Genetic Resistance Mechanisms in Southern Corn Rust
Summary
Southern corn rust, caused by the obligate biotrophic fungus Puccinia polysora, poses a serious threat to maize (Zea mays) production worldwide. Genetic resistance offers a sustainable means of control and comprises both race-specific and quantitative mechanisms. Race-specific resistance is often mediated by nucleotide-binding site–leucine-rich repeat (NBS-LRR) proteins that recognise discrete pathogen effectors and activate effector-triggered immunity. In contrast, quantitative resistance arises from multiple loci, each contributing partial protection, and is revealed through genome-wide association studies (GWAS) and quantitative trait locus (QTL) mapping. Advances in molecular marker technologies—such as simple sequence repeats (SSRs) and Kompetitive Allele Specific PCR assays—have accelerated marker-assisted selection and the pyramiding of resistance genes. Transcriptomic and proteomic analyses have elucidated defence signalling pathways, including pattern-triggered immunity and phytohormone networks. Population genetics studies, leveraging pathogen markers, inform on race diversity and migration, thereby guiding durable deployment of resistance genes. Integrating these genetic, genomic and molecular tools underpins the development of high-yielding, disease-resilient maize cultivars suited to diverse agro-climatic conditions.
Research from Nature Portfolio
Cloning of the maize NLR gene RppK alongside its cognate fungal effector, AvrRppK, has elucidated a clear gene-for-gene interaction in southern rust resistance. The AvrRppK sequence is highly conserved across Puccinia polysora isolates, enabling broad-spectrum efficacy of RppK when introgressed into maize lines without compromising agronomic performance under disease pressure. Functional assays showed that AvrRppK suppresses pattern-triggered immunity, emphasising the dynamic host–pathogen interplay. Complementing this, a de novo transcriptome assembly of P. polysora generated the first SSR marker resource for the pathogen, facilitating population genetic analyses. Polymorphic SSRs uncovered high genotypic diversity and clonal reproduction in regional pathogen populations, thereby informing resistance gene deployment strategies by revealing pathogen structure and migration patterns.
Genetic Resistance Mechanisms in Southern Corn Rust publication trend
The graph below shows the total number of articles in genetic resistance mechanisms in southern corn rust across all publications each year (not limited to Nature Index journals).
Technical terms
NBS-LRR (Nucleotide-Binding Site–Leucine-Rich Repeat): A class of intracellular plant immune receptors that detect specific pathogen effectors and trigger effector-triggered immunity.
SSR (Simple Sequence Repeat): Short tandem DNA repeats used as co-dominant molecular markers for genetic diversity, linkage and population studies.
GWAS (Genome-Wide Association Study): A population-based approach that scans the genome for statistical associations between genetic variants and phenotypic traits.
QTL (Quantitative Trait Locus): A chromosomal region harbouring one or more genes that influence the variation of a quantitative trait, such as disease resistance.
PAMP (Pathogen-Associated Molecular Pattern): Conserved microbial molecules recognised by host pattern recognition receptors, eliciting pattern-triggered immunity.
Marker-Assisted Selection: A breeding technique that employs molecular markers linked to desirable alleles to select individuals carrying favourable genes.
References
- Cloning southern corn rust resistant gene RppK and its cognate gene AvrRppK from Puccinia polysora. Nature Communications (2022).
- De novo transcriptome assembly, polymorphic SSR markers development and population genetics analyses for southern corn rust (Puccinia polysora). Scientific Reports (2021).
- Identification of RppSLN from an Elite Landrace: A Major Locus Conferring Resistance to Southern Corn Rust in Maize (Zea mays L.). Plants (2024).
- Identification of southern corn rust resistance QTNs in Chinese summer maize germplasm via multi-locus GWAS and post-GWAS analysis. Frontiers in Plant Science (2023).
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