First Report of Impatiens necrotic spot virus on Spiderlily in China.

Abstract

Impatiens necrotic spot virus (INSV) (genus Tospovirus; family Bunyaviridae) is a devastating disease in the production of ornamental flowers (1). From 2007 to 2009, a survey of 10 major parks and recreation areas in Kunming, the capital of Yunnan Province, China, indicated that approximately 60 to 70% of Spiderlily (Hymenocallis littoralis Salisb.) plants from eight parks had symptoms of concentric ring spots and necrotic spots. Symptomatic plants were tested for INSV and Tomato spotted wilt virus (TSWV) with an immunostrip (Agdia Inc. Elkhart, IN). Results indicated that only the samples designated HDL were positive for INSV and all other samples were negative for both INSV and TSWV. Mechanically inoculated Emilia sonchifolia, Nicotiana glutinosa, Impatiens balsamina, and N. rustica showed chlorotic lesions, concentric rings, and severe necrosis, symptoms typical for INSV in these hosts. Electron microscope inspection found tospovirus-like spheroidal, enveloped particles that were 90 nm in diameter. Primer 5 software (Premier, Canada) was used to design 14 primers from GenBank Accession No. NC_003625 to amplify the L RNA, nine from NC_003616 to amplify the M RNA, and six from NC_003624 to amplify the S RNA. With total RNA extracted from infected plant tissue as templates in reverse transcription (RT)-PCR, these primers generated 29 target fragments of 250 to 900 bp. These fragments were cloned with the vector pMD19 simple-T vector (Takara Bio Inc., Dalian, China) and sequenced. The sequences of the clones were aligned with the software DNAman (version 2.5; Lynnon Biosoft, Quebec, Canada), showing that RNAs L, M, and S are 8,776 bp (GenBank Accession No. GU112505), 4,948 bp (GenBank Accession No. GU112503), and 2,875 bp (GenBank Accession No. GU112504), respectively. BLAST analysis of these Spiderlily INSV sequences against the NCBI sequence database indicated that the RdRp protein (L RNA) was 99.6% identical with the RdRp protein from an Italian isolate (No. DQ425094), the Nsm protein (M RNA) has 99.0% identity with the Nsm protein from an isolate from Italy (No. DQ425095) and one from the United States (No. NC_003616), the G1G2 polyprotein (M RNA) has 99.9% identity with the analogous protein from an Italian isolate (No. DQ425095), the N protein (S RNA) has 99.6% identity with the N protein from an Italian isolate (No. DQ425096), and the NSs protein (S RNA) has 98.7% identity with the NSs protein from an isolate from Japan (No. AB109100). To our knowledge, this is the first report of INSV on Spiderlily in China. Reference: (1) A. E. Whitfield et al. Annu. Rev. Phytopathol. 43:459, 2005.