Australasian Plant Pathology最新文献

Symptoms consistent with polyphagous shot hole borer (Euwallacea fornicatus) and Fusarium dieback (Fusarium euwallaceae), recognised as high priority environmental pests for Australia, were observed on a single box elder (Acer negundo) tree in Sydney, New South Wales, in March 2022 during routine forest biosecurity surveillance. Delimiting surveys were undertaken around the Sydney basin, extending radially from the original box elder, resulting in the detection of a further three box elder and one tuckeroo (Cupaniopsis anacardioides) with suspicious symptoms. Samples were taken from the five trees and associated beetles diagnosed using morphological and molecular methods. Associated Fusarium-like fungi were identified according to phylogenetic inference using regions of the internal transcribed spacer, as well as the translation elongation factor 1-α and RNA polymerase II genes. The tea shot hole borer, Euwallacea perbrevis, was identified along with its known fungal mutualist, Fusarium obliquiseptatum. This pair have been reported in Queensland on avocado (Persea americana) and tuckeroo, and there are unpublished records of E. perbrevis from northern NSW, but this is the first report of both species occurring simultaneously in NSW. The biosecurity response following the initial detection, including the establishment of an Incident Management Team, surveillance, diagnostics, and stakeholder engagement, is discussed. This paper highlights the importance of surveillance for early detection of invasive pests and biosecurity systems and processes for enabling a timely response.

Chilli leaf curl virus (ChiLCV) is a significant begomovirus that infects chili plants. To detect ChiLCV infection, a loop-mediated isothermal amplification (LAMP) assay was designed to be easy, quick, and efficient. The assay uses a set of five specific primers that target the coat protein gene (av1) of the target virus to detect the presence of the virus. The LAMP reaction amplifies the target gene within 45 min at 63 °C, with an 8mM dNTP concentration. This method showed no cross-reactivity with other tested begomoviruses that confirmed selective ChiLCV amplification. The sensitivity test revealed that LAMP was more sensitive than PCR. The LAMP assay displayed a remarkable detection limit of 10 fg/μL, which is superior than the PCR sensitivity of 10 pg/μL. Field sample validation yielded concordant results with PCR. This study introduces a cost-effective, and highly sensitive method for ChiLCV detection. Validation of LAMP with symptomatic leaves samples produced consistent results with PCR, demonstrating that the LAMP method could detect all infected samples.

Plant pathology researchers play a pivotal role in thought leadership and its translation to action regarding the recognition and demonstration of the value of Indigenous knowledge and science. For many scientists, navigating the space of Indigenous rights and perspectives is challenging. In pursuit of a cultural shift in research and development within the field of plant pathology, the 2019–2021 Management Committee of the Australasian Plant Pathology Society (APPS) undertook a review and modernization of the Society’s Constitution. The aim was to ensure its alignment with principles that foster inclusivity of Indigenous peoples in the development and implementation of relevant research projects impacting their communities. Additionally, a dynamic repository of guidelines and resources was compiled. These resources are designed to assist plant pathologists, while respecting and not superseding the guidance provided by local Indigenous researchers, practitioners, and advisors. The collective efforts of plant pathologists hold immense potential in championing Indigenous Peoples and their rights, steering the field toward a more inclusive and equitable future. This paper builds upon the thesis presented in the APPS Presidential Address at the Biennial APPS Conference in 2021, held virtually in lutruwita (Tasmania) on the unceded lands of the Palawa people. It underscores the potential impact when plant pathologists unite in advocating for Indigenous Peoples and their rightful place within the field.

Molecular diagnostics in combination with morphological identification is the method of choice for several cryptic microbial plant pathogens. For some diagnostic applications, traditional sequencing techniques can be time consuming, making them ill-suited for biosecurity incursion responses, where accurate results are needed in real time. More rapid next generation sequencing tools must be tested and compared with traditional methods to assess their utility in biosecurity applications. Here utilizing 95 samples infected with fungal pathogen Phyllosticta cavendishii, from a recent incursion in Australia, we compare species identification success using Internal Transcribed Spacer (ITS) gene barcode on conventional Sanger and Oxford Nanopore MinION sequencing platforms. For Sanger sequencing, the average pairwise identity percentage score between generated consensus sequences and P. cavendishii sequence from holotype material on NCBI database was 99.9% ± SE 0.0 whereas for MinION sequencing the average pairwise identity percentage was 99.1% ± SE 0.1. Relatively larger consensus sequences (mean 486 bp ± SE 2.4) were generated by Sanger sequencing compared to MinION sequencing (mean 435 bp ± SE 4.6). Our results confirm that both sequencing methods can reliably identify P. cavendishii. MinION sequencing, provided quicker results compared to Sanger sequencing and demonstrated diagnostic competence, with the added advantage of being portable, for front-line “point of incursion” biosecurity applications.

The Spanish bunch (Arachis hypogaea subsp fastigiata var vulgaris) cultivars of peanut are early maturing and extensively cultivated in India, but they suffer more from biotic and abiotic stresses than the Virginia types (Arachis hypogaea subsp hypogaea var hypogaea). The loss due to fungal foliar diseases viz., late leaf spot (LLS) and rust is an important constraint world over. Previous attempts to transfer these favourable traits have met with limited success. A high level of resistance is available in Virginia-type germplasm developed through interspecific hybridization. Systematic utilization of these resistance sources was initiated in improving locally adapted Spanish bunch varieties through extensive hybridization and development of large-scale segregating populations. Intensive evaluation of these breeding lines under high disease pressure led to the identification of early maturing, high-yielding and disease-resistant Spanish bunch variety, GPBD 4. Extensive testing and release for cultivation by the AICRIP system, widespread demonstrations on farmers’ fields and organized seed production under public systems led to its quick popularization, and it continued to benefit the farmers and consumers. An estimated economic benefit of INR 17.60 billion was derived from GPBD 4 for the period spanning from 2006 to 2022. GPBD 4 served as the source of resistance to breed at least five released varieties. The development of GPBD 4-based mapping populations, generation of phenotypic data, next-generation sequencing, mapping with molecular markers and narrowing down of genomic regions to identify the candidate genes governing disease resistance under collaborative efforts led to its immense utilization in marker-assisted breeding thereby refining the genomics-driven peanut improvement.

Abstract

Two standard area diagrams (SADs) were developed to quantify the severity of tomato early blight (EB), caused by Alternaria solani, on leaves and leaflets. The SADs were composed by sets of images with distinct EB severity for leaflets (0–40%) and leaves (0-46.4%). To validate the diagrams, 13 evaluators with no experience in quantifying the plant disease severity estimated EB severity by using a 50-image sample of tomato leaves and leaflets, first without SADs and then using the proposed SADs. The data were submitted to regression analysis and Lin’s concordance correlation coefficient, and the accuracy, precision, repeatability, and reproducibility of the estimates for EB severity were assessed. Based on the parameters of Lin’s coefficients and intraclass correlations, EB severity estimates were consistent and more reliable using SADs, improving evaluators’ performance. The diagrams proposed in this study improved the quantification of EB severity performed by 13 evaluators, increasing the accuracy, precision, and reliability of the estimates. Therefore, the proposed diagrams can be used in further studies on the epidemiology, resistance, and management strategies of this pathosystem.