Pathogenic Mechanisms of Rhizoctonia Species in Crop Systems

Rhizoctonia species are soil-borne fungi that cause widespread root rot, damping-off and stem canker in many staple crops. Infection initiates when hyphae or germinating sclerotia adhere to root surfaces, differentiate penetration structures and secrete a suite of cell wall-degrading enzymes such as pectinases and glucanases. These enzymes, together with necrosis-inducing effectors, facilitate host tissue maceration and nutrient release. Anastomosis groups (AGs), defined by hyphal fusion compatibility, govern host specificity and determine the spectrum of susceptible crops. Sclerotia act as long-term survival structures, enduring adverse conditions and germinating when host roots are nearby. Recent genomic analyses have uncovered clusters of pathogenicity genes that regulate effector secretion and detoxification of plant defence metabolites. The interplay between AG diversity, enzyme repertoires and effector profiles underpins disease severity. In agricultural practice, integrated management combines crop rotation, resistant cultivars, soil amendments and biocontrol agents to disrupt pathogen survival and infection cycles.

Research from Nature Portfolio

Recent morphological and phylogenetic work has identified a distinct trinucleate subgroup within AG-E isolates. Detailed nuclear counts and hyphal measurements under fluorescence microscopy revealed isolates with consistently three nuclei per cell, facilitating rapid preliminary identification of AG-E-3n strains. This classification refines diagnostic protocols and aids in monitoring the distribution of this understudied AG. Separately, surveys of tomato-infecting isolates have defined the prevalence of multiple AGs, notably AG-3-PT, AG-2-1 and AG-5, in diverse growing regions. Molecular typing of the ITS region coupled with hyphal interaction tests confirmed group assignments, and pathogenicity assays under greenhouse conditions validated their virulence profiles. These findings emphasise the need for region-specific management strategies and for breeding programmes to target the most aggressive AG lineages.

Pathogenic Mechanisms of Rhizoctonia Species in Crop Systems publication trend

The graph below shows the total number of articles in pathogenic mechanisms of rhizoctonia species in crop systems across all publications each year (not limited to Nature Index journals).

Technical terms

Anastomosis group (AG): A classification of Rhizoctonia isolates based on hyphal fusion compatibility and genetic relatedness.

Sclerotium: A compact, multicellular fungal survival structure that withstands environmental stresses and germinates to initiate infection.

Hyphal anastomosis: The process by which fungal hyphae fuse, enabling genetic exchange and defining AG status.

Necrotroph: A pathogen that kills host tissue and derives nutrients from the dead cells.

Effector: A secreted protein or metabolite that manipulates host cell structure or immunity to facilitate infection.

ITS region: The internal transcribed spacer of ribosomal DNA used as a molecular barcode for fungal identification.

References

1. Exploration of resistance level against Black Scurf caused by Rhizoctonia solani in different cultivars of potato. Plant Stress (2024).
2. Global distribution, traditional and modern detection, diagnostic, and management approaches of Rhizoctonia solani associated with legume crops. Frontiers in Microbiology (2023).
3. Biological characteristics and metabolic phenotypes of different anastomosis groups of Rhizoctonia solani strains. BMC Microbiology (2024).
4. Characterization of three-nucleate Rhizoctonia AG-E based on their morphology and phylogeny. Scientific Reports (2023).
5. Anastomosis Groups of Rhizoctonia solani associated with tomato foot rot in Pothohar Region of Pakistan. Scientific Reports (2019).