Sunflower necrosis disease from India is caused by an ilarvirus related to Tobacco streak virus

Abstract

A serious disease of sunflower (Helianthus annuus) with putative virus aetiology was found occurring in all major sunflower-growing regions of India. Symptoms of this sunflower necrosis disease (SND) comprised chlorotic and necrotic ringspots and leaf distortion. A general leaf and stem necrosis extending to midveins, petioles and flower bracts eventually results in stunting and dieback, especially when plants become infected in the early stages of development.Ilarvirus-like particles were detected by electron microscopy in crude sap of SND-affected sunflower, and in Chenopodium quinoa plants inoculated with leaf extracts prepared from SND-affected sunflower plants. In addition to several other herbaceous virus indicator plants, groundnut, cowpea and cotton, significant crops in India, also became infected. Back-transmission to healthy sunflower seedlings with leaf extracts of systemically infected indicator plants resulted in identical symptoms of SND, confirming the ilarvirus-like component as the causative agent of sunflower necrosis disease.An antiserum (DSMZ AS-0615, Braunschweig, Germany) raised against purified virus preparations reacted well in DAS±ELISA and proved reliable for field diagnosis of Sunflower necrosis virus (SNV). In a comparative serological study using plants infected with other ilarviruses, a reaction was demonstrated only with Tobacco streak virus (TSV). This serological relationship was confirmed by Western blot analysis and by immunosorbent electron microscopy decoration assays using SNV and TSV antisera in reciprocal tests.In RT±PCR, using oligonucleotide primers deduced from conserved sequences within TSV RNA3 and flanking the entire coat protein region, an approximately 1000 bp dsDNA fragment was amplified from SNV-infected sunflowers. Sequence analysis of cloned SNV PCR fragments revealed nucleotide identities of approximately 90% with TSV RNA3 (EMBL accession number X00435) and a coat protein amino acid homology between SNV and TSV of more than 90%.

Emerging plant viruses in cotton

“…Telangana (India) recorded the highest incidence of TSV with 51.11 PDI in the hybrid RCH659, among locations including Tamil Nadu, Andhra Pradesh, Telangana and Maharashtra states of India (Vinodkumar et al, 2017) [69] . Earlier literatures reported TSV infection in crop plants such as, sunflower, groundnut, blackgram, cowpea (Prasada et al, 2009;Ramiah et al, 2001;Ravi et al, 2001;Bhat et al, 2002; Vemana and Jain 2010) [49,54,55,15,67] . Initial studies on TSV infecting cotton were attempted first by Arutselvan (unpublished, 2013) [10] in Tamil Nadu.…”

Management of Sunflower Necrosis and Sunflower Leaf Curl Diseases by Using Insecticides

“…It is caused by sunflower leaf curl virus which belongs to Begomo virus group and is infecting many crops. Symptoms of sunflower necrosis disease (SND) comprises of chlorotic and necrotic ringspots, leaf distortion, leaf and stem necrosis and eventual death" [3]. "The causal virus of the disease has been identified as Tobacco Streak Virus (TSV) and shown to be transmitted by thrips in the presence of infected pollen grains" [3].…”

“…Symptoms of sunflower necrosis disease (SND) comprises of chlorotic and necrotic ringspots, leaf distortion, leaf and stem necrosis and eventual death" [3]. "The causal virus of the disease has been identified as Tobacco Streak Virus (TSV) and shown to be transmitted by thrips in the presence of infected pollen grains" [3]. "The prominent symptoms of the Sunflower leaf curl disease observed were: small leaf size, malformed leaves, leaf and veinal thickening, enations and upward leaf curling.…”

The host range of Tobacco streak virus in India and transmission by thrips

“…Losses in peanut crops in the Ananthapur district of Andhra Pradesh, India, alone were estimated to exceed 42 million pounds. TSV was also shown to cause sunflower (Helianthus annuus) necrosis disease (SND) (Prasada Rao et al, 2000;Ravi et al, 2001). This investigation was undertaken to investigate the sources of inoculum, transmission of the virus by thrips that colonise flowers of TSV hosts and its seed transmission in peanut and sunflower.…”