An Engineered Citrus Tristeza Virus (T36CA)-Based Vector Induces Gene-Specific RNA Silencing and Is Graft Transmissible to Commercial Citrus Varieties.
Robert R Krueger, Angel Y S Chen, Jaclyn S Zhou, Si Liu, Huaying Karen Xu, James C K Ng
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引用次数: 0
Abstract
A protein-expressing citrus tristeza virus-based vector construct, pT36CA-V1.3, obtained from a California isolate of the T36 strain (T36CA), was retooled into a virus-induced gene silencing system intended for use with studies of California citrus. Virus-induced gene silencing constructs engineered with a truncated Citrus macrophylla PHYTOENE DESATURASE (CmPDS) gene sequence in the sense or antisense orientation worked equally well to silence the endogenous CmPDS gene. In a parallel effort to optimize vector performance, two nonsynonymous nucleotides in open reading frame 1a of pT36CA-V1.3 were replaced with those conserved in the reference sequences from the T36CA cDNA library. The resulting viruses, T36CA-V1.4 (with one amino acid modification: D760N) and T36CA-V1.5 (with two amino acid modifications: D760N and P1174L), along with T36CA-V1.3, were individually propagated in Nicotiana benthamiana and C. macrophylla plants. Enzyme-linked immunosorbent assay (ELISA) measurements of extracts of the newly emerged leaves suggested that all three viruses accumulated to similar levels in N. benthamiana plants at 5 weeks postinoculation. ELISA values of T36CA-V1.4- and -V1.5-infected C. macrophylla samples were significantly higher than that of T36CA-V1.3-infected samples within an 8- to 12-month postinoculation window, suggesting a higher accumulation of T36CA-V1.4 and -V1.5 than T36CA-V1.3. However, at 36 months postinoculation, the ELISA values suggested that all three viruses accumulated to similar levels. When C. macrophylla plants infected with each of the three viruses were grafted to commercial citrus varieties, a limited number of receptor plants became infected, demonstrating a weak but nonetheless (the first) successful delivery of T36CA to California-grown commercial citrus.
期刊介绍:
Phytopathology publishes articles on fundamental research that advances understanding of the nature of plant diseases, the agents that cause them, their spread, the losses they cause, and measures that can be used to control them. Phytopathology considers manuscripts covering all aspects of plant diseases including bacteriology, host-parasite biochemistry and cell biology, biological control, disease control and pest management, description of new pathogen species description of new pathogen species, ecology and population biology, epidemiology, disease etiology, host genetics and resistance, mycology, nematology, plant stress and abiotic disorders, postharvest pathology and mycotoxins, and virology. Papers dealing mainly with taxonomy, such as descriptions of new plant pathogen taxa are acceptable if they include plant disease research results such as pathogenicity, host range, etc. Taxonomic papers that focus on classification, identification, and nomenclature below the subspecies level may also be submitted to Phytopathology.