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United States Department of Agriculture

Agricultural Research Service

Research Project: DOMESTIC, EXOTIC, AND EMERGING DISEASES OF CITRUS, VEGETABLES, AND ORNAMENTALS (DEED)

Location: Subtropical Plant Pathology Research

Title: Virus movement within grafted watermelon plants

Authors
item Webster, Craig
item Kousik, Chandrasekar
item Hassell, Richard -
item Ling, Kai-Shu
item Turechek, William
item Adkins, Scott

Submitted to: American Phytopathology Society
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2012
Publication Date: August 1, 2012
Citation: Webster, C.G., Kousik, C.S., Hassell, R., Ling, K., Turechek, W., Adkins, S.T. 2012. Virus movement within grafted watermelon plants. American Phytopathology Society. 102:S4.133.

Interpretive Summary: Watermelon production in Florida is impacted by several viruses including whitefly-transmitted Squash vein yellowing virus (SqVYV), Cucurbit yellow stunting disorder virus and Cucurbit leaf crumple virus, and aphid-transmitted Papaya ringspot virus type W (PRSV-W). While germplasm resistant to some of these viruses has been identified, it remains a challenge to transfer this resistance into commercial watermelon cultivars. Using resistant germplasm as a rootstock offers the potential for quickly providing resistance to viral diseases. Commercial seedless watermelon scions (cv. Tri-X 313) were grafted onto resistant rootstocks and independently inoculated with SqVYV or PRSV-W. Severity of virus symptoms was recorded and virus presence above and below the graft union was determined by serological methods and reverse transcription-polymerase chain reaction. Grafting on resistant rootstocks was not effective in preventing SqVYV-caused watermelon vine decline in ‘Tri-X 313’ scions. Movement of SqVYV and PRSV-W across the graft union and into most rootstocks was detected, overcoming resistance to both viruses. SqVYV titer in the ‘Tri-X 313’ scions was found to be similar in both non-grafted and grafted plants, but was lower for some resistant rootstocks. These results demonstrate the ability of viruses to move into resistant rootstocks of grafted plants suggesting that rootstock breeding strategies may need to take this into account.

Technical Abstract: Watermelon production in Florida is impacted by several viruses including whitefly-transmitted Squash vein yellowing virus (SqVYV), Cucurbit yellow stunting disorder virus and Cucurbit leaf crumple virus, and aphid-transmitted Papaya ringspot virus type W (PRSV-W). While germplasm resistant to some of these viruses has been identified, it remains a challenge to transfer this resistance into commercial watermelon cultivars. Using resistant germplasm as a rootstock offers the potential for quickly providing resistance to viral diseases. Commercial seedless watermelon scions (cv. Tri-X 313) were grafted onto resistant rootstocks and independently inoculated with SqVYV or PRSV-W. Severity of virus symptoms was recorded and virus presence above and below the graft union was determined by serological methods and reverse transcription-polymerase chain reaction. Grafting on resistant rootstocks was not effective in preventing SqVYV-caused watermelon vine decline in ‘Tri-X 313’ scions. Movement of SqVYV and PRSV-W across the graft union and into most rootstocks was detected, overcoming resistance to both viruses. SqVYV titer in the ‘Tri-X 313’ scions was found to be similar in both non-grafted and grafted plants, but was lower for some resistant rootstocks. These results demonstrate the ability of viruses to move into resistant rootstocks of grafted plants suggesting that rootstock breeding strategies may need to take this into account.

Last Modified: 4/20/2014
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