New research from New Zealand promises to help breeding programmes for new onions tailored to grow in specific conditions.

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Onions, the third largest vegetable crop in the world, form a bulb in response to lengthening days, however the molecular mechanisms controlling this response were not previously well understood. Research undertaken by Plant & Food Research and the University of Otago, New Zealand has identified the gene controlling bulb development, which those leading the study said is the first step in discovering genetic markers that can be used as tools to screen conventional breeding programmes.

The research, published in the journal Nature Communications, will lead to the development of tailored new onion varieties with desirable genetic profiles, according to the study's authors.

"This research is an excellent example of how new genome technologies can enable major discoveries that, in the past, have been difficult," said Associate Professor Richard Macknight. "By understanding how these plants control development of the bulb, we can support the breeding of new cultivars that have the right genetic profile to respond to specific growing conditions, ensuring each plant produces a bulb for sale on the market."

Commercial production of onions relies on cultivars tailored to the environment they are grow in, responding to the right combination of day length and temperature to form a bulb. Around 90 million tonnes of onions are produced globally each year, but genetic studies of onions have been limited.

John McCallum of Plant & Food Research, added, "Our research is now beginning to link genetics and physiology of onions, allowing industry to tap into more diverse genetic resources and breed products adapted to different and changing environments."

Commercial growers in the EU produce 5.2 million tonnes of onions each year. Spain is the principal producer, accounting for around a fifth of these, though Germany, Denmark, France, the Netherlands and the UK are all major growing countries. Onion production declined in all of the EU's major production regions save for Spain this year, as production was hampered by challenging conditions.