Creation, Development, and Screening of Citrus Germplasm for Resistance to HLB and Citrus Canker (Core Breeding)

Creation, Development, and Screening of Citrus Germplasm for Resistance to HLB and Citrus Canker (Core Breeding)

Report Date: 03/20/2016
Project: 539   Year: 2015
Category: Plant Improvement
Author: Fred Gmitter
Sponsor: Citrus Research and Development Foundation

Three Valencia-type clones (N7-11, B7R9T35 and B7R9T36) with excellent fruit quality were discovered in our collection (older trees) that have no HLB symptoms and are PCR-negative for Liberibacter. Trees of these clones have been propagated for further study. Juice quality, as assessed by a large citrus juice company in Florida, was found to be excellent. We continued to monitor performance, assess HLB severity, tree growth and yields of late maturing sweet oranges at different field sites throughout Florida. Also, we received seeds from collaborators in Sicily of rootstock candidates that showed good preliminary performance at St. Helena, as well as some new candidates of identical parentage for future trials. Seeds were planted to produce larger numbers of trees for extended trials. Gauntlet rootstock screening: Approximaly 75 HLB+ Valencia budstick-grafted hybrid rootstocks already passed through the ‘hot psyllid’ house were planted at Picos Farm in Ft. Pierce. Three parental combinations from 2013 crosses produced numerous hybrids that are growing off beautiful trees from grafted HLB+ Valencia budsticks: C2-5-12 pummelo x C. latipes (papeda); Amblycarpa+HBPummelo x Sour orange+rangpur; and Amblycarpa+HBPummelo x White #1. Stick-grafting and production of rooted cuttings from 2013 gauntlet crosses has been completed. The two early-maturing (December) Valencia somaclones identified, B7-70 and SF14W-65, have been cleaned up and a few pathogen-free trees were provided by the Parent Tree Program (DPI). We are following our plans for rapid pathogen-free budwood increase. We are moving quickly to have a substantial population of budwood increase trees available for nurseries at the time of the official release announcement. These clones have been put up for official release approval this summer, 2015.


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