Current and Recent Research Activities That Utilize the Givaudan Citrus Variety Collection

The Givaudan Citrus Variety Collection (GCVC) is a resource for research and outreach activities as it has been since the collection was first established in 1910. Today, as our knowledge of citrus is expanding, so too have the ways in which the GCVC is used to enhance this understanding.

Below are descriptions of recent and current research projects that utilize and explore the genetic and observable and aromatic diversity of the different cultivars and species in the genus Citrus and closely related genera:

"We utilize plants in the GCVC for conducting breeding.  Our goal is to introgress Huanglongbing resistance traits into cultivated citrus. Towards this objective, we have conducted crosses utilizing a number of citrus accessions as breeding parents." - Chandrika Ramadugu, University of California, Riverside, Department of Botany and Plant Sciences

"As part of our funding from the Citrus Research Board each year, we evaluate fruit quality traits of selected newly introduced cultivars three to four times per season to determine their timing of maturity and assess whether they should be considered for future field trials to determine commercial potential." -Toni Siebert Wooldridge, Karene Trunnelle and Tracy Kahn, University of California, Riverside, Department of Botany and Plant Sciences

"We utilize the GCVC to explore phenotypic diversity across citrus. Our current focus is on traits related to tree performance and fruit characteristics. Ultimately, we plan to dissect the genetic control of each trait to facilitate the development of new citrus varieties with desirable characteristics." - Danelle Seymour, University of California, Riverside, Department of Botany and Plant Sciences

"For our grant funded by USDA FACT, we are collecting leaf metabolomic profiles of 250 selected GCVC accessions to pair these data with existing genomic data generated by the Roose laboratory and phenotypic data from the Seymour laboratory for a multi-omics data analysis. The knowledge acquired from this advanced analysis will help us better understand the genetic determinants of important traits, which will assist in genomic selection or genomic breeding in citrus." - John Chater and Zhenyu Jia, University of California, Riverside, Department of Botany and Plant Sciences

"For our Leaf Shape Study funded by USDA FACT, we are analyzing the leaf shape profiles of 250 GCVC accessions to identify the genes that determine leaf shape morphology variables associated with agronomically important traits. The success of this project will not only advance our knowledge of the biology behind leaf shape traits, fruit traits, and their associations, but also help develop novel selection strategies for citrus breeding." - Ryan Trabad, John Chater and Arthur Jia, University of California, Riverside, Department of Botany and Plant Sciences 

"A team of Givaudan scientists are collaborating with UCR Chemists to investigate the variation in the aromatic leaf oils from the citrus collection. The chemical profiles were compared with other published data in the search for new flavour ingredients from citrus." - Robin Clery, Flavour Science and Technology, Taste & Well-Being, Givaudan.

"We study diversity and phylogeny of citrus in the collection using an Affymetrix SNP array that has been used to genotype more than 50,000 positions in the citrus genome of every accession. This improves our understanding of the diversity that exists in the collection and of citrus evolution, and identifies gaps in the collection.  This data is also useful to infer parentage of many accessions, and local ancestry analysis determines the species that contributed each chromosome segment to each accession, information that assists breeders in developing new cultivars." - Yoko Hiraoka and Mikeal Roose, University of California Riverside, Department of Botany and Plant Sciences.

"We are determining the percent zygotic seedlings produced by many accessions with nucellar embryony by testing large samples of seedlings with LGC KASP SNP markers.  These results are then related to Affymetrix SNP array data on the seed parent to identify genetic factors that influence the percent zygotic seedlings." - Yoko Hiraoka and Mikeal Roose, University of California Riverside, Department of Botany and Plant Sciences.

"We have developed a method to determine the genotype or DNA sequence of single citrus pollen grains which have only two copies of the genome, and from this approach we have determined the haplotype (which DNA of each chromosome originated from mother vs father) of 48 important accessions. This information should facilitate more efficient citrus breeding." - Sergio Ferrante and Mikeal Roose, University of California Riverside, Department of Botany and Plant Sciences.

"Utilizing seed collected from Microcitrus and Eremocitrus cultivars in the GCVC along with a hybrid from the breeding collection, the Roose lab is testing the effects these relatives have on Navel fruit quality and yield when utilized as rootstocks. Relatives are a source for resistance to HLB and if they are to be used as parents for future rootstocks it is important to know how they will affect the fruit we grow and eat." - Zach Thomas and Mikeal Roose, University of California Riverside, Department of Botany and Plant Sciences.

"The UCR Citrus Breeding Program uses many accessions in the GCVC as parents to produce new hybrid cultivars with better fruit quality, more efficient and sustainable production. - Toni Siebert Wooldridge, Karene Trunnelle, Claire Federici, and Mikeal Roose, University of California, Riverside, Department of Botany and Plant Sciences

"The Roper lab is currently studying microbes isolated from trees in the Citrus Variety Collection that may help cure or prevent the deadly disease Huanglongbing." - Christopher Dozd and Caroline Roper

"We collected the leaves of various citrus varieties and citrus-relatives from GCVC to extract RNA for comparative gene expression analysis in different genetic background. We identified different homologous and orthologous genes of stable anti-microbial peptide (SAMP), originally isolated from Australian finger lime.  We discovered that SAMP from finger limes and citrus close relatives can inhibit infection and growth of CLas, the bacterium causes citrus Huanglongbing, the most  devastating citrus disease that threatens the entire citrus industry globally.  This peptide can also induce plant immune responses and can be potentially used as vaccines to protect the citrus plants from future infection. We are now actively working together with our Industry Partner to conduct field trials with SAMP application. Ultimately, we hope to develop therapeutic and preventive solutions to control citrus Huanglongbing." - Hailing Jin and Chien-Yu Huang