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Plant Improvement – Page 2

2005 Fisk/Dandekar (Genetic engineering of Citrus)

Genetic Engineering of Citrus

The main goal of this work has been to develop genetic transformation methods for citrus scion cultivars important to the California industry. The cultivars investigated during the 2004-05 funding cycle included Washington navel and Valencia sweet oranges, Kinnow and Owari Satsuma mandarins, Eureka lemon and Mexican lime. Additional varieties, particularly mandarins, have been considered for future experiments.

2005 Wright/Kahn/Mauk (Evaluation of Lemon Selections for the Desert)

Evaluation of Lemon Selections for the Desert

For more than 75 years, California has been a leader in the worldwide fresh lemon industry. To maintain and increase its market share, steps that the industry must take include developing high quality lemon varieties that are adaptable to the diverse California climates, meet the demands of the marketplace, and produce acceptable returns for the grower.

2005 Mary Lu Arpaia (Harvest and Evaluation of Strain Trials at Lindcove)

Harvest and Evaluation of Strain Trials at Lindcove Research and Extension Center

Our progress on the two portions of this study is outlined below, plus a near-final summary of the Valencia strain portion of the project which was terminated in 2003.

2005 Mikeal L. Roose (Breeding of New Citrus Scion Varieties)

Breeding of New Citrus Scion Varieties

The objectives of this project are to develop new mandarin, orange, lemon and grapefruit cultivars suitable for California conditions. Developing new varieties is a long-term project that has been funded by the CRB since 1994.

2005 Tracy L. Kahn (Citrus Variety Evaluation for Trueness-To-Type)

Citrus Variety Evaluation for Trueness-to-Type and Commercial Potential

High quality citrus varieties which are adapted to California climates and meet market needs are crucial to the industry to maintain competitiveness in the global and domestic fresh citrus markets. To be responsive to market changes such as the increasing market desire for seedless tangerines, our project continues to provide the industry with preliminary information on the characteristics of citrus varieties in California, to evaluate trueness-to-type of varieties distributed by the Citrus Clonal Protection Program, and to maintain the citrus evaluation blocks to serve as demonstration material for tours, fruit displays and periodic field days for California growers.

2005 Mikeal L. Roose ( Citrus Rootstock Breeding and Evaluation)

Citrus Rootstock Breeding and Evaluation

The general objectives of this project are to develop, test and evaluate citrus rootstocks for disease and pest tolerance, and to select stocks which impart to the scion high yield, superior fruit quality, acceptable fruit size, and other essential traits. This is a long-term project that has been supported by the CRB since 1982.

2006 M. L. Arpaia (Harvest and Evaluation of Strain Trials at Lindcove Research and Extension Center)

Harvest and Evaluation of Strain
Trials at Lindcove Research and Extension Center

Navel Strain Trial: We had several early season samplings to examine the differences between the strains with respect to rind color, SSC, TA and SSC/TA. The early strains were har-vested in December 2005 from all replicates, the mid-season strains were harvested in March 2006 and the late season strains were harvested in May 2006. All fruit were run over the packline at UC Lindcove REC for size and grade. We col-lected fruit quality data for each strain at the time of harvest. All data from this season has been entered and is currently being analyzed with the exception of the packline data.

2006 Eduardo Blumwald (Physiological and Biochemical Determinants of Sugar and Acid Content in Citrus Fruits and Citrus Fruit Proteomics)

Physiological and Biochemical
Determinants of Sugar and Acid Content in Citrus Fruits and Citrus Fruit Proteomics

The sugar content and acidity of the juice cells are key deter-minants of citrus fruit quality. Both juice cell citric acid and sugar content change during development and determine to a great extent the TSS (Total Soluble Solids) /TA (Total Acidity) ratio of the fruit. The TSS/TA ratio of the fruit will determine whether the fruit can be marketed.

2006 Timothy J. Close (EST Libraries and Bioinformatics for California Citrus)

EST Libraries and Bioinformatics for California Citrus

This project produces fundamental resources and information in the area of “Genomics” that facilitate other research and practical applications. The information is about the genes, proteins and metabolic pathways of citrus. Research appli-cations include identification of genes that underlay retention of flavor during fruit storage, predisposition of sour orange to quick decline, and development of transgenic strategies to investigate gene-trait relationships and develop new varieties.

2006 Abhaya M. Dandekar (Evaluating and Validating Seedlessness Strategies for Citrus)

Evaluating and Validating Seedlessness Strategies for Citrus

Elimination of seed formation in citrus cultivars such as lemon and Mandarin orange would be of great value to the citrus industry and consumers. Several genetic strategies reduce or eliminate seeds in fruit: we are evaluating the ability of ovule-specific auxin regulation to induce parthenocarpy. Patheno-carpy is fruit formation in the absence of fertilization. It occurs naturally in some plants and results in seedless fruits. We are testing this strategy in tomato and then citrus by manipulating auxin synthesis or responsiveness in ovules of these plants with tissue-specific promoters.