Variation for epicuticular waxes and thrips resistance in onion

Authors: DAMON, STEVEN - University Of Wisconsin; GROVES, RUSSELL - University Of Wisconsin; Havey, Michael

Submitted to: Plant Breeding Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/30/2015
Publication Date: 8/27/2015
Citation: Damon, S., Groves, R., Havey, M.J. 2015. Variation for epicuticular waxes and thrips resistance in onion [abstract]. Plant Breeding Conference Proceedings. p. 26.

Interpretive Summary:

Technical Abstract: Onion thrips (Thrips tabaci) and thrips-vectored Iris Yellow Spot Virus (IYSV) routinely cause significant losses to the bulb and seed crops of onion. Both pests have become more problematic as global temperatures rise. Natural variation exists in onion for amounts and types of epicuticular waxes on foliage, and plants with lower amounts of these waxes have been observed in the field to suffer less damage from thrips and IYSV. Epicuticular waxes on the leaves of onion accessions were evaluated for appearance using SEM and amounts and types determined using GC/MS. Specific ketones and fatty alcohols are the most prevalent waxes on leaves of onion and accessions were identified with significantly (P<0.01) less of these waxes. In field and greenhouse experiments, numbers of adult and immature thrips were significantly reduced (P<0.05) on accessions with less total wax relative to wild-type onions. Genetic mapping revealed that amounts of the primary ketone are controlled by a region on chromosome 5 and fatty alcohols on chromosome 2, indicating that onions can be developed with different compositions and amounts of epicuticular waxes. Intermediate amounts of epicuticular waxes should protect leaves from diseases and environmental stresses, while suffering less damage from thrips and IYSV, in an integrated program to manage these important onion pests.