Integrated Tissue Culture, Thermotherapy and Chemotherapy for Production of Plum Pox Virus Free Peach Plants

Abstract

Peach plants infected with plum pox virus (PPV) suffer significant losses due to reduced fruit quantity and quality. In this work, an integrated protocol combining tissue culture, chemotherapy, and thermotherapy was developed to efficiently produce PPV-free micro-propagated peach plantlets (Prunus persicae cv. Florida Prince). The study evaluated several approaches for virus elimination, including meristem tip culture, thermotherapy either in vivo (dry or wet heat) or in vitro (37°C for 14 or 28 days), chemotherapy using different concentrations (10–40 mg/L) of virazole or thiouracil, and a combined therapy consisting of 20 mg/L virazole followed by thermotherapy at 37°C for 21 days. Meristem tip culture alone yielded low survival rates (2–15%) and limited virus elimination, achieving only 10% for meristems excised from in vivo plants and 20% for those derived from in vitro cultures. In vitro thermotherapy at 37°C for 28 days resulted in 60% virus elimination with 93% shoot survival, whereas in vivo heat treatments produced survival rates of only 20–30%. Chemotherapy with 30 mg/L virazole achieved 90% virus elimination but severely reduced plant survival to 28%, while 20 mg/L virazole gave 69% elimination with 79% survival; thiouracil was consistently less effective at all concentrations tested. The most successful outcome was achieved using the combined protocol of 20 mg/L virazole followed by thermotherapy for 21 days, which yielded 83% virus elimination with 77% plantlet survival, outperforming all individual treatments. In conclusion, the integration of chemotherapy with thermotherapy under in vitro conditions represents a highly effective strategy for producing PPV-free peach plantlets, and DAS- ELISA is recommended as a diagnostic tool. This integrated approach offers a practical solution for virus-free stone fruit germplasm production, supporting disease management, germplasm conservation, and international plant material distribution.