Allan Brown, Hassan Mduma, Rony Swennen, IITA-Arusha
Producing seeds in banana for genetic improvement has always been a dauntless task, but some bananas are even more challenging to work with than others. The Mchare bananas, sometimes referred to as Muraru, Mlali, or Mshare, are diploid cooking bananas prized especially by the people of the Northern Tanzanian highlands but also in its neighboring countries including the east African islands. These bananas differ dramatically in texture and in genetic background from other, more familiar East African highland cooking bananas such as Matoke.
In the regions of Kilimanjaro, Arusha, and Mbeya these bananas can provide up to 30% of the caloric intake, bringing a premium price in the local markets. However, Mchare growers face serious obstacles as these bananas are susceptible to almost every major disease and pest of banana in Africa, as well as being particularly vulnerable to a new strain of Fusarium that has been reported in Mozambique.
The reduced fertility and parthenocarpy (seedless fruit development) of these bananas make them especially challenging to work with. Most people who have spent their lives consuming them have never seen a banana seed. The varieties currently grown by farmers in the region have never been the target of systematic genetic improvement and in many ways, likely represent the same bananas that their ancestors have been growing for hundreds of years. The work of IITA researchers in Arusha has documented variability in pollen viability among Mchare varieties (manuscript in preparation) which has allowed us to focus our efforts on those varieties that are most likely to successfully produce seed. However, even the most fertile Mchare only produces about 20% of the pollen observed in wild type bananas and female fertility is also greatly reduced. As many as 30 daily pollination can be required to produce a single seed. The challenges do not stop there. Only 17% of these seeds will germinate even using techniques such as embryo rescue. It is not an exaggeration to say that the production of these first Mchare hybrids is an extremely significant breakthrough.
In the past year, IITA along with our partners at the Nelson Mandela African Institution of Science and Technology (NM-AIST), has completed an expansion of facilities that include state-of-the-art facilities for tissue culture, pathology, and DNA analysis, with extensive pollination blocks established. The first fruit of this labor has resulted in the production of the first Tanzanian Mchare hybrids produced by hybridization with multiple disease resistant wild bananas.
Work will continue to evaluate the hybrids and determine if the resistance has been inherited and if the hybrids have retained the quality characteristics demanded by end users in the region. Unlike other bananas, Mchare is unique in that it is a diploid banana, and efforts will now focus on crossing these hybrids back to the original parents, recovering an optimal amount of the original quality while integrating multiple disease resistance. As the Mchare breeding program has only been operational at NM-AIST for the past 2 years, these first hybrids represent a significant step toward addressing serious food security issues in Tanzania.
Currently, we have established a collaboration with our host organization (NM-AIST) to develop a link to local farmers to facilitate the evaluation of texture and flavor characteristics of these bananas, which has never been accomplished before. The participation of the farmers will help ensure the quality characteristics of the bananas and soon ultimately lead to their successful adoption and dispersal.