Watermelon germplasm lines: USVL608-PMR, USVL255-PMR, USVL313-PMR and USVL585-PMR with broad resistance to powdery mildew

Authors: Kousik, Chandrasekar - Shaker; Ikerd, Jennifer; MANDAL, MIHIR - Oak Ridge Institute For Science And Education (ORISE); Adkins, Scott; Turechek, William

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2018
Publication Date: 8/24/2018
Citation: Kousik, C.S., Ikerd, J.L., Mandal, M., Adkins, S.T., Turechek, W. 2018. Watermelon germplasm lines: USVL608-PMR, USVL255-PMR, USVL313-PMR and USVL585-PMR with broad resistance to powdery mildew. HortScience. 53(8):1212-1217. https://doi.org/10.21273/HORTSCI12979-18.
DOI: https://doi.org/10.21273/HORTSCI12979-18

Interpretive Summary: Watermelon is an important vegetable crop grown in 44 states in the U.S.A. Many diseases and pests attack watermelon seedlings and plants and reduce their yield resulting in monetary loss for growers. One such disease, known as powdery mildew can infest watermelon seedlings and can cause reduced vigor or death of seedlings and also result in yield reduction in the field. Growers generally spray expensive pesticides to manage this disease. ARS scientists in Charleston, SC, have developed four watermelon germplasm lines (USVL608-PMR, USVL313-PMR, USVL255-PMR and USVL585-PMR) with resistance to powdery mildew. These resistant germplasm lines can be used by private and public sector plant breeders to develop watermelon varieties and breeding lines with resistance to powdery mildew. Development of varieties with resistance to powdery mildew will help reduce pesticide use and allow watermelon growers to produce a healthy crop.

Technical Abstract: USVL608-PMR (powdery mildew resistant), USVL313-PMR, USVL255-PMR and USVL585-PMR are watermelon (Citrullus lanatus var. lanatus (Thunb.) Matsum. & Nakai) germplasm lines that exhibit high levels of resistance to powdery mildew (PM) caused by Podosphaera xanthii (Castagne) U. Braun & Shishkoff (syn. Sphaerotheca fuliginea). Specifically, the hypocotyls, cotyledons and true leaves of these four PMR lines are highly resistant to powdery mildew compared to the susceptible watermelon line USVL677-PMS or cultivar Mickey Lee on which severe powdery mildew and abundant development of conidia can be observed. The true leaves of these four PMR lines were also resistant to P. xanthii isolates from other states including; California, Florida, Georgia, New York, and South Carolina. Each of these four PMR lines are highly uniform for growth characteristics, fruit size, shape and color with red to pink flesh and brix content ranging from 6 to 8. Currently, commercial watermelon cultivars with powdery mildew resistance are rare. Hence, USVL608-PMR, USVL313-PMR, USVL255-PMR and USVL585-PMR will be useful sources for incorporating resistance in commercially acceptable cultivars. These lines are fertile and can easily be crossed with commercial watermelon cultivars to develop new breeding populations.