LPMO-oxidized cellulose oligosaccharides evoke immunity in Arabidopsis conferring resistance towards necrotrophic fungus B. cinerea

Marco Zarattini,Irma Milanese,Mariana Ortiz De Godoy,Sylvie Jolivet,Massimiliano Corso,Marco Antonio Kadowaki,Christian Hermans,Antonielle Monclaro,David Cannella,Silvia Magri,Mathilde Fagard

doi:10.1038/s42003-021-02226-7

Abstract

Lytic Polysaccharide Monooxygenases (LPMOs) are powerful redox enzymes able to oxidatively cleave recalcitrant polysaccharides. Widely conserved across biological kingdoms, LPMOs of the AA9 family are deployed by phytopathogens to deconstruct cellulose polymers. In response, plants have evolved sophisticated mechanisms to sense cell wall damage and thus self-triggering Damage Triggered Immunity responses. Here, we show that Arabidopsis plants exposed to LPMO products triggered the innate immunity ultimately leading to increased resistance to the necrotrophic fungus Botrytis cinerea. We demonstrated that plants undergo a deep transcriptional reprogramming upon elicitation with AA9 derived cellulose- or cello-oligosaccharides (AA9_COS). To decipher the specific effects of native and oxidized LPMO-generated AA9_COS, a pairwise comparison with cellobiose, the smallest non-oxidized unit constituting cellulose, is presented. Moreover, we identified two leucine-rich repeat receptor-like kinases, namely STRESS INDUCED FACTOR 2 and 4, playing a crucial role in signaling the AA9_COS-dependent responses such as camalexin production. Furthermore, increased levels of ethylene, jasmonic and salicylic acid hormones, along with deposition of callose in the cell wall was observed. Collectively, our data reveal that LPMOs might play a crucial role in plant-pathogen interactions.

Highlights

Lytic Polysaccharide Monooxygenases (LPMOs) are powerful redox enzymes able to oxidatively cleave recalcitrant polysaccharides
This family of enzymes is present on the necrotrophic pathogen B. cinerea, and they are selectively expressed during the infective process in Arabidopsis and none during growth on dextrose media (Supplementary Fig. 1)
The COS so obtained were purified with molecular filter (3 KDa cut-off), the absence of residual peptides was checked with sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE; Supplementary Fig. 2) and further characterized with high-performance anionexchange chromatography with pulsed amperometric detection (HPAEC-PAD; Fig. 1a)

Summary

Introduction

Lytic Polysaccharide Monooxygenases (LPMOs) are powerful redox enzymes able to oxidatively cleave recalcitrant polysaccharides. The plant cell wall is a dynamic structure mostly made up of high molecular weight polysaccharides, i.e., cellulose, hemicellulose, pectin and the heteropolymer lignin[1]. This complex aggregate confers structural integrity and physical protection to plant cells[1]. A novel family of CWDEs, the lytic polysaccharide monooxygenases (LPMOs), was discovered in 20106, and despite its potential role in plant pathogenicity[7], its biological significance in plant–pathogen interactions is still overlooked. The oxidative cleavage can take place at either C1- or C4-position of the pyranose ring This cleavage yields a full array of oxidized and native cellulose- or cello-oligosaccharides (COS), i.e., glucose polymers of variable degrees of polymerization (DP from 2 to 10), as well as their C1or C4-oxidized counterparts[6]. Lignin-derived phenols[10,11,12], photoactivated pigments such as chlorophyllin[9,13] and protein partners like cellobiose dehydrogenases (CDH)[14], are all possible electron donors for LPMO in vivo activity[15]

Methods

Results

Conclusion