An unusual type of interference between two strains of bean common mosaic virus, viz. NY15 and NL3, infecting bean plants, was investigatred. Wdhen a primary leaf was inoculated with NY15 as inducer and 1–8 days later, the opposite leaf with NL3 as challenger, the plant did not develop symptoms characteristic of NL3, i.e. systemic necrosis in the top, stem and wilting and withering of the youngest trifoloclate leaves. A7‐h interval between the inoculations with inducer and challenger already sufficed to reduce the number of plants showing NL3 symptoms. Surprisingly, the amount of NL3 in the challenge‐inoculated leaf was always than that in the singly infected control, Furthermore, NY15 could not be detected in the opposite leaf until 8 days post‐inoculation and appered enen later in that leaf when challenge‐inoculated. Histological studies showed that NL3 appered later in the xylem of bothe the petiole and stem between primary leaves and first trifoliolate leaf, as compared with the singly inoculated control. The results suggest that suppression of Nl3 symptoms by Ny15 is not caused by impeding its multiplication, but by delaying the transport of NL3 to the xylem of petiole and stem.

This study presents the first whole genome sequence of Onion yellow dwarf virus (OYDV isolate RR1) from onion (Allium cepa) in India along with phylogenetic and recombination studies. We examined the sequence variability, distribution of simple sequence repeats (SSRs), and recombination breakpoints of different OYDV geographical isolates. The P1 and P3 regions of OYDV show a higher rate of sequence variability in amino acid and nucleotide sequences than other genomic regions. Entropy peaks of deduced amino acid sequences were higher in both regions (P1 and P3) of different OYDVs. The observed frequency of microsatellites was also higher in the P3 region of all OYDV genomes. The Indian isolate RR1 showed 75-98 % similarity with the other OYDV isolates in nucleotide and amino acid sequences and has 43 microsatellites and two compound microsatellites. It was most closely related to garlic isolate MS/SW1 from Australia. Isolate RR1 contained six recombination breakpoints in different genomic regions with the major parent related to the MS/SW1 (Australian) and SG1 (Spanish) OYDV isolates. The phylogenetic and recombination study demonstrated the divergence of Indian isolate RR1 from OYDV isolate from Australia.

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This research explores the spread of tomato spotted wilt virus (TSWV) on greenhouse and field grown ornamental species. A total of 152 samples have been examined. The identification of the virus has been conducted with conventional virological methods. The tomato spotted wi It virus has been detected in 25 flower species. Of them, 21 are new hosts for the coun!ly. Physostegia obtusifo/ia (Labiate) is a hitherto new TSWV host.

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