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Genetic engineering for resistance to Panama disease and Banana Bunchy Top

James Dale: Queensland University of Technology

<div>Commercial and small-holder banana production is often severely limited by one or more diseases. This is particularly evident with the most popular banana cultivar, Cavendish, which accounts for more than 50% of the world banana production and virtually all of the banana export market. Two of the most devastating diseases affecting Cavendish are Fusarium wilt or Panama Disease tropical race 4 (TR4) and bunchy top caused by Banana bunchy top virus (BBTV). Both these diseases are extremely difficult to control and both are continuing to expand their geographical ranges. We are using genetic modification to generate Cavendish lines that are resistant to these two diseases. For TR4 resistance, we previously identified an NB-LRR gene from a wild diploid banana, <em>Musa acuminata </em>ssp <em>malaccensis</em> which was differentially expressed in resistant and susceptible seedlings of that diploid. We transferred this gene to Cavendish and took a number of transgenic lines through a three year field trial. At the completion of the trial, one line remained completely disease free while three other lines had high levels of TR4 resistance. The level of resistance was correlated with the level of expression of the R gene. For BBTV, we have taken an RNAi approach targeting three different virus genes. After glasshouse screens in Australia, we have taken promising lines through to a field trial in Malawi. After 12 months, a number of lines remain disease free.</div>