2011 Annual Report 1a.Objectives (from AD-416) Provide expertise in the area of genetic analysis of germplasm of citrus, citrus relatives, and date palm. This supports the mission to collect, evaluate, and distribute germplasm of citrus, citrus relatives, and date palm. 1b.Approach (from AD-416) Use molecular markers and gene sequence information to characterize citrus, citrus relatives, and date palm accessions to help identify redundancies and gaps in the collection, screen potential new accessions, and identify important regulatory genes of metabolic pathways. 3.Progress Report Nuclear gene sequence-based phylogeny of Citrus: Many plants belonging to Rutaceae subfamily Aurantioideae are significant for citriculture. Citrus relatives play an important role in breeding, as root stocks and as alternate hosts for major diseases like Huanglongbing or citrus greening. We are interested in studying members of Aurantioideae and determine their role in spreading HLB, in serving as alternate hosts for the associated pathogen and in identification of possible tolerant/resistant species. Proper identification of the citrus relative is extremely important since a lot of confusion exists in literature regarding the nomenclature. We have developed a molecular method to bar-code citrus relatives based on the sequence of a house-keeping gene, malate dehydrogenase. In our project we have developed sequence information for 29 genera of Aurantioideae and identified single nucleotide polymorphisms in a 1600 bp sequence. We have used this information to study phylogeny, to aid in proper identification of the plants and also in identification of the potential disease resistant cultivars. This research is related to objective 3 of the parent project. The project was monitored by meetings, site visits, e-mail correspondence, and phone calls.