Exogenous Trehalose Induces Defenses in Wheat Before and During a Biotic Stress Caused by Powdery Mildew

Abstract

Powdery mildew would be one of the most damaging wheat diseases without the extensive use of conventional fungicides. Some of the alternative control strategies currently emerging are based on the use of resistance inducers. The disacharride trehalose (TR) is classically described as an inducer of defenses in plants to abiotic stress. In this work, the elicitor or priming effect of TR was investigated in wheat both before and during a compatible wheat-powdery mildew interaction through molecular, biochemical, and cytological approaches. In noninoculated conditions, TR elicited the expression of genes encoding chitinase (chi, chi1, and chi4 precursor), pathogenesis-related protein 1, as well as oxalate oxidase (oxo). Moreover, lipid metabolism was shown to be altered by TR spraying via the upregulation of lipoxygenase (lox) and lipid-transfer protein (ltp)-encoding gene expression. On the other hand, the protection conferred by TR to wheat against powdery mildew is associated with the induction of two specific defense markers. Indeed, in infectious conditions following TR spraying, upregulations of chi4 precursor and lox gene expression as well as an induction of the LOX activity were observed. These results are also discussed with regard to the impact of TR on the fungal infectious process, which was shown to be stopped at the appressorial germ tube stage. Our findings strongly suggest that TR is a true inducer of wheat defense and resistance, at least toward powdery mildew.

Triticum monococcumlines with distinct metabolic phenotypes and phloem-based partial resistance to the bird cherry-oat aphidRhopalosiphum padi

“…Trehalose is a disaccharide, which is found in the majority of plants in only trace amounts and has been thought to control basic plant processes as well as being involved in resistance to abiotic stress factors and signalling. More recent work is now showing that it is trehalose‐6‐phosphate, a precursor of trehalose, which is the signalling molecule (Paul et al , 2008; O'Hara et al , 2013) and interestingly it has been shown that treating wheat with trehalose can induce partial protection against the powdery mildew pathogen ( Blumeria graminis ), which could be because of the activation of defence responses (Reignault et al , 2001; Tayeh et al , 2014). Trehalose is important to insects, as the starting point in chitin synthesis (Paul et al , 2008) and is known to occur in the haemolymph of the aphids Megoura viciae and Acyrthosiphon pisum (Rhodes et al , 1997).…”

Exogenous application of trehalose alters growth, physiology and nutrient composition in radish (Raphanus sativus L.) plants under water-deficit conditions

“…Although a number of studies reports are available in the literature which show a significant effect of trehalose on abiotic stress tolerance in different crops (Iordachescu and Imai 2008;Ali and Ashraf 2011;Li et al 2011;Ali et al 2012), a little information is found regarding the effect of trehalose on membrane permeability/leakage except that of Tayeh et al (2014) on wheat plants in which they observed that exogenously applied trehalose improved lipid metabolism due to upregulation of lipoxygenase and lipid-transfer protein under stress conditions. In radish plants, reduced accumulation of essentially required mineral nutrients for optimum growth such as K ?…”

A Tale of Two Sugars: Trehalose 6-Phosphate and Sucrose

“…and Xanthomonas citri subsp. citri (Freeman et al, 2010;Djonovi c et al, 2013;Piazza et al, 2015), but is a double-edged sword for the pathogens as it is also a trigger for defense responses by the host plant (Reignault et al, 2001;Renard-Merlier et al, 2007;Tayeh et al, 2014;Piazza et al, 2015). Trehalose is also implicated as a signal molecule during formation of rhizobial and mycorrhizal symbioses (Fig.…”