Harsh climates, poor soils, pest attacks, disease outbreaks – plants able to thrive in the wild have evolved natural adaptations to withstand these stresses.
The genes that make crop wild relatives robust are essential to secure the future of our food supply, say researchers at the World Vegetable Centre (AVRDC). Crop wild relatives are the source of vital genes for climate resilience and adaptability. Yet new research shows that habitat destruction, overharvesting, pollution, invasive species, and other concerns are causing these important species to disappear, the researchers warn.
“The wild relatives of crops are one of the key tools used to breed crops adapted to hotter, colder, drier, wetter, saltier and other difficult conditions,” said Colin Khoury, a scientist at the International Center for Tropical Agriculture (CIAT). Khoury and collaborators, including vegetable breeder Derek Barchenger and Genebank Manager Maarten van Zonneveld, both from AVRDC, have been investigating the status of wild relatives of vegetables including chile peppers, lettuce, carrots and cucurbits (pumpkin, squashes, zucchini and gourds). Van Zonneveld and collaborators are also exploring gaps in legume germplasm collections.
The researchers found that even with protection in the wild, many vegetable crop wild relatives require urgent safeguarding in genebanks to assure long-term survival: more than 65 per cent of wild pumpkins and more than 95 per cent of wild chili peppers are not well represented in genebanks.
More conservation work needs to be done to ensure these wild species are maintained in genebanks and are adequately protected in their natural habitats. The researchers have produced maps to show plant collectors and land managers where the most significant gaps are in terms of current conservation, including where to collect species in “hotspots” of diversity.
The wild relatives of vegetables have not been a priority for conservation compared to staple crops such as maize or rice. “Since they aren’t cereal commodities, vegetables get less attention, especially when it comes to their wild relatives,” said Khoury. Yet these are the very crops researchers should devoting more of their time for nutrition, health and sustainability.
The studies provide foundational information about the wild relatives of globally important vegetable crops. Chili peppers, pumpkins, carrots and lettuce are among the most widely consumed vegetables in the world, with the first three crops providing essential nutrients such as vitamin A and C.
Owing to the lack of research, vegetable crops are often less productive than grains and tubers. Vegetables are sensitive to change in temperature and rainfall, and vulnerable to pests and diseases — another reason why their wild relatives, the source of future crop improvements, must be protected, the researchers stress.
Vegetables are not the only crops that need support from a wild bunch of relatives. Legumes such as mungbean (Vigna radiata) are another important and cheap source of proteins and micronutrients in human diets. These crops fix nitrogen because of their symbiosis with Rhizobium bacteria, which also makes them attractive for soil improvement in farming systems.
Like vegetables, the genetic improvement of legumes has lagged behind cereal crops, and for the same reason: a lack of support for research, collection and description.
A recent study by van Zonneveld and collabors found 26 per cent of the 88 Vigna taxa reviewed require urgent germplasm collecting efforts because they are not available at all or are under-represented in genebanks.
Targeted Asian and Pacific countries for germplasm collecting efforts include India, Thailand, Myanmar, Sri Lanka, Australia and Taiwan. In Africa, research indicates Burundi, Benin, DRC Congo, and Madagascar as priority countries for Vigna germplasm collecting efforts.
For more information:
Khoury, C.K., Carver, D., Barchenger, D.W., Barboza, G.E., van Zonneveld, M., Jarret, R., Bohs, L., Kantar, M., Uchanski, M., Mercer, K., Nabhan, G.P., Bosland, P.W., Greene, S.L.. 2019. Modelled distributions and conservation status of the wild relatives of chile peppers (Capsicum L.). DIVERSITY AND DISTRIBUTIONS. online.
van Zonneveld, M., Rakha, M., Tan, S.Y., Chou, Y.Y., Chang, C.H., Yen, J.Y., Schafleitner, R., Nair, R., Naito, K., Solberg. S.Ø.. 2020. Mapping patterns of abiotic and biotic stress resilience uncovers conservation gaps and breeding potential of Vigna wild relatives. SCIENTIFIC REPORTS. 10:2111.