Grant Information
| Knowledge Area | Subject of Investigation | Field of Science | Percent |
|---|---|---|---|
| 201 - Plant Genome, Genetics, and Genetic Mechanisms | 999 - Citrus, general/other | 1080 - Genetics (excludes breeding) | 20% |
| 201 - Plant Genome, Genetics, and Genetic Mechanisms | 1430 - Greens and leafy vegetables (includes endive, lettuce, spinach, turnip-greens, celery, rhubarb, parsley, asparagus) | 1080 - Genetics (excludes breeding) | 15% |
| 205 - Plant Management Systems | 999 - Citrus, general/other | 1081 - Breeding | 15% |
| 202 - Plant Genetic Resources | 999 - Citrus, general/other | 1080 - Genetics (excludes breeding) | 10% |
| 203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants | 999 - Citrus, general/other | 1081 - Breeding | 10% |
| 204 - Plant Product Quality and Utility (Preharvest) | 1430 - Greens and leafy vegetables (includes endive, lettuce, spinach, turnip-greens, celery, rhubarb, parsley, asparagus) | 1081 - Breeding | 10% |
| 204 - Plant Product Quality and Utility (Preharvest) | 999 - Citrus, general/other | 1081 - Breeding | 10% |
| 206 - Basic Plant Biology | 999 - Citrus, general/other | 1081 - Breeding | 10% |
There are few public or private breeding programs for citrus or asparagus, but these are important crops in parts of the US and other countries. For the US industries that produce these crops to remain competitive, it is important that they produce fruits and vegetables that have the characteristics desired by consumers and that are also economic to produce. Public breeding and evaluation programs also provide growers with data on performance of varieties introduced from elsewhere that allows them to make more informed decisions about which varieties to grow. This project includes genetics and genomics research that makes breeding of these crops more efficient and effective, and uses this information to develop and release new varieties. In citrus the traits emphasized include fruit flavor, low seed content, productivity, tree size, disease resistance, and environmental stress tolerance. In asparagus the program focuses on producing varieties with high yield, good quality and disease resistance. Development of asparagus varieties that are more suited to mechanical harvesting is also an objective because the current practice of manual harvesting is difficult and costly. There is a shortage of trained plant breeders in the US and this program also trains graduate students for this career.
Outputs corresponding to each numbered objective are summarized below. 1) Results of genetic analyses will be made available through scientific publications and websites. 2) New scions and rootstocks will be released (some with patents) and disseminated to the citrus industry through commercial nurseries. Information on these new cultivars will be described in publications, on websites, and presented to growers at public meetings. 3) Results of genomic research will be made available through scientific publications and information will be deposited in public databases such as GenBank. 4) When new asparagus cultivars are released we will license seed producers to produce and sell commercial quantities of seed, and describe these cultivars at meetings and in publications. 5) Results from collaborative research will be made available through scientific publications.
To address objective 1 genetic control of various traits will be analyzed by producing hybrid populations in Riverside and measuring various traits on offspring. Data will be fit to models of Mendelian segregation or analyzed using QTL methods. We will use existing linkage maps supplemented with additional data from high-throughput SNP genotyping methods. An association mapping approach will be tested in mandarins where there may be an appropriate level of linkage disequilibrium. Mapping will be coupled to gene expression analysis using RNAseq to further localize candidate genes. For asparagus mapping the populations of interest were developed for single plant selection and have been scored for spear production and spear quality traits. Mapping will be integrated with ongoing genome sequencing efforts. New citrus scion and rootstock varieties will be developed by hybridization-selection and mutation breeding approaches, with initial evaluations conducted in Riverside and at the Lindcove Research and Extension Center near Visalia, CA. Replicated trials of scion selections will be conducted at 5-6 locations representing major production areas in California. Replicated trials of rootstocks will be conducted at field stations and with grower-cooperators. The origin and diversity of citrus germplasm will be assessed with high-throughput SNP genotyping methods and/or DNA sequencing. We will compare parent-mutant pairs to identify genes that affect traits of interest. A chemical genomics approach will be applied to tomato infected with psyllid yellows as a model system identify target genes that may control the closely related HLB disease of citrus. New asparagus cultivars will be developed by hybridization-selection approaches in Riverside and promising selections tested in replicated trials in Riverside and other asparagus production areas.
Target Audience
Target audiences for research are diverse and include other scientists working on breeding citrus, other fruit crops, and asparagus; extension personnel who conduct outreach on citrus and asparagus, growers who produce citrus and asparagus, and consumers.
Changes / Problems
The major change in emphasis was increased focus on HLB when this disease was first discovered in California and gradually spread in southern California. Various subprojects increasingly focused on this disease. A successful NIFA grant application resulted in development and application of high density SNP arrays for citrus. This focus was not originally anticipated.
Training & Professional Development
Three Ph.D. students were trained in molecular breeding and its application to citrus. Several visiting scientists also received training in citrus breeding, genetics, and genomics and presented posters at conferences. Two postdocs received additional training while contributing to research projects and attended conferences. Nine undergraduate students received training in lab, greenhouse, and field work of various kinds. Some conducted independent research projects and participated in conferences.
Dissemination Streams
Results have been presented to growers in several venues including talks and field presentations at UCR Citrus Day (once per year), the Lindcove Fruit Display in the San Joaquin Valley (once per year), talks organized by the California Citrus Research Board and UC Cooperative Extension Specialists and Advisors, Scientific audiences were reached during talks and posters at national and internation meetings, including the International Society of Citriculture, International Citrus Biotechnology Symposium, Plant and Animal Genome meeting, the International Society for Horticultural Science meeting, IV International Symposium on Molecular Markers in Horticulture meeting, and the Research Conference on Huanglongbing. Papers have been published in scientific journals reporting some of our accomplishments and others are still in preparation.
Next Reporting Steps
Nothing Reported