Biology subjects

Henry, P. M.

Publications and source records attributed to Henry, P. M..

3 recordsLinked to original sources

bioRxiv2024

Population genomics of Macrophomina spp. reveals cryptic host specialization and evidence for meiotic recombination

Knowledge of the factors structuring populations of pathogenic fungi is fundamental to disease management efforts and basic biology. High-quality short-read sequence data were obtained for 463 Macrophomina spp. isolates collected from 91 host plant species and soil in 23 countries. Analyses revealed high diversity, admixture, and equal mating type ratios suggesting on-going recombination. Although most tested isolates could asymptomatically colonize strawberry, only isolates from a single phylogroup caused disease. In addition to strawberry, evidence for host specialization was discovered for soybean, demonstrating this broad host range pathogen contains phylogroups with cryptic specialization. Geography x isolate genotype associations were weak, suggesting these species were frequently trafficked between regions. Re-analysis using genomic data supported current species boundaries, and new molecular markers were designed to specifically identify each species. Contrary to expectations, M. phaseolina should be considered a species with both specialist and generalist populations for which meiosis can increase genetic diversity.

genomics↗

bioRxiv2021

Novel Fusarium Wilt Resistance Genes Uncovered in the Wild Progenitors and Heirloom Cultivars of Strawberry

Fusarium wilt, a soilborne disease caused by Fusarium oxysporum f. sp. fragariae, poses a significant threat to strawberry (Fragaria x ananassa) production in many parts of the world. This pathogen causes wilting, collapse, and death in susceptible genotypes. We previously identified a dominant gene (FW1) on chromosome 2B that confers resistance to race 1 of the pathogen and hypothesized that gene-for-gene resistance to Fusarium wilt was widespread in strawberry. To explore this, a genetically diverse collection of heirloom and modern cultivars and wild octoploid ecotypes were screened for resistance to Fusarium wilt races 1 and 2. Here we show that resistance to both races is widespread and that resistance to race 1 is mediated by dominant genes (FW1, FW2, FW3, FW4, and FW5) on three non-homoeologous chromosomes (1A, 2B, and 6B). The resistance proteins encoded by these genes are not yet known; however, plausible candidates were identified that encode pattern recognition receptor or other proteins known to mediate gene-for-gene resistance in plants. High-throughput genotyping assays for SNPs in linkage disequilibrium with FW1-FW5 were developed to facilitate marker-assisted selection and accelerate the development of race 1 resistant cultivars. This study laid the foundation for identifying the genes encoded by FW1-FW5, in addition to exploring the genetics of resistance to race 2 and other races of the pathogen, as a precaution to averting a Fusarium wilt pandemic. Key MessageSeveral race-specific resistance genes were identified and rapidly deployed via marker-assisted selection to develop strawberry cultivars resistant to Fusarium wilt, a devastating soil-borne disease.

plant biology↗

bioRxiv2018

Persistence of Fusarium oxysporum f. sp. fragariae in soil through asymptomatic colonization of rotation crops

Asymptomatic plant colonization is hypothesized to enhance persistence of pathogenic forms of Fusarium oxysporum in the absence of a susceptible host. However, a correlation between pathogen populations on living plant tissues and soilborne populations after tillage has not been demonstrated. Living and dead tissues of broccoli, lettuce, spinach, wheat, cilantro, raspberry, and strawberry plants inoculated with Fusarium oxysporum f. sp. fragariae (the cause of Fusarium wilt of strawberry) were assayed to quantify the incidence of infection and extent of colonization by this pathogen. All crops could be infected by F. oxysporum f. sp. fragariae, but the extent of colonization varied between plant species. Pathogen population densities on non-living crown tissues incorporated into the soil matrix were typically greater than those observed on living tissues. Crop-dependent differences in the inoculum density of F. oxysporum f. sp. fragariae in soil were only observed after decomposition of crop residue. Forty-four weeks after plants were incorporated into the soil, F. oxysporum f. sp. fragariae soil population densities were positively correlated with population densities on plant tissue fragments recovered at the same timepoint. Results indicate that asymptomatic colonization can have a significant, long-term impact on soilborne populations of Fusarium wilt pathogens. Cultural practices, such as crop rotation, should be leveraged to favor pathogen population decline by planting hosts that do not support extensive population growth on living or decomposing tissues.

microbiology↗