Hannah Merrill and Jonathan Puglisi

“Developing KASP markers associated to avirulence genes in Puccinia striiformiss f. sp. triciti, the wheat stripe rust pathogen”

Hannah Merrill, Masters of Science candidate, Department of Plant Pathology, Dr. Xianming Chen’s Laboratory

Wheat is one of the most important crops produced in the United States. Stripe rust, caused by fungal pathogen Puccinia striiformis f. sp. triciti (Pst), can cause severe losses in yield and quality or cost multimillion dollars spent on control with fungicides (Chen 2014, 2020). Because of the economic impact that stripe rust has on the production of wheat, it is important to develop techniques for monitoring the pathogen populations. In our lab, Pst populations have been characterized by virulence testing on 18 Yr single-gene differentials every year (Liu et al. 2017; Wan and Chen 2014, Wan et al. 2016; Wang et al. 2022), and by simple sequence repeat (SSR) and secreted protein gene based single-nucleotide repeat (SP-SNP) markers (Bai et al. 2021, 2022; Li et al. 2019, 2020; Liu et al. 2021; Xia et al. 2016a, 2016b, 2017, 2018, 2020). However, a more efficient technique is needed to monitor virulence changes in the pathogen.
This goal of my study is to develop Kompetitive Allele Specific PCR (KASP) markers associated to avirulence genes of Pst to be used in monitoring virulence changes of the pathogen populations. The specific objectives are (1) design KASP markers based on SP-SNP markers associated to avirulence genes identified in our lab and test the KASP markers with a selected panel of Pst isolates; and (2) validate markers selected from Objective 1 with Pst collections of the recent years. Currently, progress has been made on selecting isolates, increasing urediniospores for DNA extraction, and learning the techniques in designing primers and testing KASP markers.

References:
Bai, Q., Wan, A. M., Wang, M. N., See, D. R., and Chen, X. M. 2021. Population diversity, dynamics, and differentiation of wheat stripe rust pathogen Puccinia striiformis f. sp. tritici from 2010 to 2017 and comparison with 1968 to 2009 in the United State. Front. Microbiol. 12:696835.
Bai, Q., Wang, M. N., Xia, C. J., See, D. R., and Chen, X. M. 2022. Identification of secreted protein gene-based SNP markers associated to virulence phenotypes of Puccinia striiformis f. sp. tritici, the wheat stripe rust pathogen. Int. J. Mol. Sci. 23:4114.

For more information on Hannah’s seminar please see the seminar announcement.

“Venturia inaequalis: The Importance, Epidemiology, and Management of a Destructive Apple Pathogen”
Jonathan Puglisi, Master of Science candidate,  Department of Plant Pathology, Dr. Achour Amiri Laboratory

Apple scab, caused by the ascomycete fungus Venturia inaequalis, is one of the most common and devastating diseases of apple in temperate regions worldwide. The earliest depictions of apples with scab-like symptoms are found in paintings from the 15th and 16th centuries, but Spilocaea pomi, the anamorph of V. inaequalis was first documented by Swedish scientist Elias Fries in 1819. Apple scab infection produces lesions on leaves, blossoms and fruit, and can cause fruit drop and defoliation under high disease pressure conditions. Repeated defoliation events due to apple scab infection will increase the host tree’s susceptibility to environmental and insect stressors. Trees infected in the previous seasons may also show reduced and late-returning bloom. V. inaequalis infection occurs in the early spring when windborne sexual spores (ascospores) are released after rainfall. Lesions resulting from infection by ascospores produce secondary inoculum (conidia), which are transmitted to apple blossoms, fruit, and leaves by wind or rain. Disease management relies primarily on planting of scab-resistant apple and crab apple varieties, and fungicide application. The extensive usage of fungicides to control apple scab has resulted in the evolution of multi-fungicide resistance in V. inaequalis populations. The disease symptoms of apple scab, which result in unmarketable fruit and systemic tree damage, in combination with its global distribution and multi-fungicide resistance, solidify it as one of the most economically important diseases of apple.

References:
Belete, T. and Boyraz, N. 2017. Critical Review on Apple Scab (Venturia inaequalis) Biology, Epidemiology, Economic Importance, Management and Defense Mechanisms to the Causal Agent. J Plant Physiol Pathol, 5:2. doi: 10.4172/2329-955X.1000166.
Chapman, K.S., Sundin, G.W., Beckerman, J.L. 2011. Identification of Resistance to Multiple Fungicides in Field populations of Venturia inaequalis.
Gauthier, N. 2018. Apple scab. The Plant Health Instructor. doi: 10.1094/PHI-I-2000-1005-01.
Jha, G., Thakur, K., and Thakur, P. 2009. The Venturia Apple Pathosystem: Pathogenicity Mechanisms and Plant Defense Responses. J Biomed Biotechnol. 680160. doi: 10.1155/2009/680160.

For more information on Jonathan’s seminar please see the seminar announcement.