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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Publications at this Location » Publication #313953

Title: Epicuticular waxes and thrips resistance in onion

Author
item Havey, Michael
item DAMON, S - University Of Wisconsin
item DUANGJIT, J - University Of Wisconsin
item GROVES, R - University Of Wisconsin
item BOHANEC, B - University Of Ljubljana
item TOWN, C - J Craig Venter Institute

Submitted to: International Symposium on the Edible Alliaceae
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2015
Publication Date: 5/15/2015
Citation: Havey, M.J., Damon, S.J., Duangjit, J., Groves, R., Bohanec, B., Town, C.D. 2015. Epicuticular waxes and thrips resistance in onion [abstract]. International Symposium on the Edible Alliaceae. Paper No. O150127002.

Interpretive Summary:

Technical Abstract: Next-generation sequencing of normalized cDNAs from two inbred lines of onion revealed over 3000 well supported single nucleotide polymorphisms (SNPs), of which over 800 have been mapped. This SNP-based map was used to identify quantitative trait loci (QTL) controlling the amounts and types of epicuticular waxes on onion foliage. Wild-type onion possesses copious amounts of epicuticular waxes and is often referred to as “waxy”. The recessively inherited “glossy” phenotype has significantly less wax relative to waxy types. Phenotypes intermediate between waxy and glossy also exist in onion and are referred to as “semi-glossy”. Plants with lower amounts of epicuticular waxes suffer less damage by Thrips tabaci, a major insect pest of onion. Epicuticular waxes on the leaves of glossy, semi-glossy, and waxy onions were evaluated using Scanning Electron Microscopy and Gas Chromatography/Mass Spectrometry. The ketone hentriacontanone-16 is the most prevalent wax on leaves of waxy onion and largely responsible for the visual waxiness of foliage. Other major waxes included alkanes and fatty alcohols. Foliage of the glossy and semi-glossy phenotypes possessed significantly less of these waxes relative to waxy. Using a segregating family from the cross of waxy by semi-glossy plants, regions on chromosomes 2 and 5 controlled amounts of several primary fatty alcohols and hentriacontanone-16, respectively. These major QTL likely affect the decarbonylation and acyl-reduction pathways of epicuticular-wax biosynthesis. SNPs tagging these QTL should be useful for marker-assisted breeding to vary amounts and types of epicuticular waxes on onion foliage with the goal to develop thrips-resistant onions.