Wild genes for wild climates

Imagine a plate of pasta, falafel or hummus – and you are by the Mediterranean. The ingredients – durum wheat, chickpeas and eggplant, plus garlic, olive oil and more – were all (except eggplant) cultivated in the region since the dawn of agriculture. The countries from Maghreb to Afghanistan are the world’s wheat civilizations. Durum makes pasta in Italy, bulgur in Turkey, couscous in North-Africa. With wheat bread, people eat up to three times the world average of wheat. With more people, more and more is imported and countries less self-reliant. Too often years are too dry and warm.

And warmer they will be – by 2100 up to 4.8 Celsius degrees are predicted for the Middle East. Can crop plants adapt to a tougher future? Then they need genes that make them withstand stress. We have long known that their wild relatives and progenitors, today confined to barren places, are places to look. Potato and tomato varieties already have wild genes in them that protect against diseases. But what about climates? There is an historical lesson: Some 8000 years ago in Iran a durum wheat was «seduced» by wild goat grass. The progeny, bread wheat or common wheat, is today the widest cultivated plant on the planet. The wild genes made it adapt to climates from Central Norway to New Zealand, Patagonia and the foothills of the Kilimanjaro.

Over the last 30 years, international genebanks like the International Maize and Wheat Improvement Center, https://www.cimmyt.org/ (CIMMYT) and The International Center for Agricultural Research in the Dry Areas, https://www.icarda.org/ (ICARDA) have repeated a thousand times what happened a few times near the Caspian Sea, producing new, more resilient wheat varieties. These new wheats now grow in fields all over the globe. But the «minor» crops – often staples for the poor – lag far behind in this agricultural development.

However, this is changing. A unique and global initiative funded by the Norwegian Agency for Development Cooperation (NORAD) has done just that through the project Adapting Agriculture to Climate Change: Collecting, Protecting and Preparing Crop Wild Relatives (https://www.cwrdiversity.org/), known as the Crop Wild Relatives (CWR) Project. The initiative is unique due to its large budget of USD 50 million and its long timeframe of 11 years, running from 2011 to 2021. It’s managed by the Global Crop Diversity Trust, in collaboration with genebanks, research institutes and national breeding programs all over the world.

This endeavor supported pre-breeding projects – a process that broadens the elite genepool by re-capturing lost beneficial genetic diversity – for 19 crops important for food security with more than 100 partners in 50 countries (https://www.cwrdiversity.org/project/pre-breeding/).

Durum wheat trials in Marchouch and Cooperative Tradi Bio Malika, Morroco, 2018 ©CWR Crop Trust-M.Major

Ahmed Amri at ICARDA. During is PhD studies, in the early1980s, he crossed durum wheat with wild Triticum araraticum, and in 2007 the variety Faraj was released in Morocco. To make a “civilized” wheat again takes time, but in the «drought of the century» in 2016, Faraj out-yielded the current check variety Karim by c. 70%, also due to a gene resisting the Hessian fly. Then came the variety Nachit in 2017. From its wild emmer progenitor, its deeper roots reach the water. Through cooling transpiration from the leaves, grains fill well despite the heat, and its extra yellow flour is an unexpected bonus for growers as well as eaters of couscous or pasta. Although to have 10-15% CWR genes makes durum plants tolerate more heat or drought, flour often gets paler, so breeding continues. This has involved both academics like Gill, CIMMYT, ICARDA, national agricultural research in the Maghreb including active on farmer testing

(see: https://acsess.onlinelibrary.wiley.com/doi/epdf/10.1002/csc2.20223 and https://acsess.onlinelibrary.wiley.com/doi/full/10.1002/csc2.20319)

