|Damon, Steve -|
Submitted to: National Allium Research Conference
Publication Type: Abstract Only
Publication Acceptance Date: September 22, 2012
Publication Date: November 29, 2012
Citation: Damon, S., Havey, M.J. 2012. Genetic variation for epicuticular waxes in onion: a thrips-avoidance mechanism [abstract]. National Allium Research Conference. Paper No. O-20. Technical Abstract: 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 plants can be classified as waxy, semi-glossy, and glossy indicating reduced amounts of epicuticular waxes. The goals of this research are to measure chemical differences in wax phenotypes using gas chromatography/mass spectrometry (GC-MS), 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 in order to dissolve the waxes and the chloroform solutions are then concentrated, derivatized, and analyzed using GC-MS. Variation in the quantities of several long-chain organic molecules was significantly associated with visual phenotypes with the most conspicuous difference being for hentriacontanone-16. A segregating family has been produced by crossing waxy by semi-glossy parents and is being used for chemical and genetic characterization of the epicuticular wax differences.