Author
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Stover, Eddie |
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Submitted to: River Ramblings: the newsletter of the Indian River Citrus League
Publication Type: Other Publication Acceptance Date: 10/28/2014 Publication Date: 11/15/2015 Citation: Stover, E.W. 2015. Update on USDA advanced citrus scion selections for Indian River Citrus League. River Ramblings: the newsletter of the Indian River Citrus League. p 1. Interpretive Summary: Technical Abstract: In its 120 year history, the USDA citrus scion breeding program has provided the mainstays of the Florida specialty citrus industry. In the last few years, the USDA has released US Early Pride mandarin, US Seedless Pineapple sweet orange and most recently, US Furr/US Furr-ST mandarin. Clearly huanglongbing (HLB) is the 800 pound gorilla in the citrus world and it is a major focus of our program. Host resistance or tolerance to HLB offers the promise of a sustainable long-term solution to maintain economic citrus production. All citrus cultivars are not equal in their susceptibility to HLB. Sweet orange cultivars are about as similar to each other genetically as are identical twins, and grapefruit is an offspring of sweet orange. This narrow genetic base makes us especially vulnerable to a disease epidemic, such as we are seeing with HLB. We are identifying HLB tolerant/resistant selections and through breeding are attempting to pyramid sources of HLB tolerance/resistance into diverse market types. There is especially strong evidence of HLB tolerance in some selections with “near-commercial-fruit quality” that have some trifoliate orange in their pedigree. Even more excitingly, initial observations suggest that some very sweet-orange like selections are less susceptible to HLB than sweet oranges. USDA selections are aggressively challenged with HLB to identify those that look promising. Transgenics appear to be the most promising solution for strong HLB resistance and perhaps immunity. Another major advantage is the ability to improve an existing cultivar through transgenics with essentially no other changes: HLB-resistant Valencia, Ray Ruby, Navel, Tango etc. Clearly we have a lot invested into maintaining cultivars that our processors and packers know and understand, and that our customers know and want. The USDA is using transgenics as just another source of variability in breeding and we are reaching out broadly to collaborate with other researchers to bring diverse, high-potential tools to direct against HLB. The citrus research community understands the urgency of finding HLB solutions, and a great deal of good work is underway. It seems likely that we will see an evolution in solutions over time, first combining therapies and strategies to maintain production on established trees, perhaps transitioning to less susceptible citrus types as replanting occurs, and ultimately planting trees that are fully immune to HLB. The folks in the USDA citrus breeding program are committed to helping develop such solutions. |
