Plant Nematology at Leeds: Cooking Bananas and Plantains

EAHB plantation at NARL, Kawanda

 

Bananas and plantains, of the genus Musa, are the 4th most improtant food crop of sub-Saharan Africa (SSA) and a significant component of food security across the region. The majority of growers are subsistance farmers cultivating a few banana plants to provide food for their family and to be sold at the local market.

All edible bananas are sterile, the result of a cross breeding between two incompatible banana species. The most economically and nutritinally significant cultivars fall into three broad categories. Plantains, East African Highland bananas (EAHB) and dessert bananas. Plantains and EAHB cultivars produce large starchy bananas that require cooking before they are edible, so are known collectively as cooking bananas. Plantain cultivars are predominantly grown in western Africa, while EAHB cultivars are predominantly grown across eastern and central Africa. Dessert banana cultivars produce sweet bananas that require no cooking. The most economically significant banana cultivar is the dessert banana 'Cavendish', the banana that is sold in supermarkets across the world.

All banana cultivars are highly susceptible to a wide range of pest and pathogens, a consequence of the small genetic pool that bananas have to develop resistance to any new threat. One of the most significant pests of all bananas globally are plant parasitic nematodes. The two most significant nematode pests in SSA in terms of damage caused are Radopholus similis and Pratylenchus coffeae. Both are introduced pests, introduced on contaminated planting material brought from outside the continent. Other nematode pests of banana present in SSA are the native Pratylenchus goodeyi and species of Helicotylenchus, Meloidogyne and Rotylenchulus, though these species are less important economically. Global estimates of losses to nematodes in banana plantations average 20% but reach 40% or more across SSA where storms topple plants with rotten, nematode-infested root systems. Highly toxic nematicides are the only current means to control nematode infestations, but are unavailable to the majority of subsistance farmers in SSA.

Radopholus similisRoot CrackingToppled banana

Clockwise from top left corner: Radopholus similis; banana root damage (lesions) caused by nematode infestation; nematode infested banana plant toppled before its fruit could be harvested.

We currently have two projects within the lab to develop nematode resistant cooking banana in collaboration with partners in Uganda, the second largest producer of bananas globally. We are working with researchers at NARO on EAHB, funded by USAID as part of the ABSPII programme, and with Leena Tripathi at IITA on plantain, funded by DFID and the BBSRC through the SARID programme . We are using either the rice cystatin in EAHB or the maize cystatin in plantain, as well as the synthetic behavioural repellent peptide to produce stacked defences to ensure durability. Work is also underway to develop RNAi as an additional line of defense to be deployed along side the cystatin and repellent.

 

Banana GH Trial in LeedsField Trial at Namulonge

Establishing optimum protocol for challenge of banana with nematodes in the glass house at the University of Leeds and in the field.

Capacity building in Uganda is a significant aim of both projects. Scientists from NARO and IITA have recieved training in molecular biology techniques and environmental monitoring techniques both in Uganda and in visits to the nematology lab at Leeds. Our aim is to create the ability within Uganda to find their own solutions to the agricultural challenges present in Uganda and the wider region of sub-Saharan Africa.

 

RebeccaIn the lab in NARL, Kawanda

Two of the Ugandan researchers who have received training in Leeds and at the NARO laboratories at Kawanda, Uganda.