How green pepper is saving East Africa's bananas

Two years since scientists transferred unique proteins from sweet green pepper into East African Highland Bananas to fight the deadly Banana xanthomonas wilt, farmers in the region are reporting double yields and near nil attacks,as scientists now laud the success of the simple technology as a breakthrough to even more crop disease control ventures.

The banana  wilt disease affects all banana varieties top among them the East African Highland bananas that are a staple food in most of the East African homes. It costs banana farmers about half a billion dollars in damage every year across East Africa, with the over 400,000 smallholder farmers in Kenya having grappled with the disease for the last decade. The leaves of the affected plants turn yellow and then wilt, and the fruit ripens unevenly and before its time. Eventually the entire plant withers and rots.

Before the discovery, there has been no commercial chemicals, biocontrol agents, or resistant varieties that could control the spread of the disease. Traditional methods to contain the disease were tedious and rigorous , with some of the control like de-budding, or removing the male bud as soon as the last hand of the female bunch is revealed requiring  rigorous sterilization of the tools to make sure that they do not spread the disease themselves. De-budding affects the quality of the fruit and sterilizing farm tools is a tedious task.

“Developing a truly resistant banana through conventional breeding would be extremely difficult and would take years, even decades, given the crop’s sterility and its long gestation period.” However, the two proteins – plant ferredoxin-like amphipathic protein (pflp) and hypersensitive response-assisting protein (hrap) – isolated from sweet green pepper have been shown to prevent the spread of the Xanthomonas bacterium in banana,” said Leena Tripathi, a molecular geneticist who was involved in the gene transfer.

The proteins work by quickly killing the cells that come into contact with the disease-spreading bacteria, essentially blocking the disease from spreading any further,” Tripathi says. “Hopefully, this will boost the arsenal available to fight BXW and help save the livelihoods of millions of farmers in East Africa.” This mechanism, known as hypersensitivity response, also activates the defenses of surrounding and even distant uninfected banana plants, leading to a systemic acquired resistance. These proteins can also provide effective control against other BXW-like bacterial diseases in other parts of the world.

Farmers in Uganda who are trialling the new banana variety say that the variety not only keeps off the revered disease but that they have noticed a considerable difference in yield growth. “I once cleared my whole acre of land due to this disease. Not even agro vets could tell what the disease it was. It has been every farmer's nightmare. But the new breed has produced some sought of magic. I have even recorded an increase of over 40kilos in my farms since I planted it,”said Jako Mugira a farmer in Tororo Uganda.
The scientists now hope to scale the new varieties to as many East African farmers as possible.