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ARS Home » Southeast Area » Charleston, South Carolina » Vegetable Research » Research » Publications at this Location » Publication #348635

Research Project: Biology, Etiology and Host Resistance in Vegetable Crops to Diseases and Nematodes

Location: Vegetable Research

Title: Broad resistance to U.S. powdery mildew isolates in newly developed watermelon germplasm lines

item Kousik, Chandrasekar - Shaker
item MANDEL, MIHIR - Oak Ridge Institute For Science And Education (ORISE)
item Ikerd, Jennifer
item Adkins, Scott
item Turechek, William

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 7/29/2018
Publication Date: 10/15/2018
Citation: Kousik, C.S., Mandal, M.K>, Ikerd, J., Adkins, S., and Turechek, W.W. 2018. Broad resistance to U.S. powdery mildew isolates in newly developed watermelon germplasm lines. (Abstr.) Phytopathology 108:S1.173.

Interpretive Summary:

Technical Abstract: Powdery mildew (PM) of watermelon caused by Podosphaera xanthii has been occurring more frequently in commercial fields in recent years and is known to result in significant yield reduction. However, commercial watermelon cultivars with PM resistance are lacking. Resistance is available in non-edible pollenizers and in U.S. Plant Introductions (PI). We developed PM resistant red-fleshed watermelon germplasm lines for use in breeding programs after six generations (S6) of phenotyping and selection from PI. The lines USVL608-PMR, USVL313-PMR, USVL255-PMR, USVL585-PMR, USVL531-MDR and USVL278-PMR exhibit high levels of resistance in hypocotyls, cotyledons and true leaves to a local isolate of P. xanthii compared to watermelon cultivars Mickey Lee and a susceptible watermelon line USVL677-PMS on which abundant development of conidia was observed. In summer and fall field trials in 2017, these lines had <2% of leaf area infected compared to >70% of USVL677-PMS. Detached true leaves of these lines placed in petri-plates were sprayed with a conidial suspension (10^5 conidia/ml in 0.02% tween 20) of P. xanthii isolates collected from different states (SC, FL, GA, NY and CA). All the above watermelon germplasm lines were resistant to isolates from different states compared to USVL677-PMS on which severe PM (>70%) was observed. Watermelon lines with broad resistance to PM will be good sources for incorporating resistance in commercially acceptable cultivars for use across U.S.