Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2004
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Citrus tristeza closterovirus (CTV) is the most economically important virus affecting citrus. Worldwide, it is estimated that more than 50 million trees have been lost to CTV with economic losses in the order of the hundreds of millions of US dollars. Different strains of the virus can cause diverse disease syndromes that vary from mild, with no visible symptoms; to quick decline and death of scions grafted on sour orange; to stem pitting and fruit size reduction of most species and varieties of citrus. Virions are long flexuous particles encompassed by two capsid proteins (CP), a major CP of 25 kDa (referred to in this work as CP) and a minor CP of 27 kDa (p27) that encapsidates about 5% of the terminal region of the particle. Including these two genes, the single-stranded, positive-sense genomic RNA encodes 12 open reading frames (ORFs). A long-term solution to the problems caused by CTV is the production of citrus varieties that are genetically resistant or immune to the virus. Here we discuss our ongoing effort of transforming grapefruit with CTV sequences and plant resistance genes in an effort to produce CTV-resistant citrus plants. Since the process of producing and growing transgenic citrus is labor-intensive and rather inefficient and CTV is a complex virus, our strategy has been to introduce individually a wide variety of CTV sequences to increase the chances of producing tolerant plants. The sequences include the CP gene from three different strains with distinct biological characteristics, a nontranslatable version of one of the CP genes, the RdRp, p27, and p20 genes and the 3'end (400 3'-terminal bases, including part of the p23 gene and the 3' UTR) of the CTV genomic RNA.