Transgenic East African Highland Banana Plants Are Protected against Radopholus similis through Host-Delivered RNAi

The burrowing nematode Radopholus similis is considered a major problem of intensive banana cultivation. It can cause extensive root damage resulting in the toppling disease of banana, which means that plants fall to the ground. Soaking R. similis in double-stranded (ds) RNA of the nematode genes Rps13, chitin synthase (Chs-2), Unc-87, Pat-10 or beta-1,4-endoglucanase (Eng1a) suppressed reproduction on carrot discs, from 2.8-fold (Chs-2) to 7-fold (Rps13). The East African Highland Banana cultivar Nakitembe was then transformed with constructs for expression of dsRNA against the same genes, and for each construct, 30 independent transformants were tested with nematode infection. Four months after transfer from in vitro culture to the greenhouse, the banana plants were transferred to a screenhouse and inoculated with 2000 nematodes per plant, and thirteen weeks later, they were analyzed for several parameters including plant growth, root necrosis and final nematode population. Plants with dsRNA constructs against the nematode genes were on average showing lower nematode multiplication and root damage than the nontransformed controls or the banana plants expressing dsRNA against the nonendogenous gene. In conclusion, RNAi seems to efficiently protect banana against damage caused by R. similis, opening perspectives to control this pest.

Automated summary

The burrowing nematode Radopholus similis is a major problem in banana cultivation, causing extensive root damage and toppling disease. This study showed that soaking R. similis in double-stranded RNA of specific nematode genes suppressed its reproduction. By transforming a banana cultivar with constructs for expression of RNA against these genes, the researchers found that the transgenic plants had lower nematode multiplication and root damage compared to non-transgenic controls or plants expressing nonendogenous gene RNA. This suggests that RNAi can effectively protect banana against R. similis damage.