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

Abstract

BackgroundMechanisms involved in the biological control of plant diseases are varied and complex. Hormones, including the auxin indole acetic acid (IAA) and abscisic acid (ABA), are essential regulators of a multitude of biological functions, including plant responses to biotic and abiotic stressors. This study set out to determine what hormones might play a role in Pseudomonas fluorescens –mediated control of Fusarium head blight (FHB) disease of barley and to determine if biocontrol-associated hormones directly affect disease development.ResultsA previous study distinguished bacterium-responsive genes from bacterium-primed genes, distinguished by the fact that the latter are only up-regulated when both P. fluorescens and the pathogen Fusarium culmorum are present. In silico analysis of the promoter sequences available for a subset of the bacterium-primed genes identified several hormones, including IAA and ABA as potential regulators of transcription. Treatment with the bacterium or pathogen resulted in increased IAA and ABA levels in head tissue; both microbes had additive effects on the accumulation of IAA but not of ABA. The microbe-induced accumulation of ABA preceded that of IAA. Gene expression analysis showed that both hormones up-regulated the accumulation of bacterium-primed genes. But IAA, more than ABA up-regulated the transcription of the ABA biosynthesis gene NCED or the signalling gene Pi2, both of which were previously shown to be bacterium-responsive rather than primed. Application of IAA, but not of ABA reduced both disease severity and yield loss caused by F. culmorum, but neither hormone affect in vitro fungal growth.ConclusionsBoth IAA and ABA are involved in the P. fluorescens-mediated control of FHB disease of barley. Gene expression studies also support the hypothesis that IAA plays a role in the primed response to F. culmorum. This hypothesis was validated by the fact that pre-application of IAA reduced both symptoms and yield loss asssociated with the disease. This is the first evidence that IAA plays a role in the control of FHB disease and in the bacterial priming of host defences.

Physcomitrella patens auxin conjugate synthetase (GH3) double knockout mutants are more resistant to Pythium infection than wild type

“…Similarly, infection with e.g. Fusarium species (Fernández-Falcón et al, 2003;Petti et al, 2012), Magnaporthe grisea (Ueno et al, 2004) and Botrytis sp. (Yu et al, 2008) could also be controlled by application of IAA.…”

Cendawan Endofit Akar Lada Untuk Meningkatkan Pertumbuhan Dan Menekan Busuk Pangkal Batang Benih Lada

“…Pseudomonas fluoresecens yang diinokulasikan pada gandum memacu terbentuknya IAA pada pucuk tanaman sehingga menekan gejala dan kehilangan hasil akibat penyakit hawar pucuk Fusarium (Petti et al 2012); tetapi hal tersebut tidak berlaku untuk hormon ABA (Mejia et al 2008). Mekanisme penekanan patogen yang ditemukan pada tanaman kakao oleh endofit Trichoderma umumnya kompetisi untuk substrat atau ruang (Hakkar et al 2014).…”

In Vitro Antifungal Activity of Different Plant Hormones on the Growth and Toxicity of Nigrospora Spp. on Date Palm (Phoenix dactylifera L.)

“…This weak inhibition response is in agreement with the results of Alam et al [19] who reported that both IAA and BAP led to a weak inhibition (4 and 11%; respectively) to the mycelium growth of anthracnose fungal pathogen (Colletotrichum spp.). Petti et al [49] reported that IAA has no effect on F. culmorum growth when using a nutrient-rich medium.…”