Banana Xanthomonas Wilt Resistant Bananas

Banana Xanthomonas Wilt (BXW) is also known as banana bacterial wilt (BBW) or enset wilt. It is a bacterial disease caused by Xanthomonas campestris and it is one of the most devastating diseases that can attack a banana.

After being originally identified on a close relative of banana, Ensete ventricosum, in Ethiopia in the 1960s, Banana Xanthomonas Wilt appeared in Uganda in 2001 affecting all types of banana cultivars. Since then Banana Xanthomonas Wilt has been diagnosed in Central and East Africa including banana growing regions of Rwanda, Congo, Tanzania, Kenya, Burundi, and Uganda. This wilt attacks all cultivars of banana causing up to $2.2 billion estimated annual loss.

A bacterial ooze is excreted from the plant organs and this is a tell-tale sign that Banana Xanthomonas Wilt may be present. Common symptoms on the fruit include a yellow-orange internal discoloration and premature ripening of the fruit. Other symptoms include a gradual wilting and yellowing of the leaves plus wilting of the bracts and shriveling of the male buds.
The spread of Banana Xanthomonas Wilt threatens the livelihood of millions of African farmers who depend on banana for food security and income. There are no commercial chemicals, biocontrol agents or resistant cultivars available to control Banana Xanthomonas Wilt.

The development of disease resistant banana cultivars remains a high priority and scientists have tried to insert genes from foodstuffs that have shown resistance to Banana Xanthomonas Wilt. Now, a banana, infused with plant ferredoxin-like amphipathic protein (Pflp)[1] or hypersensitive response-assisting protein (Hrap)[2] from green pepper, have exhibited strong resistance to Banana Xanthomonas Wilt in both laboratory and screenhouses. The Hrap and Pflp genes work by rapidly killing the cells that come into contact with the disease-spreading bacteria, essentially blocking it from spreading any further. The mechanism, known as Hypersensitivity Response, also activates the defense of adjacent and even distant uninfected plants leading to a systemic acquired resistance.

Field trials are now being held.

[1] Namykwaya et al: Transgenic banana expressing Pflp gene confers enhanced resistance to Xanthomonas wilt disease in Transgenic Research - 2012
[2] Tripathi et al: Expression of sweet pepper Hrap gene in banana enhances resistance to Xanthomonas campestris pv. musacearum in Molecular Plant Pathology - 2010

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