Identification of bacterial wilt (erwinia tracheiphila) resistances in USDA melon collection

Authors: ACHARYA, BIMALA - Tennessee State University; MACKASMIEL, LUCAS - Tennessee State University; TAHERI, ALI - Tennessee State University; ONDZIGHI-ASSOUME, CHRISTINE - Tennessee State University; Weng, Yiqun; DUMENYO, CHARLES - Tennessee State University

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2021
Publication Date: 9/21/2021
Citation: Acharya, B., Mackasmiel, L., Taheri, A., Ondzighi-Assoume, C.A., Weng, Y., Dumenyo, C.K. 2021. Identification of bacterial wilt (erwinia tracheiphila) resistances in USDA melon collection. Plants. 10(9), 1972. https://doi.org/10.3390/plants10091972.
DOI: https://doi.org/10.3390/plants10091972

Interpretive Summary: Bacterial wilt (BW) is caused by the gram-negative bacterium, Erwinia tracheiphila (Et.), which is an important disease in melon production. There are also no effective pathogen-based disease management strategies as BW-infected plants ultimately die. Deployment of host resistance is a key component in any integrated pest management strategy. However, there is no widespread use of resistance in commercial melon production. The purpose of this study is to identify BW-resistant melon accessions in the USDA collection. We tested 118 melon accessions in two experiments in greenhouse conditions. Four-week-old seedlings were mechanically inoculated with the bacterial Et strain, Hca1-5N. We recorded the number of days to wilting of inoculated leaf (DWIL), days to wilting of whole plant (DWWP) and days to death of the plant (DDP). We identified four melon lines with high resistance to BW inoculation based on all three parameters. Microscopic observations identified differential pathogen growth dynamics between resistant and susceptible melon lines, which provides an insight into possible mechanisms of BW resistance in melon. This work provides novel BW resistance germplasm that could be used in commercial melon breeding for BW resistance. The information should also be useful for other cucurbit breeders, and for geneticists on exploring genetics of BW resistance in cucurbits.

Technical Abstract: Bacterial wilt (BW) caused by the Gram-negative bacterium, Erwinia tracheiphila (Et.), is an important disease in melon (Cucumis melo L.). BW-resistant commercial melon varieties are not widely available. There are also no effective pathogen-based disease management strategies, as BW-infected plants ultimately die. The purpose of this study is to identify BW-resistant melon accessions in the United States Department of Agriculture (USDA) collection. We tested 118 melon accessions in two inoculation trials under controlled environments. Four-week-old seed-lings of test materials were mechanically inoculated with the fluorescently (GFP) labeled or un-labeled E. tracheiphila strain, Hca1-5N. We recorded the number of days to wilting of inoculated leaf (DWIL), days to wilting of whole plant (DWWP) and days to death of the plant (DDP). We identified four melon lines with high resistance to BW inoculation based on all three parameters. Fluorescent microscopy was used to visualize the host colonization dynamics of labeled bacteria from the point of inoculation into petioles, stem and roots in resistant and susceptible melon accessions, which provides an insight into possible mechanisms of BW resistance in melon. The resistant melon lines identified from this study could be valuable resistance sources for breeding of BW resistance as well as the study of cucurbit—E. tracheiphila interactions.