Biology subjects

Thorpe, P. J.

Publications and source records attributed to Thorpe, P. J..

2 recordsLinked to original sources

bioRxiv2024

The origin, deployment, and evolution of a plant-parasitic nematode effectorome

Plant-parasitic nematodes constrain global food security. During parasitism, they secrete effectors into the host plant from two types of pharyngeal gland cells. These effectors elicit profound changes in host biology to suppress immunity and establish a unique feeding organ from which the nematode draws nutrition. Despite the importance of effectors in nematode parasitism, there has been no comprehensive identification and characterisation of the effector repertoire of any plant-parasitic nematode. To address this, we advance techniques for gland cell isolation and transcriptional analysis to define a stringent annotation of putative effectors for the cyst nematode Heterodera schachtii at three key life-stages. We define 659 effector gene loci: 293 "known" high-confidence homologs of plant-parasitic nematode effectors, and 366 "novel" effectors with high gland cell expression. In doing so we define a comprehensive "effectorome" of a plant-parasitic nematode. Using this effector definition, we provide the first systems-level understanding of the origin, deployment and evolution of a plant-parasitic nematode effectorome. The robust identification of the comprehensive effector repertoire of a plant-parasitic nematode will underpin our understanding of nematode pathology, and hence, inform strategies for crop protection.

plant biology↗

bioRxiv2023

A gene with a thousand alleles: the HYPer-variable effectors of plant-parasitic nematodes

Pathogens are engaged in a fierce evolutionary arms race with their host. The genes at the forefront of the engagement between kingdoms, including effectors and immune receptors, are part of diverse and highly mutable gene families. Even in this context, we discovered unprecedented variation in the HYPer-variable (HYP) effectors of plant-parasitic nematodes. We discovered single effector gene loci that can harbour potentially thousands of allelic variants. These alleles vary in the number, but principally in the organisation, of motifs within a central Hyper Variable Domain (HVD). Using targeted long-read sequencing, we dramatically expand the HYP repertoire of two plant-parasitic nematodes, Globodera pallida and G. rostochiensis, such that we can define distinct sets of species-specific "rules" underlying the apparently flawless genetic rearrangements. Finally, by analysing the HYP complement of 68 individual nematodes we made the unexpected finding that despite the huge number of alleles, most individuals are homozygous. Taken together, these data point to a novel mechanism of programmed genetic variation, termed HVD-editing, where alterations are locus-specific, strictly governed by rules, and can theoretically produce thousands of variants without errors.

genetics↗