摘要：柑桔破葉病(tatter leaf)與萎縮病、黃龍病並稱是亞洲最嚴重的三大柑桔系統性病害。該病是由柑桔破葉病毒（Citrus tatter leaf virus = CTLV）所引起，分類上隸屬於Capillovirus屬，基因體為(+)ssRNA，長度650nm。此病毒引起枳橙類柑桔產生破葉病徵，並在許多柑桔品種上造成砧木與接穗不親和的裂痕，影響植株發育且易受強風摧折。全世界對此重要病害的研究尚屬不多，申請人多年來一直致力於柑桔病毒與類病毒病害之研究，已累積不少學術成果。CTLV是我國柑桔防疫的重點，在今年農委會公告實施的「柑桔無指定疫病蟲害種苗驗證作業須知」中，CTLV是四大檢疫要項之ㄧ。本研究計畫之施行將有助於柑桔健康種苗制度之推行與整體柑桔防疫政策之達成。此計畫擬從生物性與分子性兩方面探討並鑑定不同的CTLV系統，並且同時研發各種快速偵測法，包括RT-PCR、單元抗體、Real-time RT-PCR等相關偵測技術，以供防疫檢疫之應用。因為CTLV在柑桔寄主體內濃度低，純化十分耗時；再者，其病毒系統可能相當複雜，加上柑桔品種多，植株生長緩慢，故柑桔病毒的生物性或生態性試驗常需較
Abstract: Citrus tatter leaf, tristeza and huanglongbing are the most important systemic diseases of citrus. Citrus tatter leaf virus (CTLV), the pathogen causing tatter leaf, is categorized into the genus Capillovirus consisting of a single-stranded positive-sense RNA genome packaged in 650nm flexuous particles. CTLV induced the “tatter leaf” symptom in citrange hosts and “bud-scion crease” in many other citrus cultivars, which retarded citrus growth and sometimes broke at the bud union when strong wind blew. CTLV is a main subject in the policy of integrated pest control of citrus in Taiwan. This research project is dedicated to categorize the different CTLV strains from the biological and molecular level, also develop rapid detection techniques for CTLV with several methods such as RT-PCR, monoclonal antibodies and Real-time RT-PCR. Strain-categorization studies are helpful for understanding the variations and pathogenicities of CTLV in different citrus cultivars from various cultivated areas. Designing an experiment for citrus diseases requires long-term data gathering to obtain objective biological data. Thus, a three-year continuous trial is proposed. The collection and selection of CTLV isolates, bioassays with graft-inoculation tests, development of a rapid RT-PCR assay for CTLV detection, and full genomic sequencing of several representative CTLV isolates will be carried out during the first year. The second year will focus on the preparation of monoclonal antibodies against CTLV, development of quantitative monitoring of CTLV by Real-time RT-PCR techniques, and further collections of foreign and domestic special CTLV isolates. During the last year, we expect to complete the categorization of CTLV strains, determine the phylogenetic relationships among the strains, develop the RT-PCR assay for specific detections of CTLV strains, survey the distribution of CTLV strains in Taiwan, and select good rootstock-scion combinations resistant (tolerant) to CTLV infection according to the results of inoculation tests. The first-year project obtained the NSC grant last year, and several satisfactory results have been harvested. Bioassays among four distinct CTLV strains collected from domestic and foreign areas demonstrated that they have different pathological characters. The full genomic sequences (totally 6496 bases) of two Taiwanese isolates, LCd-NA-1 (from Luchen sweet orange) and Kq-6-2-46 (from kumquat) have been determined and posted in GenBank (accession number AY646511). All trials proposed in the first-year project are smoothly conducting at present time, and a continuous project is proposed to apply the second and third-year grants for abundant and intensive harvests.
Citrus tatter leaf virus (CTLV)