Systemic protection against pearl millet downy mildew disease induced by cell wall glucan elicitors from Trichoderma hamatum UOM 13

Abstract

The obligate oomycete Sclerospora graminicola (Sacc.) Schroet, is the incitant of downy mildew disease, which is the main constraint in pearl millet production worldwide. Different elicitors from Trichoderma hamatum UOM 13, e.g. mycelial extract and cell wall glucans, were assessed for their resistance elicitation efficiency and the possible underlying mechanisms. Both mycelial extract and cell wall glucans of T. hamatum UOM 13 positively influenced seed quality parameters of pearl millet, significantly enhanced seed germination and seedling vigor in comparison to the untreated control. Seed priming with cell wall glucan elicitors of T. hamatum UOM 13 suppressed downy mildew on susceptible pearl millet seedlings under greenhouse conditions by induction of systemic host resistance. Of the different elicitor delivery methods tested, transplant root dip was more effective than seed treatment and foliar spray. A combination of transplant root dip + seed treatment + foliar spray was significantly more effective than the single delivery methods. The induced resistance corresponded to up regulation of genes of important defense proteins upon pathogen inoculation. Transcripts of genes of defense enzymes glucanase, phenylalanine ammonia lyase, peroxidase and polyphenoloxidase were significantly increased due to the T. hamatum UOM elicitor effect. Expression of hydroxyproline-rich glycoprotein genes, known to play an important role in cell wall cross-linking, were also up regulated in response to T. hamatum UOM cell wall glucan treatment. This study emphasizes the role of T. hamatum UOM as a potential elicitor of downy mildew resistance in pearl millet and presents novel insights into the involvement of important defense proteins mediating such as resistance trigger.

Trichovariability in rhizosphere soil samples and their biocontrol potential against downy mildew pathogen in pearl millet

“…Cell wall glucan of T. hamatum UOM 13 was found to suppress the DM diseases in PM by inducing systemic resistance 74 . Further Siddaiah et al .…”

Lipopolysaccharide-induced priming enhances NO-mediated activation of defense responses in pearl millet challenged with Sclerospora graminicola

“…Elicitor signaling primes the host defense responses in plants and effectively offers resistance against pathogens by mechanisms such as cell-wall reinforcement, production of antimicrobial metabolites, expression of defense enzymes and proteins, and hypersensitive responses (Lorrain et al 2003;Lavanya et al 2017). LPS is an elicitor of systemic resistance in many crops.…”

Induction of systemic resistance to Orobanche crenata in lentil by exogenous application of salicylic acid and indole acetic acid

“…Plant growth regulators, elicitors and other environmentally friendly compounds, have been used to enhance plant health, plant defense mechanisms and improve the resistance against various pathogens including fungi, bacteria, viruses and parasitic weeds (Šindelářová et al 2002;Achuo et al 2004;Sillero et al 2012;Abbes et al 2014;Lavanya et al 2017;Triki et al 2018;Almas et al 2019;Briache et al 2020). Exogenous application of these compounds can put the plant in an activated state and cause a defensive response similar to that against invasion by pathogens (Qamar et al 2015).…”