested strains significantly reduced three of the four tested diseases, and another 19 strains showed biological control to two tested diseases. To understand the observed broad-spectrum biocontrol capacity, antiSMASH was used to predict secondary metabolite clusters of selected strains. Multiple gene clusters encoding for secondary metabolites, e.g., bacillibactin, bacilysin, and microcin, were detected in each strain. In conclusion, selected individual PGPR strains showed broad-spectrum biocontrol activity to multiple plant diseases.

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