A new pathotype of pepper mild mottle virus (PMMoV) overcomes the L4 resistance genotype of pepper cultivars

The biological, serological, and molecular characteristics of a newly isolated L-4 resistance-breaking isolate of Pepper mild mottle virus (PMMoV) were studied. The new pathotype of PMMoV is closely related to the Israeli pathotypes P-1,P-2 and P-1,P-2,P-3 of the virus; however, the mosaic symptoms caused by this new pathotype on pepper plants with an L-4 genotype were more severe than the mild mosaic symptoms caused by other common pathotypes of the virus in susceptible plants. The predicted amino acid sequence of the putative coat protein (CP) of the newly described pathotype has two amino acid mismatches when compared with the CP of pathotype P-1,P-2, leucine to glutamine at position 47, and alanine to glycine at position 87. The CP of the new pathotype has one amino acid mismatch when compared with P-1,P-2,P-3, having alanine instead of glycine at position 87. Based on its biological characteristics, the new pathotype was designated P-1,P-2,P-3,P-4 of PMMoV-Is. A method is described for the differentiation among the three PMMOV pathotypes using restriction cleavage analysis of reverse-transcription polymerase chain reaction products made from virus-infected plants. An additional unique Mn/I site in the CP gene of the newly isolated P-1,P-2,P-3,P-4 allows its distinction from the other two isolates, while BglI cleaved only products of the P-1,P-2 pathotype.