Comparative secretome analysis of Rhizoctonia solani isolates with different host ranges reveals unique secretomes and cell death inducing effectors

Abstract

Rhizoctonia solani is a fungal pathogen causing substantial damage to many of the worlds’ largest food crops including wheat, rice, maize and soybean. Despite impacting global food security, little is known about the pathogenicity mechanisms employed by R. solani. To enable prediction of effectors possessing either broad efficacy or host specificity, a combined secretome was constructed from a monocot specific isolate, a dicot specific isolate and broad host range isolate infecting both monocot and dicot hosts. Secretome analysis suggested R. solani employs largely different virulence mechanisms to well-studied pathogens, despite in many instances infecting the same host plants. Furthermore, the secretome of the broad host range AG8 isolate may be shaped by maintaining functions for saprophytic life stages while minimising opportunities for host plant recognition. Analysis of possible co-evolution with host plants and in-planta up-regulation in particular, aided identification of effectors including xylanase and inhibitor I9 domain containing proteins able to induce cell death in-planta. The inhibitor I9 domain was more abundant in the secretomes of a wide range of necrotising fungi relative to biotrophs. These findings provide novel targets for further dissection of the virulence mechanisms and potential avenues to control this under-characterised but important pathogen.

Understanding sheath blight resistance in rice: the road behind and the road ahead

“…cytochrome C oxidase assembly protein CtaG/cox11 domain, glycosyltransferase GT family 2 domain and peptidase inhibitor I9 domain) of R. solani AG1-1A were validated that could trigger crop defence responses in the form of cell death phenotype . Similarly, inhibitor I9 containing proteins have been abundantly detected in the predicted secretome of ShB pathogen (Anderson et al, 2017). In a recent genomic analysis of two virulent Indian strains of R. solani AG1-1A, several putative candidate effectors such as histone acetyltransferase, histone deacetylase inhibitor, MDR transporter, O-antigen biosynthesis protein, O-methyl sterigmatocystin oxidoreductase, polygalacturonase and pectin lyase have been predicted .…”

Identification of the Novel Effector RsIA_NP8 in Rhizoctonia solani AG1 IA That Induces Cell Death and Triggers Defense Responses in Non-Host Plants

“…Unlike biotrophs, which absorb nutrients from the cells and tissue of living hosts for colonization and growth, necrotrophs kill host cells and take nutrients from dead plant tissue (Schulmeyer and Yahr, 2017). However, all of these pathogens have a characteristic in common-effectors, which play crucial roles in promoting pathogen infection and suppressing host defenses (Koeck et al, 2011;Kabbage et al, 2015;Anderson et al, 2017). Although effectors are important, only a small proportion of the many proteins secreted by pathogens have been identified as effectors.…”

“…The effectors SnToxA and SnTox3 recognize PR-1-PR-5 and PR-1-1, respectively, and play a crucial role in Parastagonospora nodorum-host interactions (Lu et al, 2014;Breen et al, 2016). Several effectors have been studied in species of R. solani, such as AGLIP1 (Li et al, 2019), RsLysM (Dölfors et al, 2019), and RSAG8_06778 (Anderson et al, 2017), in R. solani AG1 IA R. solani AG2-2IIIB, and R. solani AG8, respectively. AGLIP1 encodes a protein of 302 amino acids (aa) to trigger non-host and host cell death and affect the host immune response (Li et al, 2019).…”

TheRhizoctonia solaniRsLysM and RsRlpA effector proteins contribute to virulence by suppressing chitin-triggered immunity and hypersensitive response

“…The availability of R. solani AG2-2IIIB genome (Wibberg et al, 2016a, b) gave us the advantage to select the most promising candidate effectors. The AG2-2IIIB isolate secretes an elevated number of proteins as compared to other sequenced AG isolates with known genomes (Anderson et al, 2017;Wibberg et al, 2016b), possibly because of adaptation to hosts. Among the putative secreted ones, more than 100 have been annotated as candidate effectors, (Wibberg et al, 2016b).…”

“…Genomic data are presently available from five different R. solani strains with cereal and dicot plant hosts (Cubeta et al, 2014;Hane et al, 2014;Wibberg et al, 2013Wibberg et al, , 2016aZheng et al, 2013). In an AG8 strain, attacking both monocots and dicots, a xylanase and a protease inhibitor I9 induced cell death when expressed in Nicotiana benthamiana (Anderson et al, 2017).…”