2012 Annual Report
A transgenic test site has been prepared at the U. S. Horticultural Research Lab's Picos Farm in Ft. Pierce, to support HLB/Asian Citrus Psyllid (ACP)/CBC resistance screening for the citrus research community. There are numerous experiments in place at this site where HLB, ACP, and citrus canker are widespread. The first trees have been in place for more than two years.
University of Florida (UF) has provided 550 transgenic citrus plants expressing genes expected to provide HLB/CBC resistance, which have been planted in the test site. University of Florida planted an additional 89 trees including preinoculated trees of sweet orange on a complex tetraploid rootstock that appeared to confer HLB resistance in an earlier test. U.S. Horticultural Research Lab has a permit approved from Animal Plant and Health Inspection Service (APHIS) to conduct field trials of their transgenic plants at this site, with several hundred transgenic rootstocks in place: ARS scientist has planted several hundred rootstock genotypes transformed with the antimicrobial peptide D4E1. A material transfer agreement is in place to permit planting of Texas A&M defensin transgenics and Texas A&M trees expressing the snow-drop Lectin (to suppress Asian Citrus Psyllid) are now on the ARS permit. More than 100 transgenic trees from ARS and Texas A&M have been planted for assessment of effects of lectins on ACP. Information has been provided to complete the permit application by Texas A&M to plant transgenics which have altered Ca metabolism to target CBC, HLB and other diseases.
More than 120 citranges, from a well-characterized mapping population, and other trifoliate hybrids (+ sweet orange standards) have been planted in a replicated trial in collaboration with University of Florida and University of California/Riverside. Plants will be monitored for Liberibacter development and HLB symptoms. Data from this trial should provide information on markers and perhaps genes associated with HLB resistance, for use in transgenic and conventional breeding.
Additional plantings are welcome from the research community. This project has been renewed by Citrus Research Development Foundation for an additional three years.