PCR diagnosis and in vitro sanitation of the papaya MSXJ hybrid with ringspot virus disease

Papaya (Carica papaya L.) is a tropical fruit with a high nutritional value. Current problems affecting its cultivation are the limited number of exploited varieties and its susceptibility to pests and diseases. The papaya MSXJ hybrid is resistant to pests and diseases, and its organoleptic characteristics are prominent compared with most papaya genotypes on the market. Samples of Papaya ringspot virus (PRSV) disease were evaluated by in vitro culture of the apical meristems and thermotherapy Sanitation of apical meristems was accomplished by regenerating them with or without light and thermotherapy was performed at 40 and 45 [degrees]C for 4 and 7 h, respectively. Both situations were observed for 45 d to evaluate survival, regeneration, and sanitation by reverse transcription polymerase chain reaction (RT-PCR). In vitro culture of the meristems in total darkness obtained the highest survival rate (87%) and regeneration (22%) compared with the treatments under photoperiod (21% and 18%, respectively). Under both study conditions, sanitation in PRSV was 100% of the meristems. Plants subjected to thermotherapy showed a higher survival rate (99.92%) at 40 [degrees]C for 4 h and sanitation of 80.2%. Key words: Apical meristems, Carica papaya, Papaya ringspot virus (PRSV), RT-PCR, thermotherapy.