Update for this quarter:A substantial infrastructure renewal project is underway at the Picos location on USDA base funding. A full renovation of the water management system has been completed and will provide improved storm protection. Drainage channels were re-dug and cleared of vegetation. Culverts were inspected and replaced if damaged. The road surfaces have also improved to provide better vehicle access. Tree maintenance and field trials have received priority support under current conditions. Full assessments have been conducted on USDA transgenic plantings by onsite personnel. UF collaborators have been permitted into the test site; samples and data have been collected. A manuscript detailing results from the canker resistance assessment of replicated trifoliate and trifoliate hybrids planted in collaboration with NCGR-Citrus/Dates and UCRiverside was accepted for publication in Hortscience as Incidence of Asiatic Citrus Canker on Trifoliate Orange and its Hybrid Accessions in a Florida Field Planting. This site is also participating in a trial program to use drone based aerial photography for mapping and HLB assessment. The primary BRS permit, which covers the transgenic materials planted by Z. Mou, J. Jones, T. McNellis as well as USDA scientists has been renewed (AUTH – 0000043619 effective 1/27/2021). Recent quarters:An additional permit has been approved (AUTH – 0000043620 effective 12/17/2020) for material with “Confidential Business Information” for a project led by R. Shatters. Stover analyzed data on canker incidence for as Incidence of Asiatic Citrus Canker on Trifoliate Orange and its Hybrid Accessions in a Florida Field Planting. Most notably: Almost all accessions with lower ACC lesion incidence were hybrids vs. pure trifoliate, though a few pure Poncirus had lower ACC than most. Based on chloroplast genome data from 57K Affymetrix SNP chip, provided by M. Roose, 11 of 33 reported seed parentage for hybrids was inaccurate, convention of female first was not followed. Of 34 hybrids validated, similar numbers had Poncirus, grapefruit, and sweet orange chloroplasts. Chloroplast type did not affect ACC incidence, but in each year accessions with grapefruit chloroplasts had small but statistically higher ACC severity than those with Poncirus chloroplasts. Hybrids of Citrus with Poncirus have markedly reduced ACC sensitivity compared to Poncirus, indicating that this trait is readily overcome in breeding. A manuscript has been prepared and submitted from this data. Previously established at the site:A number of trials are underway at the Picos Test Site funded through the CRDF. A detailed current status is outlined below this paragraph. Continuation of an experiment on pollen flow from transgenic trees. FF-5-51-2 trees are slightly more than 1000 ft from the US-802, and are self-incompatible and mono-embryonic. If pollen from transgenic trees is not detected from open-pollination, it should reduce isolation distances required by BRS. Early-flowering transgenic Carrizo (flowered ex-vitro within five months of seed sowing, and used at 12 months) was used to pollinate some of the same FF-5-51-2 What should be the final samples from the C. Ramadugu-led Poncirus trial (#3 below) completed preparation and were shipped in ethanol to UC Riverside. Availability of the test site for planting continues to be announced to researchers. Plantings:1) The UF Grosser, Dutt and Gmitter transgenic effort has a substantial planting of diverse transgenics. These are on an independent permit, while all other transgenics on the site are under the USDA permits.2) Under the Stover permit, a replicated planting of 32 transgenic trees and controls produced by Dr. Jeff Jones at UF were planted. These trees include two very different constructs, each quite specific in attacking the citrus canker pathogen. 3) A broad cross-section of Poncirus derived material is being tested by USDA-ARS-Riverside and UCRiverside, and led by Chandrika Ramadugu. These are seedlings of 82 seed source trees from the Riverside genebank and include pure trifoliate accessions, hybrids of Poncirus with diverse parents, and more advanced accessions with Poncirus in the pedigree. Plants are replicated and each accession includes both graft-inoculated trees and trees uninfected at planting. 4) More than 100 citranges, from a well-characterized mapping population, and other trifoliate hybrids (+ sweet orange standards) were planted in a replicated trial in collaboration with Fred Gmitter of UF and Mikeal Roose of UCRiverside. Plants were monitored for CLas titer 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. Manuscripts have been published reporting HLB tolerance associated QTLs and differences in ACP colonization. Trees continue to be useful for documenting tolerance in a new NIFA project.5) A replicated Fairchild x Fortune mapping population was planted at the Picos Test Site in an effort led by Mike Roose to identify loci/genes associated with tolerance. This planting also includes a number of related hybrids (including our easy peeling remarkably HLB-tolerant 5-51-2) and released cultivars. Genotyping, HLB phenotyping and growth data have been collected and will continue to be conducted under a new NIFA grant.6) Valencia on UF Grosser tertazyg rootstocks have been at the Picos Test Site for several years, having been CLas-inoculated before planting, and several continue to show excellent growth compared to standard controls (Grosser, personal comm.).7) In a project led by Fred Gmitter, there is a planting of 1132 hybrids of C. reticulata x C. latipes. C. latipes is among the few members of genus Citrus reported to have HLB resistance, and it is expected that there will be segregation for such resistance. The resulting plants may be used in further breeding and may permit mapping for resistance genes. 8) Seedlings with a range of pedigree contributions from Microcitrus are planted in a replicated trial, in a collaboration between Malcolm Smith (Queensland Dept. of Agriculture and Fisheries) and Ed Stover. Microcitrus is reported to have HLB resistance, and it is expected that there will be segregation for such resistance. The resulting plants may be used in further breeding and may permit mapping for resistance genes. 9) Conventional scions on Mthionin-producing transgenic Carrizo are planted from the Stover team and are displaying superior growth to trees on control Carrizo.10) Planting of USDA Mthionin transgenics with 108 transgenic Hamlin grafted on wild type Carrizo (7 events represented), 81 wild type Hamlin grafted on transgenic Carrizo (16 events represented) and 16 non-transgenic controls. 11) Grafted trees of conventional sweet orange and grapefruit scions on transgenic rootstock expressing antimicrobial citrus-thionin and bacterial recognition domain fusion proteins (165 trees with controls) as a collaboration between USDA and Innate Immunity.12) Planting was made of transgenics from Zhonglin Mou of UF under Stover permit, with 19 trees of Duncan, each expressing one of four resistance genes from Arabidopsis, and 30 Hamlin expressing one of the genes, along with ten non-transgenic controls of each scion type. 13) Transgenic trees expressing FT-ScFv (12 transgenic and 12 control) to target CLas from Tim McNellis of Penn State14)Numerous promising transgenics identified by the Stover lab in the last two years have been propagated and will be planted in the test site.