Biology subjects

Clay, K.

Publications and source records attributed to Clay, K..

4 recordsLinked to original sources

bioRxiv2021

Diversification of ergot alkaloids and heritable fungal symbionts in morning glories

Heritable microorganisms play critical roles in life cycles of many macro-organisms but their prevalence and functional roles are unknown for most plants. Bioactive ergot alkaloids produced by heritable Periglandula fungi occur in some morning glories (Convolvulaceae), similar to ergot alkaloids in grasses infected with related fungi. Ergot alkaloids have been of longstanding interest given their toxic effects, psychoactive properties, and medical applications. Here we show that ergot alkaloids are concentrated in four morning glory clades exhibiting differences in alkaloid profiles and are more prevalent in species with larger seeds than those with smaller seeds. Further, we found a phylogenetically-independent, positive correlation between seed mass and alkaloid concentrations in symbiotic species. Our findings suggest that heritable symbiosis has diversified among particular clades by vertical transmission through seeds combined with host speciation, and that ergot alkaloids are particularly beneficial to species with larger seeds. Our results are consistent with the defensive symbiosis hypothesis where bioactive ergot alkaloids from Periglandula symbionts protect seeds and seedlings from natural enemies, and provide a framework for exploring microbial chemistry in other plant-microbe interactions.

plant biology↗

bioRxiv2021

Lizard feeding enhances Ixodes pacificus vector competency

A vectors susceptibility and ability to transmit a pathogen-- termed vector competency--determines disease outcomes, yet the ecological factors influencing tick vector competency remain largely unknown. Ixodes pacificus, the vector of Borrelia burgdorferi (Bb) in the western U.S., feeds on rodents, birds, and lizards. While rodents and birds are reservoirs for Bb and infect juvenile ticks, lizards are Bb-refractory. Despite I. pacificus feeding on a range of hosts, it is undetermined how larval host bloodmeal identity affects future nymphal vector competency. We experimentally evaluate the influence of larval host bloodmeal on Bb acquisition by nymphal I. pacificus. Larval I. pacificus were fed on either lizards or mice and after molting, nymphs were fed on Bb-infected mice. We found that lizard-fed larvae were significantly more likely to become infected with Bb during their next bloodmeal than mouse-fed larvae. We also conducted the first RNA-seq analysis on whole-bodied I. pacificus and found significant upregulation of antioxidants and antimicrobial peptides in the lizard-fed group. Our results indicate that the lizard bloodmeal significantly alters vector competency and gene regulation in ticks, highlighting the importance of host bloodmeal identity in disease transmission and upends prior notions about the role of lizards in Lyme disease transmission.

ecology↗

bioRxiv2021

Novel genome characteristics contribute to the invasiveness of Phragmites australis (common reed)

The rapid invasion of the non-native Phragmites australis (Poaceae, subfamily Arundinoideae) is a major threat to native ecosystems in North America. We describe a 1.14 Gbp reference genome for P. australis and compare invasive (ssp. australis) and native (ssp. americanus) genotypes collected across the Laurentian Great Lakes to deduce genomic bases driving its invasive success. We report novel genomic features including a lineage-specific whole genome duplication, followed by gene loss and preferential retention of genes associated with transcription factors and regulatory functions in the remaining duplicates. The comparative transcriptomic analyses revealed that genes associated with biotic stress and defense responses were expressed at a higher basal level in invasive genotypes, but the native genotypes showed a stronger induction of defense responses following fungal inoculation. The reference genome and transcriptomes, combined with previous ecological and environmental data, support the development of novel, genomics-assisted management approaches for invasive Phragmites.

plant biology↗

bioRxiv2021

Invasive grass litter suppresses native species and promotes disease

Plant litter can alter ecosystems and promote plant invasions by changing resource acquisition, depositing toxins, and transmitting microorganisms to living plants. Transmission of microorganisms from invasive litter to live plants may gain importance as invasive plants accumulate pathogens over time since introduction. It is unclear, however, if invasive plant litter affects native plant communities by promoting disease. Microstegium vimineum is an invasive grass that suppresses native populations, in part through litter production, and has accumulated leaf spot diseases since its introduction to the U.S. In a greenhouse experiment, we evaluated how M. vimineum litter and accumulated pathogens mediated resource competition with the native grass Elymus virginicus. Resource competition reduced biomass of both species and live M. vimineum increased disease incidence on the native species. Microstegium vimineum litter also promoted disease on the native species, suppressed establishment of both species, and reduced biomass of M. vimineum. Nonetheless, interference competition from litter had a stronger negative effect on the native species, increasing the relative abundance of M. vimineum. Altogether, invasive grass litter suppressed both species, ultimately favoring the invasive species in competition, and increased disease incidence on the native species.

ecology↗