1) Trees have been in the ground for 4 years in a trial of 50 selections and cultivars on US-802 following no-choice ACP inoculation and several months in an ACP house. Standard growth measurements and disease ratings were initiated in July 2014 and will continue on a semi-annual basis. HLB is now widespread and the trees looking healthiest include a full sib of our best mandarin selection (unfortunately not in this trial). Several of our best grapefruit-like hybrids looked good last year but are now declining. The one true grapefruit is the least healthy selection in the trial. The best performers include hybrids containing Poncirus, and conventional hybrids which are predominately mandarin. It may take 2-3 more years to clearly distinguish tolerant material. These trees are cropping this year, and fruit will be used in a complementary project exploring synthesis of orange-like juice from HLB-tolerant types. The 5 selections with the highest percent of full canopy volume ratings had 46% to 57% increase in canopy volume over the last year while the 7 with the lowest percent of full canopy volume ranged from 0 to 23% increase. Several selections that had looked good last year suddenly dropped to a very low canopy increase, and it appears this may be a relatively early indicator of HLB tolerance. 2) In June 2015 a field planting was established of: seedling trees of 133 Fortune x Fairchild hybrids from an earlier mapping study, seedlings of 27 Ponkan-like accessions, budded trees of 10 advanced ARS selections that are predominately mandarin, and budded trees of Fortune, Fairchild and Valencia. Data collection is underway. A genotyping project was initiated with 688 seedlings trees of Fortune x Fairchild and 235 Ponkan type seedlings. This samples will be collected at picos farm and determined with zygosity KASP markers designed by Roose group at UCR. Monoembryonic hybids will be identified and used for HLB-tolerance mapping analysis as part of a new NIFA grant. 3) Replicated trials in multiple locations are established of our best sweet-orange-like cultivars and mandarin-types. Volatiles from sweet-orange-like hybrids are so similar to sweet orange that likely can be legally named sweet orange. 4) RNA-seq compared transcriptome responses in HLB moderately tolerant �Sun Chu Sha� mandarin and susceptible �Duncan� grapefruit, to Xcc-flg22 and CLas-flg22 (most active epitope from the pathogen flagella; project initiated with Gloria Moore at University of Florida). Differential expression of a number of genes occurred between tolerant and susceptible citrus infected with CLas, suggesting their involvement in HLB tolerance. In addition, several genes were similarly regulated by CLas-flg22 and CLas treatments. Genes identified were recently published and are valuable for studying HLB tolerance mechanisms and potential for screening for HLB-tolerant citrus using CLas-flg22 as a pathogen proxy. A population of mandarin hybrids from a 2015 cross was used to test for CLas-flg22 responsiveness. Leaf injections of CLas-flg22 and Xcc-flg22 were conduct on about 60 seedlings, and 8 randomly selected plants were subject to expression analysis of marker genes identified by transcriptomics previously. CLas-flg22 injection induced marker genes in several plants, although the number of markers induced was inconsistent. The analysis of the remaining 50 plus plants is underway. 5) A group of CLas effector (28) was predicted using bioinformatics tools. The study of transcriptional level of these effectors in infected citrus samples was initiated. Many of the effectors were successfully detected by RT-qPCR in citrus RNA, suggesting their roles in pathogen virulence and host response modulation. The number of effectors detected has a positive linear relationship with bacterial titer, but less association with infection stage within the first week of CLas inoculation. The effectors� expression were compared in citrus hosts with various levels of HLB tolerance, including citron, Duncan grapefruit, Cleopatra mandarin, Pomeroy trifoliate, Carrizo citrange and Washington navel orange, and indicated relatively high expression of CLIBASIA_03695, CLIBASIA_00460, CLIBASIA_00420, CLIBASIA_04580, CLIBASIA_05320, CLIBASIA_04425, CLIBASIA_00525 and CLIBASIA_05315 in either a host-specific or -nonspecific manners. In another study, the expression of effectors was compared between leaves and roots of citrus that has been Ca. L. asiaticus-infected for more than a year. Results indicated relative high expression of CLIBASIA_03875, CLIBASIA_04800 and CLIBASIA_05640 in all leaf and certain root tissues of citron, Duncan and Cleopatra. Some of the highly expressed effector candidates will be further tested for the correlation with host tolerance/susceptibility, and the potential used as biomarkers for resistance screening of breeding materials. 6) Seedlings with a range of pedigree contributions from Microcitrus have been received in a collaboration with M. Smith, Queensland Aus. citrus breeder, are being grown, and will be planted next quarter for field testing of HLB resistance. 7) Our putative chimeras have not proven to be successful. We identified a chimera (Satsuma and Poncirus) from the Citrus genebank, arranged its importation, and we finally got permission to accept this material and maintain it in a quarantine death house. Cuttings of the chimera and each separate component (Owari and Poncirus) were rooted and were challenged by hot ACP feeding and data will be collected in the next quarters.