Molecular Detection and Phylogeny of The Bipartite Begomovirus Pepper golden mosaic virus Associated with Okra Leaf Curl Betasatellite in the Iresine herbstii Ornamental Plant in Egypt

Pepper golden mosaic virus (PepGMV), a whitefly-transmitted bipartite begomovirus, is one of the most important viruses infecting pepper plants in the Western Hemisphere, including the United States and Latin America. PepGMV was detected in Giza, Egypt and identified as (PepGMV-EG-GZ), infecting the ornament Iresine herbstii and inducing mosaic and leaf curl symptoms. PCR analysis of the virus genome confirmed its bipartite begomovirus nature and its association with the defective okra leaf curl betasatellite (OLCB), namely PepGMB (FJ436005). The GenBank Blastn analysis, phylogeny, and nucleotide pairwise sequence identity (PSI) showed the clustering of PepGMV-EG-GZ DNA-A (FJ416867) and DNA-B (FJ416868) with PepGMV-Mo-US:TX (AY928512) and PepGMV-D-US:TX (AY928514), respectively. PepGMV-EG-GZ DNA-A had 98.2% PSI with PepGMV-Mo-US:TX, suggesting it was a variant of PepGMV isolates. PepGMB clustered with several Egyptian defective betasatellites. PepGMB had a PSI of 96.4% with OLCB-squash (FJ455515), indicating that it was an isolate of OLCBs. PepGMB had PSIs of 61.1% and 65.9% with the intact OLCB and cotton leaf curl betasatellite (CLCuB) from Pakistan (AJ316029) and India (AJ316037), respectively, an indication of its different nature from these two satellites. On the other hand, the intact OLCB(s) from Egypt clustered with the intact OLCB and CLCuB from Pakistan and India, respectively, an indication of their origin in the Indian subcontinent and not in the Middle East. Nucleotide sequence analysis on PepGMB showed the presence of a satellite-conservative region stem-loop structure similar to the other betasatellites. The possible role of defective PepGMB in affecting symptom development in I. herbstii is discussed.