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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Publications at this Location » Publication #308966

Research Project: Genetic Enhancement of Allium, Cucumis, and Daucus Germplasm

Location: Vegetable Crops Research

Title: Epicuticular waxes on onion leaves and associated resistance to onion thrips

Author
item Damon, Steve - University Of Wisconsin
item Groves, Russell - University Of Wisconsin
item Havey, Michael

Submitted to: National Allium Research Conference
Publication Type: Abstract Only
Publication Acceptance Date: 11/5/2014
Publication Date: 12/5/2014
Citation: Damon, S., Groves, R., Havey, M.J. 2014. Epicuticular waxes on onion leaves and associated resistance to onion thrips [abstract]. National Allium Research Conference. Paper No. III-3.

Interpretive Summary:

Technical Abstract: Natural variation exists for amounts and types of epicuticular waxes on onion foliage. Wild-type onion possesses copious amounts of these waxes and is often referred to as “waxy”. The recessively inherited “glossy” phenotype has significantly less wax relative to waxy types and shows resistance to onion thrips (Thrips tabaci), but is vulnerable to spray damage, foliar pathogens, and excessive transpiration. Phenotypes visually intermediate between waxy and glossy exist in onion and are referred to as “semi-glossy”. Scanning electron microscopy revealed copious wax crystals on the leaf surface of waxy onion, with fewer on semi-glossy and none on glossy leaves. Gas-chromatography-mass-spectrometry (GCMS) identified ketones, alkanes, and fatty alcohols on the leaf surface of waxy onion, with the ketone hentriacontanone-16 as the most prevalent. A segregating family from the cross of waxy and semi-glossy onions demonstrated that amounts of hentriacontanone-16 were controlled by a region on chromosome 5 and concentrations of several fatty alcohols by a region on chromosome 2. Because lower amounts of epicuticular waxes are recessively inherited, single nucleotide polymorphisms tagging regions on chromosomes 2 and 5 were identified for marker-assisted breeding to vary amounts and types of epicuticular waxes on onion foliage with the goal to develop cultivars resistant to onion thrips.