Transgenic bananas appear to successfully resist a bacterial wilting disease and pest species that are devastating the critical food crop in tropical regions across the planet, according to a newly published scientific paper.
The research has tremendous implications for Africa, which produces about a third of the 145 million tons of banana grown globally each year and 72 percent of the plantains. Banana production is an important source of income and food security for small-holder farmers, who have experienced significant crop losses due to disease, especially in East Africa.
Researchers turned to genetic engineering for a solution because development of nematodes or banana Xanthomonas wilt (BXW)-resistant cultivars by traditional crosspollination techniques is hampered by the sterility of the polyploid genomes of cultivated banana and plantains, stated the paper, which was published March 29 in Food and Energy Security.
Transgenic banana grown in both glasshouses and confined field trials demonstrated 100 percent resistance to BXW. Disease resistance was achieved by transferring two resistance genes from sweet pepper into banana, both singly and as stacked traits. These genes have provided disease resistance in other plants, including tobacco, tomato, orchids, calla lily, and rice. Researchers also have identified several other potential transgenes that could confer resistance to BXW.
Several transgenic defenses against nematodes are in different stages of development, according to the paper. Confined field trials using cystatin and peptide defenses show strong potential for nematode resistance research that also could have positive implications for other crops affected by the destructive pest worms.
Currently, nematodes are controlled in commercial plantations by environmentally damaging pesticides that are not normally available to or suitable for small-holders in Africa, the paper stated. Small-holder farmers do not have sufficient land to rotate their crops.
The paper also reported that there is no risk of gene flow from transgenic banana plants to either wild or cultivated plants because most edible cultivars are sterile and therefore cannot cross-pollinate because they produce no seeds or pollen.
Leena Tripathi, a plant biotechnologist at the International Institute of Tropical Agriculture (IITA) in Nairobi, wrote the paper with assistance from Howard Atkinson, Hugh Roderick, Jerome Kubiriba and Jaindra N. Tripathi.
The research was funded by the United States Agency for International Development (USAID), the Biotechnology and Biological Sciences Research Council (BBSRC), the Department for International Development (DFID) and the CGIAR Research Program on Roots, Tubers and Bananas (RTB).