Pathogenicity of indole-3-acetic acid producing fungus Fusarium delphinoides strain GPK towards chickpea and pigeon pea

Abstract

An indole-3-acetic acid (IAA) producing fungal strain was isolated from chickpea grown rhizospheric soil samples. Based on morphological and Internal Transcribed Spacer (ITS) region sequence analysis the new isolate was identified as Fusarium delphinoides. The Fusarium delphinoides strain produces and secretes IAA in-vitro as identified by HPLC and Mass spectrometry. The IAA production is dependent on tryptophan (Trp) as a nitrogen source in the medium. The IAA production is influenced by growth conditions such as pH of the medium, concentration of Trp and the nature of the carbon source. Additional nitrogen sources repress Trp dependent IAA production. Glucose and Trp served as the best carbon and nitrogen sources respectively. Pathogenicity of Fusarium delphinoides towards the plants was tested by electrolyte, nutrient leakage analysis and also by scoring the disease symptoms. Two cultivars of chickpea (ICCV-10 and L-550) and two cultivars of pigeon pea (Maruti and PT-221) were assessed for the pathogenicity by inoculating with spores of Fusarium delphinoides. The inoculation induced symptoms of Fusarium wilt as in the case of Fusarium oxysporum f. sp. ciceris (FOC), a known pathogen causing Fusarium wilt in chickpea. Electrolyte and nutrient leakage from the infected plants were used to assess the resistance, tolerance (moderately resistance) and susceptibility of the plants to the infection. Based on the results, both the pigeon pea cultivars (Maruti and PT-221) were rated as resistant, and ICCV-10 was rated as a tolerant cultivar of chickpea. However, chickpea cultivar L −550 was found to be a susceptible host for infection by Fusarium delphinoides. These results suggest that Fusarium delphinoides, which belongs to the Fusarium dimerum species group, is an IAA producing plant pathogen and causes wilt in chickpea. Further, along with pathogenicity tests, electrolyte and nutrient leakage analysis can be used to assess the pathogenicity of pathogenic fungi.

Production of Indole Acetic Acid by a Wood Degrading Fungus Phanerochaete chrysosporium

“…However, an adjacent peak was also observed, which might belong to some related indole compound (indole-3-carboxylic acid) or amino acid conjugate (IAA-Ala) as described earlier during the HPLC determination of IAA [22,23]. Similarly, HPLC analysis of IAA produced by fungus Fusarium delphinoides showed the comparable peaks to present study [24].…”

Auxin as a player in the biocontrol of Fusarium head blight disease of barley and its potential as a disease control agent

“…P. fluorescens strain MKB158 has the capacity to produce auxin [34], as do Fusarium fungi [35]. Based on the literature [36-38], it is very possible that the IAA is derived from the bacterium and/or pathogen rather than the plant; the application of IAA might trick the plant into thinking it is being attacked by the pathogen, thus priming the defences responses such that they are activated to respond rapidly to the pathogen and thus increase plant FHB resistance. Fusarium culmorum displays a hemibiotrophic lifestyle [39] and there is evidence that auxin signalling enhances resistance to necrotrophs but susceptibility to biotrophs [40-42].…”

Fusarium: more than a node or a foot-shaped basal cell

“…The fusarioid genus Bisifusarium is known to produce the PKS/NRPS hybrid siderophore, dimerumic acid (= dimerum acid) ( Diekmann 1970 ), and indole acetic acid ( Reddy & Reddy 1992 , Kulkarni et al. 2011 , 2013 ).…”