Association of Tomato leaf curl New Delhi virus with mosaic and leaf curl disease of Chrysanthemum and its whitefly cryptic species

Abstract

Leaf samples of chrysanthemum plants showing typical begomovirus symptoms of mosaic, mottling and downward leaf curl were collected from famer’s field in Karnataka state of India. The begomovirus infection was confirmed by PCR using specific primers in twenty two infected chrysanthemum samples and no amplification was observed in twenty two healthy chrysanthemum samples. The partial begomovirus genome (1.2 kb) sequencing indicates, twenty two infected chrysanthemum samples are infected with begomovirus (tomato leaf curl New Delhi virus, ToLCNDV). Therefore one representative sample was selected for complete genome amplification using RCA method. The complete genome amplified was cloned and sequenced. The Species Demarcation Tool (SDT) analysis of full genome of ToLCNDV showed maximum nucleotide (nt) identity of 89.2–97.6% (DNA A) and 87.7–96.3% (DNA B) percent with ToLCNDV infecting cucurbits. Based begomoviruses species demarcation criteria (91% nucleotide sequence identity), the virus infecting chrysanthemum is considered as a strain of ToLCNDV. The betasatellite amplified from the begomovirus infected chrysanthemum showed maximum nt identity of 89% with Tomato leaf curl Bangladesh betasatellite (ToLCBDB) infecting papaya in India. Further, break point recombination analysis showed that genome and betasatellite of ToLCNDV infecting chrysanthemum is recombinant with already know begomoviruses. The whitefly cryptic species predominantly present in the begomovirus infected chrysanthemum fields was identified as Asia-II-5 group. The significance of these findings is discussed.