Banana sustains … for nutrition, for livelihoods and for the environment

Banana sustains … for nutrition, for livelihoods and for the environment. About 500 people working with banana are meeting in Trichy, in South India, this week. I find it particularly exciting to have discussions with farmers and producers, and people from the industry, to hear about the real concerns now and for the future. I use these discussions to influence the directions of my own research and the ways I think about its use in the medium and longer terms.

As well as the producers, who are major conference sponsors, the majority of the people here come from research institutes along with University scientists. The industrial representation is strong: from the crop protection people, some impressive trickle irrigation systems to deliver water efficiently to the plant roots (Jain), storage and ripening chamber companies, and, as might be expected in India, several tissue culture companies providing millions of disease-free banana plants.

In the opening talk, HP Singh (‘Horticulture Promoting Singh’ as named by Jim Lorenzen, Uganda), the Deputy Director General of the Indian Council for Agricultural Research, presented a stimulating overview of horticultural and particularly banana research in India with a global perspective. India has 17% of the world’s population who are well-fed in a country with only 2.3% of the land area and 4.5% of the fresh water. Horticultural products account for more than 30% of the value of agriculture, and are a critical part of nutrition, food security and health. Yield has increased from 20 tons/ha in 1991 to 36 t/ha now, with critical contributions being new introductions with improved plant architecture, water and disease management, with a better post-harvest chain making better bananas more available and reducing losses.

At the exhibition, one of the farmers, Nathar Meeran, had bunches of Grand Nain (a Cavendish-type cultivar eaten widely in the West) from tissue-culture plants on display that weighed 83kg, nearly three times a typical fruit bunch, with 312 fingers on 16 hands.

A lot of pathology is being discussed too: even flying into Trichy airport, gaps were obvious in plantations where plants had been cut out to control disease. BBTV, banana bunchy top virus, is endemic in India and seriously constrains production, while the fusarium wilt, and particularly tropical race TR4 is a ever-present threat to many varieties here, in particular Cavendish types. I was interested to hear that the red thrip insect causes only cosmetic damage to fruit skin, with large black blotches. Surprisingly, there is no damage to the pulp from the insect, while my expectation would be the same plant response, mediated through ethylene, would both soften the pulp and give blacking of the skin. Post-harvest losses, another topic of the meeting, can reach 50% in some areas – a disaster for farmers, consumers and, after all the water, nutrients, crop protection and labour have been put into the crop, the environment too.

My general talk was on ‘Genomics, biodiversity and breeding in banana”, and is posted on the web at www.tinyurl.com/bananaGenomics . The first, and largest, section was about progress in understanding the genome – the chromosomes, DNA and chromatin – of banana. We now have many resources in gene (EST) sequences, knowledge of DNA polymorphisms and markers, BAC libraries and germplasm collections which are helping to advance this fundamental research, which is applicable to understanding disease resistances, abiotic stress responses or post-harvest losses. Measurements of the molecular DNA diversity in a few dozen of the 3000 or so banana cultivars are now available, information needs to be extended but is useful to find genetic traits such as disease resistance that will be useful and to reconstruct the ancestry of cultivars to ensure diversity is used and maintained. After several discussions (not least in the subtitle of the conference: “challenges from emerging biotic and abiotic stresses”) my final points discussed the concept of superdomestication (introduction in Annals of Botany, Vaughan et al. 2007 linked here), involving a partnership between farmers and producers with scientists to consider what is required in a new cultivar; this design is then passed to technologists to deliver using the most appropriate biodiversity and biotechnology. My thoughts about the social changes in farming and the ‘tragedy of the commons’ leading to environmental degradation have also lead to much discussion. 2009 marked the first year when less than half the world’s population were rural, so world-wide fewer and fewer farmers are feeding more and more people. In the production of new crop varieties, it is essential that these are suitable to grow with sustainable practices in soil conservation, water usage, and of course yield to minimize land used.

So the conference motto ‘Banana sustains …’ is certainly an accurate reflection of much of the work here. I hope these discussions will lead to better, more sustainable, banana production worldwide, with appropriate resistance to disease, adaptation to stress from climate, and waste-free distribution to consumers. All these requirements have a genetic basis, and I think that the application of genomic studies from many labs will help to meet the challenges.