Defence mechanisms associated with mycorrhiza-induced resistance in wheat against powdery mildew

Abstract

To develop a more sustainable agriculture using alternative control strategies, mechanisms involved in the biocontrol ability of the arbuscular mycorrhizal fungus Funneliformis mosseae to protect wheat against the foliar biotrophic pathogen Blumeria graminis f. sp. tritici were investigated under controlled conditions. B. graminis infection on wheat leaves was reduced by 78% in mycorrhizal plants compared with non-mycorrhizal ones (control). Wheat roots inoculated with F. mosseae revealed a systemic resistance in leaves to B. graminis, after a 6-week co-culture. Accordingly, this resistance was associated with a significant reduction of B. graminis haustorium formation in epidermal leaf cells of mycorrhizal wheat and an accumulation of phenolic compounds and H2O2 at B. graminis penetration sites. Moreover, gene expression analysis demonstrated upregulation of genes encoding for several defence markers, such as peroxidase, phenylalanine ammonia lyase, chitinase 1 and nonexpressor of pathogenesis-related proteins 1 in mycorrhizal wheat only in the absence of the pathogen. This study showed that protection of wheat obtained against B. graminis in response to mycorrhizal inoculation by F. mosseae could be interpreted as a mycorrhiza-induced resistance (MIR). Our findings also suggest that MIR-associated mechanisms impaired the B. graminis development process and corresponded to a systemic elicitation of plant defences rather than a primed state in wheat leaves.

A Review of Studies from the Last Twenty Years on Plant–Arbuscular Mycorrhizal Fungi Associations and Their Uses for Wheat Crops

“…The highest protection level against the pathogen was obtained with F. mosseae (74%), followed by Solrize (58%) and R. irregularis (34%), showing a reduction in the number of conidia with haustorium and an accumulation of polyphenolic compounds at the infection sites. The same positive result was found with the same fungus, F. mosseae, when inoculated on Triticum aestivum L., confirming both the biocontrol ability of the AMF against Blumeria graminis and the mycorrhiza-induced resistance acquired by the plant [108].…”

Identification and Validation of Candidate Genes Conferring Resistance to Downy Mildew in Maize (Zea mays L.)

“…In earlier reports, LOX activity was found to increase in resistant plants and to decrease in susceptible plants. Also, LOX was reported to affect DM and PM resistance of pearl millet and wheat, respectively [84][85][86][87][88]. GRMZM2G028643, GRMZM2G128315, and GRMZM2G330907 (identified as LRR) and GRMZM2G363066 (identified as nonspecific STK) were associated with defense reactions against pathogens.…”

Omics approaches revealed how arbuscular mycorrhizal symbiosis enhances yield and resistance to leaf pathogen in wheat

“…The contrasting results obtained in such studies suggest that induction of resistance against pathogens depends on multiple mechanisms that may operate simultaneously 4 , 31 , 33 , 34 . The potential protective effect of mycorrhizal symbiosis in wheat has been poorly investigated 35 , 36 . The main goals of this work were, first, to define the responsiveness of T .…”