SJ Snyman1,2, CH Cele1,2 and M Ghai2
1South African Sugarcane Research Institute, Private Bag X02, Mount Edgecombe 4300, South Africa; Sandy.snyman@sugar.org.za
2University of KwaZulu-Natal, School of Life Sciences, Westville Campus, Private Bag X54001, Durban 4000, South Africa
Virus elimination via cryo- or osmo-therapy has only been recently reported for sugarcane mosaic virus (SCMV). Cryotherapy offers the dual advantage of germplasm conservation and virus removal while osmotherapy (osmotic treatments without liquid nitrogen) is a suitable alternative treatment for those cultivars that do not recover well after cryo-treatment. In this study, in vitro shoot tips of cultivars N12, N19, N58, and NCo376 infected with sugarcane yellow leaf virus (SCYLV) and NCo376 co-infected with SCMV and SCYLV were tested for virus elimination using both of these techniques. Virus presence was determined by RT-PCR before and after treatment. Cryotherapy resulted in 100% of the recovered shoots being SCYLV-free in cultivars N19, N58, and NCo376 and 83% in N12 when compared with untreated material. Osmotherapy resulted in 58% (N12), 91% (N19 and N58), and 100% (NCo376) of shoots being clear of SCYLV when compared with untreated in vitro control plants (0-8%). A novel finding was that NCo376 co-infected with SCMV and SCYLV had 100% virus-free recovered shoots after cryotherapy and 92-100% healthy shoots after osmotherapy, compared with controls, which had 17-42% virus-free shoots. The described techniques for virus eradication offer a promising solution for the provision of clean vegetative planting propagules and safer germplasm exchange.