Biology subjects

Verhage, A.

Publications and source records attributed to Verhage, A..

3 recordsLinked to original sources

bioRxiv2025

Asynchronous viral spread of two unrelated viruses determines Lettuce Big Vein Disease symptom development

Lettuce big-vein disease (LBVD) is a major disease affecting lettuce cultivation worldwide. LBVD is caused by two unrelated negative-stranded RNA viruses, that is, Mirafiori lettuce big-vein virus (MiLBVV) and Lettuce big-vein associated virus (LBVaV) both vectored by the soilborne fungus Olpidium virulentus. Despite extensive research, a synergistic effect between the two viruses has not been observed, while both viruses individually have been suggested to be the causal agent for the disease. By performing lettuce reinfections using a large soil sample collection carrying LBVD infested O. virulentus spores, the presence of LBVaV was consistently established in diseased lettuce heads, while MiLBVV infections were apparently less prevalent. Yet, aboveground infections with MiLBVV corresponded with strong disease symptoms. Strikingly, the spread of LBVaV from the root to shoot always preceded that of MiLBVV. The LBVaV systemic spread was highly synchronized between plants, while MiLBVV spread was always delayed and asynchronous. A pan-genome analysis revealed independent segment reassortments for both viruses indicative of mixed field infections over the sampled period. Yet, RNA segment abundance was highly conserved for both viruses between all re-infections, suggesting that segment abundance has a regulatory role for the two individual viruses, but that segment abundance is not impacted by the presence of the other two viruses. The pan-genome analysis also revealed different evolutionary rates of the viral ORFs suggesting that mutagenesis of certain ORFs compromises viral fitness and thus revealing a potential weak spot for both viruses. ImportanceLettuce big-vein disease (LBVD) is an important viral disease complex affecting lettuce cultivation worldwide. Here we reveal a synergistic interaction between the two principal associated segmented RNA viruses, Mirafiori lettuce big-vein virus (MiLBVV) and Lettuce big-vein associated virus (LBVaV). We show unequivocally that MiLBVV is the main virus responsible for severe disease symptoms in lettuce heads. Yet, MiLBVV root-to-shoot movement was in our conditions always preceded by LBVaV movement into the lettuce heads. Arguably, LBVaV thus facilitates the root-to-shoot movement of MiLBVV. Moreover, both viruses undergo segment reassortment increasing their genome plasticity and the reassortment events appeared to be independent events with mixed infections. Finally, we provide data that both viruses regulate gene expression via the copy number of their RNA segments, but that the genome formula does not change in dual infections. We thus provide evidence for a synergistic interaction needed for strong LBVD symptoms.

pathology↗

bioRxiv2023

A root-specific NLR network confers resistance to plant parasitic nematodes

Nucleotide-binding domain and leucine-rich repeat immune receptors (NLRs) confer disease resistance to a multitude of foliar and root parasites of plants. However, the extent to which NLR immunity is expressed differentially between plant organs is poorly known. Here, we show that a large cluster of tomato genes, which encodes the cyst and root-knot nematode disease resistance proteins Hero and MeR1 as well as the NLR-helper NRC6, exhibits nearly exclusive expression in the roots. This root-specific gene cluster emerged in Solanum species about 21 million years ago through gene duplication from the ancient NRC network of asterid plants. NLR-sensors in this gene cluster exclusively signal through NRC6 helpers to trigger the hypersensitive cell death immune response. These findings indicate that the NRC6 gene cluster has sub-functionalized from the larger NRC network to specialize for resistance against root pathogens, including cyst and root-knot nematodes. We propose that NLR gene clusters and networks have evolved organ-specific gene expression as an adaptation to particular parasites and to reduce the risk of autoimmunity.

plant biology↗

bioRxiv2019

Abscisic acid is essential for rewiring of jasmonic acid-dependent defenses during herbivory

Jasmonic acid (JA) is an important plant hormone in the regulation of defenses against chewing herbivores and necrotrophic pathogens. In Arabidopsis thaliana, the JA response pathway consists of two antagonistic branches that are regulated by MYC- and ERF-type transcription factors, respectively. The role of abscisic acid (ABA) and ethylene (ET) in the molecular regulation of the MYC/ERF antagonism during plant-insect interactions is still unclear. Here, we show that production of ABA induced in response to leaf-chewing Pieris rapae caterpillars is required for both the activation of the MYC-branch and the suppression of the ERF-branch during herbivory. Exogenous application of ABA suppressed ectopic ERF-mediated PDF1.2 expression in 35S::ORA59 plants. Moreover, the GCC-box promoter motif, which is required for JA/ET-induced activation of the ERF-branch genes ORA59 and PDF1.2, was targeted by ABA. Application of gaseous ET counteracted activation of the MYC-branch and repression of the ERF-branch by P. rapae, but infection with the ET-inducing necrotrophic pathogen Botrytis cinerea did not. Accordingly, P. rapae performed equally well on B. cinerea-infected and control plants, whereas activation of the MYC-branch resulted in reduced caterpillar performance. Together, these data indicate that upon feeding by P. rapae, ABA is essential for activating the MYC-branch and suppressing the ERF-branch of the JA pathway, which maximizes defense against caterpillars.

plant biology↗