Location: Vegetable Crops Research Unit
Title: Genetic variation for epicuticular waxes in onion: a thrips-avoidance mechanism Authors
|Damon, Steve -|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 30, 2012
Publication Date: August 8, 2012
Citation: Damon, S., Havey, M.J. 2012. Genetic variation for epicuticular waxes in onion: a thrips-avoidance mechanism [abstract]. National Association of Plant Breeders 2nd Annual Meeting. p. 21. Technical Abstract: Onion (Allium cepa) is the second most valuable vegetable crop in the world and the third most valuable in the USA. Thrips are one of the main insect pests of onion, causing damage to leaves and stored bulbs as well as transmitting serious diseases such as Iris Yellow Spot Virus and bacterial bulb rots. Reduced quantity and possibly altered chemistry of epicuticular waxes contribute to thrips tolerance in onion. Natural variation exists for epicuticular waxes in onion and has been classified as waxy, semi-glossy, and glossy. The goals of this research are to measure chemical differences in wax phenotypes using gas chromatography/mass spectrometry (GCMS), and to determine the genetic bases of these differences. Independent sources of glossy, semi-glossy, and waxy onions from the USDA germplasm collection and breeding program were evaluated. Leaf samples were dipped in chloroform for one minute in order to dissolve the waxes. The chloroform solutions were concentrated, derivatized, and analyzed using GCMS. Variation in the quantities of several long-chain organic molecules was significantly associated to the phenotypes with the most conspicuous being hentriacontanone-16. A segregating family has been produced by crossing waxy by semi-glossy parents and will be used for chemical and genetic characterization of the epicuticular waxes.