Aspergillus alliaceus infection fatally shifts Orobanche hormones and phenolic metabolism

Abstract

In this study, the physio pathological effects of Aspergillus alliaceus (Aa, fungi, biocontrol agent) on Orobanche (parasitic plant) were investigated by hormone and phenolic substance tests. In experimental group, Orobanches were treated with the fungi, considering control group was fungus-free. Based on the hormonal tests, in the experimental group, salicylic acid (SA), jasmonic acid (JA), abscisic acid (ABA) and gibberellic acid (GA) levels significantly decreased, and only indole acetic acid (IAA) hormone levels were fairly higher than the control group. According to phenolic substance tests, it was found that only gallic acid, syringic acid and caffeic acid values significantly increased compared with control, and catechin and p-coumaric acid values were significantly lower. Consequently, it was determined that Aa pathogenesis (1) considerably reduces the effects of all defence hormones (JA, ABA, SA), (2) operates an inadequate defence based solely on the IAA hormone and several phenolic substances (gallic acid, syringic acid and caffeic acid), (3) and inevitably the fungi lead the Orobanche to a slow and continuous death. The results were evaluated in detail in the light of similar recent article and current literature in terms of biocontrol and pathology.

Keywords: Asteraceae; Bioherbicide; Herbicide; Mycoherbicide; Phelipanche; Phytoparasite.

Fig. 1

a One healthy Orobanche belonging to the control group (fungus-free) in pots (arrows). b Control group Orobanches on the host (sunflower), removed from the soil (arrows). c The fungus used, A. alliaceus, its view on 20% Czapek yeast–sucrose–agar media (CYA20S). d Due to fungal infection, an Orobanche stem with darkened bottom (arrows) (the upper sides are still healthy). e Orobanche stems (white arrows) completely dead by fungal infection, and fungal mycelium residues (yellow arrowheads) on it. f Small Orobanches, healthy (on the left), completely dark and dead (in the middle and right ones) with the accumulation of phenols after the fungal infection

Fig. 2

Hormone levels in control and experimental groups. IAA, indoleacetic acid, F = 5819,094, df = 3, P = 0.0000*; GA, gibberellic acid, F = 1710,269, df = 3, P = 0.0000*; ABA, abscisic acid, F = 993,159, df = 3, P = 0.0000*; SA, salicylic acid, F = 55,878, df = 3, P = 0.0000*, JA, jasmonic acid, F = 72,827, df = 3, P = 0.0000*. The numbers in the columns define standard error data. * indicates significant differences between control and Aspergillus infected experimental groups according to one-way ANOVA, Duncan test (p ≤ 0.05)

Fig. 3

Phenol levels in control and experimental groups. Catechine, F = 292,923, df = 3, P = 0.0000*; Gallic acid, F = 70,490, df = 3, P = 0.0000*; Syringic acid, F = 503,436, df = 3, P = 0.0000*; Caffeic acid, F = 403,271, df = 3, P = 0.0000*; P-coumaric acid, F = 154,457,138, df = 3, P = 0.0000*. The numbers in the columns define standard error data. * indicates significant differences between control and Aspergillus infected experimental groups according to one-way ANOVA, Duncan test (p ≤ 0.05)