Can endophytic Arthrobotrys oligospora modulate accumulation of defence related biomolecules and induced systemic resistance in tomato (Lycopersicon esculentum Mill.) against root knot disease caused by Meloidogyne incognita

The soil community is an often ignored part of research which links plant biodiversity and ecosystem functioning despite their influence on numerous functions such as decomposition and nutrient cycling. Few consistent patterns have been detected that link plant and soil community composition; however, it has not been studied in details. Arthrobotrys oligospora, a model predacious fungus for nematode trapping, beside biocontrol potential may modulate plant health and increase natural antioxidants in tomato fruit directly or indirectly. In the present study we have investigated the effects of nematode trapping fungus A. oligospora on induction and bioaccumulation of natural antioxidant and defence related biomolecules in tomato plants when challenged with Meloidogyne incognita causing root knot. Endophytic and rhizospheric isolates of A. oligospora were isolated from different parts of India and characterized under controlled laboratory conditions. The study describes the multifarious effects of endophytic and rhizospheric isolates of A. oligospora in green house and field conditions in tomato plants when inoculated individually or in combination. It was found that A. oligospora EAO-147 and RST-101 when applied individually or in combination significantly increased various attributes in plants. Among both the isolates, endophytic A. oligospora EAO-147 was found to be more potential in enhancing the defence related biomolecules, enzymes and exhibited biocontrol potentials against M. incognita. With application of A. oligospora, increase in nutritional quality of ripe tomato fruits (mineral nutrients and natural antioxidant properties) was also demonstrated first time. Results suggest that application of A. oligospora, particularly endophytic, not only helps in control of nematodes but also increase plant growth as well as enhances the nutritional value of tomato fruits. Thus, it proves to be an excellent biocontrol as well as plant growth promoting agent.

(A) Tomato root infected by Meloidogyne incognita (arrow showing root gall), (B) Conidia of Arthrobotrys oligospora germinating by forming hyphal loop (750×), and (C) microscopic photographs of hyphal net (600×).Figure optionsDownload as PowerPoint slideHighlights
► Arthrobotrys oligospora modulate physico-chemical and biological properties of soil.
► A. oligospora induce systemic resistance in tomato plants against M. incognita.
► Biocontrol efficacy of endophytic and rhizospheric A. oligospora was tested against M. incognita.
► A. oligospora was found to have potential for improving natural antioxidants and nutritional value of tomato fruits.
► We conclude that both of the biocontrol agents having multifarious characteristics could be a cost effective and eco-friendly.