Philippines: African savants beat black sigatoka

African scientists have beaten the black sigatoka scourge that has bedeviled banana growers in the continent for three decades. Researchers in Kampala, Uganda have reported that the confined field trials of a genetically modified (GM) banana with improved resistance to black sigatoka fungus showed enormous promise. The disease, caused by the fungus Mucosphaerella fijiensis, can cut fruit production by more than half if it is not controlled. Ugandan scientists undertook the research to find out the best way to combat the fungus, which is easily spread by airborne spores, rain, planting materials, irrigation water and even packing materials used in exporting the fruit. Black sigatoka has also been the bane of the $400-million Philippine banana export industry, particularly after opposition to aerial spraying of fungicide snowballed and both the Department of Health (DOH) and the Department of Agriculture (DA) balked in allowing the method for control of black sigatoka.

As a result, banana exporters are now faced with infestation, not only by black sigatoka but also by the deadly Fusarium wilt caused by a fungus that bores into the soil and continues to attack bananas for 50 years. Banana export industry sources claimed fusarium has invaded 3,000 hectares of plantations but official statistics revealed that about 600 hectares had been hit several years after the presence of fusarium was discovered by former Agriculture Secretary Domingo Panganiban and confirmed by a team from the University of the Philippines at Los Banos (UPLB.) African scientists said the dark leaf spots caused by the fungus eventually enlarge and merge in banana leaves, causing debilitation and the drying of the leaves. The team led by Andrew Kiggundu, head of banana biotechnology research at the Uganda’s National Agricultural Research Laboratories Institute (NARL) in Kawanda, analyzed 19 lines of GM bananas and found promise in five of them. Kiggundu said more research is needed to estimate the exact yield gains from using the resistant banana strain.

The scientists inserted genes for chitinase, an enzyme that breaks down chitin, a hard substance that makes up the cell walls of the invading fungi, and prevented them from attacking the banana cells to cause the disease. Laboratory tests confirmed that leaves from transgenic plants showed nearly complete immunity to the cultured black sigatoka fungi. Researchers collaborated closely with the Catholic University of Leuven in Belgium, which developed several banana lines to include the chitinase gene before being brought to NARL for testing. Settumba Mukasa, the resident banana expert in the department of crop science at Uganda’s Makerere University, said the field trials were significant and proved the new disease-resistant banana could be the best antidote to black sigatoka.

Source: businessmirror.com.ph