Apoplastic recognition of multiple candidate effectors from the wheat pathogen Zymoseptoria tritici in the nonhost plant Nicotiana benthamiana

The fungus Zymoseptoria tritici is a strictly apoplastic, host-specific pathogen of wheat leaves and causal agent of septoria tritici blotch (STB) disease. All other plants are considered nonhosts, but the mechanism of nonhost resistance (NHR) to Z. tritici has not been addressed previously. We sought to develop Nicotiana benthamiana as a system to study NHR against Z. tritici. Fluorescence microscopy and quantitative reverse transcription polymerase chain reactions were used to establish the interaction between Z. tritici and N. benthamiana. Agrobacteriummediated transient expression was used to screen putative Z. tritici effector genes for recognition in N. benthamiana, and virus-induced gene silencing (VIGS) was employed to determine the role of two receptor-like kinases (RLKs), NbBAK1 and NbSOBIR1, in Z. tritici effector recognition. Numerous Z. tritici putative effectors (14 of 63 tested) induced cell death or chlorosis in N. benthamiana. For most, phenotypes were light-dependent and required effector secretion to the leaf apoplastic space. Moreover, effector-induced host cell death was dependent on NbBAK1 and NbSOBIR1. Our results indicate widespread recognition of apoplastic effectors from a wheat-infecting fungal pathogen in a taxonomically distant nonhost plant species presumably by cell surface immune receptors. This suggests that apoplastic recognition of multiple nonadapted pathogen effectors may contribute to NHR

Indirect Evidence Based on Mating-Type Ratios for the Role of Sexual Reproduction in European and Chinese Populations of <i>Plenodomus biglobosus</i> (Blackleg of Oilseed Rape)

Blackleg (Phoma) disease, caused by the ascomycete fungi Plenodomus biglobosus and P. lingam, threatens oilseed rape (OSR; Brassica napus) crops internationally. In many parts of the world, both species co-occur, but in China only P. biglobosus has so far been reported. Plenodomus biglobosus reproduces asexually (pycnidiospores), but also sexually (pseudothecia-yielding ascospores), via a heterothallic mating system requiring MAT1-1 and MAT1-2 genotypes. However, the roles of airborne ascospore inoculum in driving blackleg disease outbreaks in China are less well understood compared to elsewhere in the world. This is despite the very different agronomic cropping practices in parts of China, in which paddy rice and OSR are often grown in rotation; OSR stubble is often submerged under water for long periods potentially affecting pseudothecial development. Here, we indirectly investigate the potential role of sexual reproduction by developing new polymerase chain reaction (PCR) -based mating-type diagnostics for P. biglobosus and subsequently screening an international collection of 59 European and 157 Chinese isolates. Overall, in both Europe and China, P. biglobosus mating types did not deviate from a 1:1 ratio, such as is generally thought to occur under frequency-dependent selection in sexually reproducing pathogen populations. Both mating types were balanced in all the individual European countries tested (Austria, France, Poland, UK). Conversely, in China, mating types were only balanced in the eastern region; in the northern and southwestern regions there were skewed ratios, more typical of predominantly asexual reproduction, towards MAT1-1 and MAT1-2, respectively. The implications of these findings and future research directions for improved understanding of P. biglobosus epidemiology on OSR, particularly in China, are considered

Fungal communities including plant pathogens in near surface air are similar across northwestern Europe

Information on the diversity of fungal spores in air is limited, and also the content of airborne spores of fungal plant pathogens is understudied. In the present study, a total of 152 air samples were taken from rooftops at urban settings in Slagelse, DK, Wageningen NL, and Rothamsted, UK together with 41 samples from above oilseed rape fields in Rothamsted. Samples were taken during 10-day periods in spring and autumn, each sample representing 1 day of sampling. The fungal content of samples was analyzed by metabarcoding of the fungal internal transcribed sequence 1 (ITS1) and by qPCR for specific fungi. The metabarcoding results demonstrated that season had significant effects on airborne fungal communities. In contrast, location did not have strong effects on the communities, even though locations were separated by up to 900 km. Also, a number of plant pathogens had strikingly similar patterns of abundance at the three locations. Rooftop samples were more diverse than samples taken above fields, probably reflecting greater mixing of air from a range of microenvironments for the rooftop sites. Pathogens that were known to be present in the crop were also found in air samples taken above the field. This paper is one of the first detailed studies of fungal composition in air with the focus on plant pathogens and shows that it is possible to detect a range of pathogens in rooftop air samplers using metabarcoding