In Bangladesh carrots have become very popular since the 1990s. In a country where 2/3 of calories and proteins come from rice, people frequently suffer from “hidden hunger”, the lack of microelements and vitamins. Half a carrot a day may counteract the lack of beta-carotene – the precursor of Vitamin A – a major cause of blindness in children. Originally from Central Asia, the carrot was grown for leaves (like parsley) or seeds (like caraway) and became a root crop (like parsley root) 900 years ago. From being an adapted winter crop, harvested before bolting in Spring, it went to northern latitudes 600 years ago as a summer vegetable, seeding next year. From there carrot seeds went to warmer countries, such as the tropical Bangladesh which is too hot, too dry and soils often saline. In the project stress tolerance wild carrots has been found that may enrich the base for new and adapted varieties. This has involved breeders and farmers in both Bangladesh, Pakistan and the US, where tolerance to heat has affected the California production in recent years. Through Dr. Philipp Simon from the USDA and University of Wisconsin, PhD students in all countries are involved, combining field data with genomics (see https://www.cwrdiversity.org/wild-carrot-and-stick/ and https://acsess.onlinelibrary.wiley.com/doi/full/10.1002/csc2.20333).

On-farm trials for salinity tolerance in CWE-Rice lines at the shrimp-rice production area in Bac Lieu province in the Mekong delta, wet season 2019; Osmotic stress screening to drought tolerance by PEG-6000 (0 and 20%) at seedling stage of CWR-rice line in Can Tho University Lab., Vietnam ©Dr.Tin

In the past 30 years, Vietnam has become a major rice exporter. Half the crop is grown in the 4.1 mill ha Mekong delta. Professional farmers reap three crops a year with modern varieties. Most seeds (80%) are home grown (farm-saved seeds), the commercial market supplies only 5-10%. It fails both in the desired range of cultivars, timely delivery and high prices. In contrast, 30% is supplied through >300 farmer operated cooperative seed clubs initiated by Dr. Huynh Quang Tin in Cantho University. Realizing the potential of participatory methods and enhancing farmer skills, this has resulted in many varieties tested, developed or multiplied by the club members. They are keenly aware of climate change and the need for adapted varieties. Some of the varieties have also been released also through national trials.

The coastal range rice fields suffer seasonal damage from salt intrusion. In the 2015 El Nino-induced drought, damage was extensive. In the rainy season, the Mekong usually pushes the saltwater back into the ocean, and the opposite in the dry season. Then many farmers raise one or two “crops” of high value shrimps. However, when rains resume, soils often are too salt for the rice. Traditional tolerant varieties are too late and low yielding. The Indian rice variety Pokkali is known to have tolerance, but can wild rice also be a source? Through the club network the CWR project tested 200 unfinished rice lines containing 10-15% genes from four types of wild rice not initially tested for salt tolerance. The lines were screened hydroponically in the University while farmers screened and discarded lines with undesirable agronomy (see https://acsess.onlinelibrary.wiley.com/doi/10.1002/csc2.20354). In the end the 12 best lines were tested on farm on coastline farms, with shrimps as a “pre-crop”). Several were high yielding in saline conditions will be tested and studied further (https://acsess.onlinelibrary.wiley.com/doi/full/10.1002/csc2.20405).

With the help from the CWR project new lentils, chickpeas and pigeon peas are in the pipeline. The latter is a typical poor woman’s crop, with minimal research and low yields, but progenies with wild genes are now in official trials in India.

In the Far-East, small animal husbandry farmers in Inner Mongolia (China) call to the university for seeds of alfalfa, the superior hay and pasture crop. The newly released CWR-derived variety Zhongcao No. 3, developed by Prof. Linqing Yu and released in 2019 can stand the cold and the drought (https://www.cwrdiversity.org/an-alfalfa-that-loves-the-cold/).

What made this possible is that when domesticated during the Stone Age, many genes were left behind – a genetic bottleneck. To use crop wild relatives means to reintroduce them. Wild traits we do not want, we now may remove through our knowledge of the genomes. Still it takes time. A lesson from this project is that valuable traits in the CWR cannot be predicted in advance, but that pre-bred lines with 10-15% wild in them have a lot to offer. Well, cannot new methods like gene editing speed this up? Yes, but still we need to know and have those genes.

After as little as 10 years the first from the CWR project are reaching fields and kitchens. Hopefully NORAD will decide to launch a new phase. In the mountain in Svalbard they will certainly be safe and cold, but the climate is changing outside.

Åsmund Bjørnstad
Norwegian University of Life Sciences (NMBU)
Member of the project advisory board

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