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ARS Home » Northeast Area » Kearneysville, West Virginia » Appalachian Fruit Research Laboratory » Innovative Fruit Production, Improvement, and Protection » Research » Publications at this Location » Publication #383652

Research Project: Improving Fruit Crop Traits Through Advanced Genomic, Breeding, and Management Technologies

Location: Innovative Fruit Production, Improvement, and Protection

Title: Robust response to plum pox virus infection via plant biotechnology

item BRIARD, PASCAL - Inrae
item SCORZA, RALPH - Retired ARS Employee
item Callahan, Ann
item ZAGRAI, IOAN - Fruit Research & Development Station Bistrita - Romania
item KUNDU, JIBAN - Crop Research Institute - Czech Republic
item Dardick, Christopher - Chris

Submitted to: Genes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2021
Publication Date: 5/27/2021
Citation: Ravelonandro, M., Briard, P., Scorza, R., Callahan, A.M., Zagrai, I., Kundu, J., Dardick, C.D. 2021. Robust response to plum pox virus infection via plant biotechnology. Genes. 12(6).

Interpretive Summary: A plum pox virus resistant tree, ‘HoneySweet’ was the product of inserting the gene for the virus’ coat protein. The gene rearranged in the plant and because of this a high level of resistance to the virus was obtained through a natural plant resistance mechanisms known as RNAi. To test that this rearrangement was the source of the resistance, it was transferred to another tree. To test this, tree was crossed with a tree that produced the viral coat protein but was not resistant. This resulted in 4 seedlings that contained the transgenes from both parents. All four of these seedlings were resistant to plum pox virus and all four had the resistance mechanism of RNAi targeting the coat protein gene. This demonstrated that the original rearrangement was responsible for the resistance of ‘HoneySweet’ and could be transferred to other plums to confer resistance.

Technical Abstract: To knock down plum pox virus, the plum pox virus coat protein was targeted by gene silencing through the combination of a susceptible plum expressing the plum pox coat protein and a resistant plum containing a hairpin arrangement of the plum pox coat protein gene. Clone C-2 is a transgenic plums expressing the coat protein (CP) from plum pox virus (PPV). Purposely silencing this CP gene expression was the challenging target of this study. Here, we verified, in planta, the effects of the inverse repeat of the plum pox coat protein sequence split by an hairpin an Inverted Repeat Silencing Hairpin (IRSH), that was characterized in the Honeysweet plum. Trusting with the role of the two CaMV35S (Cauliflower Mosaic Virus) promoter flanking the CP sequence, challenging assays to PPV infection corroborated the effectiveness of this IRSH introduced in the C1738 clone. In order to study the effect of this IRSH PPV CP, hybridizations were made with the resistant C1738 clone used as male parent with the susceptible C-2 clone expressing the coat protein, as female. Four of the resulting 63 clones were silenced and resistant to plum pox virus. While the crossing barriers due to the heterozygous character are among the limiting factors, the silencing induced by the IRSH PPV CP is robust. Extensive studies, in greenhouse containment, demonstrated that the C1738 clone is a plum readily silencer. In addition, these were verified through the virus transgene pyramiding in the Bluebyrd BO70146 plum that successfully produced resistant BC1738 hybrid plums.