B&GPast – Page 2

2007 Mikeal Roose (Genetic Maps of Sweet Orange)

Genetic Maps of Sweet
Orange and Trifoliate Orange

This project continued development of genetic maps of sweet orange and trifoliate orange, two very important scion and rootstock cultivars and breeding parents. Patterns of genetic transmission of various DNA markers were studied in a large population of hybrids from crosses of sweet orange with trifoliate orange. These data will be used to construct genetic maps that show the order of markers along citrus chromosomes and indicate the frequency with which various markers are transmitted jointly to offspring.

2007 Kentaro Inoe (Molecular Analysis of Greening)

Molecular Analysis of Degreening and Regreening in Valencia Orange

Orange fruits change their peel color from green to orange during maturation and ripening. This color development (“de-greening”) is an important factor to determine the commercial quality of fruits. On one hand, the green fruits accumulate not only green pigments (chlorophylls) but also orange/yellow pigments (photosynthetic carotenoids) which are hidden under chlorophylls. On the other hand, the orange fruits lack chlorophylls and accumulate carotenoids which are different in their structure from those found in the green fruits.

2007 Hailing Jin (Small RNA for HLB Plant Response)

Identification of Candidatus Liberibacter-induced Small RNAs for Early Diagnosis of HLB Citrus Greening

Citrus greening or “Huanglongbing” (HLB), caused by bacteria Candidatus Liberibacter, is one of the most destructive diseases of citrus. Recent confirmation of HLB in Florida is of great concern to the citrus industry. To prevent its further spread, early diagnosis before the appearance of the dreaded symptoms is particularly important. However, the unculturable nature of the bacteria and their low concentration and uneven distribution in the hosts make it extremely difficult to detect HLB infection.

2007 Georgios Vidalakis (Small RNA for Stubborn Response)

Identification of Spiroplasma citri-induced Small RNAs for Early Diagnosis of Citrus Stubborn Disease

In California, the Stubborn disease is responsible for losses in the fruit yield and quality. In addition, as an insect-borne pathogen Spiroplasma citri is a constant threat for the Citrus Clonal Protection Program (CCPP), the most important source of citrus propagative material for the state of California. The available laboratory diagnostic protocols are targeting the pathogen S. citri, and many times their results are unreliable because of the low titer and the erratic distribution of the pathogen in the citrus.

2007 Eduardo Blumwald (Determinants of Sugar and Acid)

The Determinants of Sugar and Acid Content in Citrus Fruits and Citrus Fruit Proteomics

The general objective of our work is the characterization of the physiological, biochemical and molecular components that control the accumulation of TSS (Total Soluble Sugars) and TA (Total Acidity) in citrus fruits. The understanding of the cellular/molecular determinants for TSS and TA content in fruits will allow the enhancement of fruit quality during pre- and post-harvest practices, the improvement of citrus fruit acidity and sweetness, and the characterization of fruit disorders that depend on TSS and TA fruit content.

2007 Abhaya Dandekar (Improving Peel Quality in Citrus)

Improving PeelQuality of California Citrus Fruit

An essential component of high quality citrus fruit is an external finish free of blemishes, defects, and disease. The peel or rind of citrus fruit, composed of flavedo and albedo layers, is a highly physiologically active tissue prone to injury and environmental influence. Our study is establishing relationships between internal fruit quality, specific disorders, and expression of specific genes.

2007 Henry Fisk (Genetic Engineering of Citrus)

Genetic Engineering of Citrus

The primary goal of this project has been to develop genetic transformation methods for citrus rootstock and scion cultivars important to the California industry. Establishment of this technology would represent a significant advancement towards efforts to better understand and improve these species using methods based in conventional breeding, biotechnology or a combination of the two. Alternatively, these methods may be used as experimental tools to help scientists learn more about citrus biology which, in turn, may lead to better information regarding more productive horticultural practices with traditional trees.

2007 Abhaya Dandekar (Seedlessness Strategies for Citrus)

Evaluating and Validating
Seedlessness Strategies for Citrus

The presence of seeds in fruit is an undesirable feature for most consumers because of their hard or leathery texture, their bitter taste, and sometimes the presence of toxic compounds and allergens that can be harmful. Replacing seeds and seed cavities with edible fruit tissue is attractive to consumers, especially in species like citrus with many seeds per fruit.