The impact of subspecialization and dermatoscopy use on accuracy of melanoma diagnosis among primary care doctors in Australia

Background: Dermatoscopy improves accuracy of melanoma diagnosis, but the impact of subspecialization in skin cancer practice among general practitioners on melanoma diagnostic accuracy is not known

Efficient qPCR estimation and discrimination of airborne inoculum of Leptosphaeria maculans and L. biglobosa, the causal organisms of phoma leaf spotting and stem canker of oilseed rape : qPCR detection of Leptosphaeria airborne inoculum

© 2023 Society of Chemical Industry. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1002/ps.7800BACKGROUND: Detection of the inoculum of phytopathogens greatly assists in the management of diseases, but is difficult for pathogens with airborne fungal propagules. Here, we present experiments to determine the abundance and distribution frequencies of the ascospores of Leptosphaeria (Plenodomus) species that were collected on the tapes of volumetric Hirst-type traps near oilseed rape fields in Poznan, Poland and Harpenden, UK. Fungal detection and species discrimination were achieved using a SYBR-Green quantitative polymerase chain reaction (qPCR) with two different pairs of primers previously reported to differentiate Leptosphaeria maculans (Plenodomus lingam) or L. biglobosa (P. biglobosus). RESULTS: Detection was successful even at fewer than five spores per m 3 of air. The primer pairs differed in the correlation coefficients obtained between DNA yields and the daily abundance of ascospores that were quantified by microscopy on duplicate halves of the spore trap tapes. Important differences in the specificity and sensitivity of the published SYBR-Green assays were also found, indicating that the Liu primers did not detect L. biglobosa subclade ‘canadensis’, whereas the Mahuku primers detected L. biglobosa subclade ‘canadensis’ and also the closely related Plenodomus dezfulensis. CONCLUSIONS: Comparisons confirmed that application of qPCR assays to spore trap samples can be used for the early detection, discrimination and quantification of aerially dispersed L. maculans and L. biglobosa propagules before leaf spot symptoms are visible in winter oilseed rape fields. The specificity of the primers must be taken into consideration because the final result will greatly depend on the local population of the pathogen.Peer reviewe

Cognitive-Motor Interference During Functional Mobility After Stroke: State of the Science and Implications for Future Research

Cognitive-motor interference (CMI) is evident when simultaneous performance of a cognitive task and a motor task results in deterioration in performance in one or both of the tasks, relative to performance of each task separately. The purpose of this review is to present a framework for categorizing patterns of CMI and to examine the specific patterns of CMI evident in published studies comparing single-task and dual-task performance of cognitive and motor tasks during gait and balance activities after stroke. We also examine the literature for associations between patterns of CMI and history of falls, as well as evidence for the effects of rehabilitation on CMI after stroke. Overall, this review suggests that during gait activities with an added cognitive task, people with stroke are likely to demonstrate significant decrements in motor performance only (cognitive-related motor interference) or decrements in both motor and cognitive performance (mutual interference). In contrast, patterns of CMI were variable among studies examining balance activities. Comparing people post-stroke with and without a history of falls, patterns and magnitude of CMI were similar for fallers and non-fallers. Longitudinal studies suggest that conventional rehabilitation has minimal effects on CMI during gait or balance activities. However, early phase pilot studies suggest that dual-task interventions may reduce CMI during gait performance in community-dwelling stroke survivors. It is our hope that this innovative and critical examination of the existing literature will highlight the limitations in current experimental designs and inform improvements in the design and reporting of dual-task studies in stroke