Cause of the Scion Death in Green Pepper Grafting System by a Tobamovirus

Abstract

This experiment was attempted to investigate a cause of the scion death in green pepper grafting system. A tobamovirus particle examined in the rootstock of the sample but not in the scion showing necrosis. The virus isolated from the rootstock was identified as Pepper mild mottle virus (PMMoV), pepper tobamovirus pathotype P1.2. (PMMoV-2), by nucleotide sequence analysis and host plant reaction. The virus isolate infected systematically in 6 commercial rootstock varieties using for green pepper grafting seedling production. Green pepper varieties ``Long green mart`` and ``Daechan`` represented resistance to the virus showing local lesions only on the inoculated leaves and ``Manitda`` was systematically infected. In the experiment with grafting ``Long green mart`` or ``Daechan`` onto the those rootstocks, the upper leaves of the scions first showed vein necrosis and wilt symptoms 7 days after inoculation with PMMoV-2 on the cotyledon of the rootstock, following to the scion stem necrosis and then only the scion death. The virus was detected in the rootstock but not in the scion. However, ``Manitda`` of susceptible variety in the grafting system showed mottle symptom on the leaves of the scion but not necrosis on the plant. PMMoV-3 isolate, pepper tobamovirus pathotype P1.2.3, did not cause the scion death in the grafting system. All of the varieties were susceptible to PMMoV-3. These results suggest that the scion death is caused by infecting with pepper tobamovirus pathotype P1.2. in the green pepper grafting system combined with the susceptible rootstock and the resistance scion to the virus pathotype.

Keywords

• Grafting
• Green pepper
• Pathotype
• Resistance