Field evaluation of micropropagated bananas derived from plants containing Banana Bunchy-Top Virus

Abstract

Micropropagated bananas derived from Banana Bunchy-Top Virus (BBTV) infected plants, but displaying no symptoms of the disease, were established in the field. They were grown for three years and produced a plant crop and ratoon crops. No disease symptoms were observed. There was uncertainty as to whether

• micropropagation eliminated the virus from the material,

• the plants were symptomlessly infected, or

• the plants were somaclonal variants that suppress symptom expression.

To resolve this question, suckers from these plants and non-infected controls were established in pots and infected with aphids, Pentalonia nigronervosa Coq, collected from BBTV-infected plants. All plants produced characteristic Banana Bunchy-Top Disease (BBTD) symptoms in five months. In addition, samples collected from the original symptomless field plants were tested by DAS-ELISA using a polyclonal antibody specific for BBTV. No detectable levels of virus were found in any of the samples. These studies support the view that the symptomless plants were virus free and not symptomlessly infected or BBTV-resistant somaclones generated from micropropagation. Nevertheless there continues to be a need for caution in dissemination of micropropagated bananas, especially when obtained from regions where BBTV is known to occur.