A hot topic in global agriculture research is to exploit use of Crop Wild Relatives to mitigate effects of climate change. What are these and why are they important?

According to NASA’s Goddard Institute for Space Studies,so far every month in 2016 has broken the temperature record for that month. In fact, the global temperature in March 2016 was 1.28 °C hotter than the baseline average for March from 1951 to 1980. Therefore, it is critical to identify and utilize sources of novel genetic variations with potential roles in climate change adaptation and food security that are not found in domesticated crops.

 

Simply put, a crop wild relative (CWR) is a relative of a commonly cultivated crop that was never domesticated. It lives in the wild and farmers did not adopt it as a variety that they sweetpotatowanted to cultivate. This could have been for a variety of reasons like taste or yield, or any number of reasons that made it undesirable.

 

However, CWRs have continued to grow in the wild. The fact that they thrive in the wild without intervention, and often in marginalized or harsh environments, is just one reason why researchers are curious about them. Another reason researchers might want to know more about these free agents is that we don’t know what we don’t know; they could hold hidden treasures.

 

There is a movement to preserve CWRs in genebanks to ensure they don’t disappear. New biotechnology approaches like genome sequencing and genome editing can help scientists identify genes in these plants that at some later date may make them desirable as sources for new traits to address arising abiotic stresses.

 

A great example of research going on at CIP is an examination of a CWR sweetpotato discovered in the deserts of Ica in southern Peru. “We noticed that, despite the arid environment, this sweetpotato was still green,” says Dorcus Gemenet, geneticist at CIP, who collected the sweetpotato from the field near Ica.

 

CIP Senior Scientist Awais Khan is also curious about this wild sweetpotato. “I want to know how it lives in such an extreme environment”, he says. “What traits does this plant have to allow it to survive that its domesticated relatives lack?”

 

Under the presumption that the wild relative of sweetpotato is drought tolerant, Khan set up a series of tests to observe how it performed when subjected to different environmental stresses. One such observation included observing how leaves that separated from the vine dried in comparison to common sweetpotato varieties from North America (Beauregard)

and Sub-Saharan Africa (Tanzania).

 

To do this, Khan set up time-lapse photography of these three different varieties. What he discovered was instructional. The desert variety leaf retained rigidity throughout the experiment while the two other varieties quickly wilted. Upon further investigation he found that the low number of pores on leaves (stomata), closure of pores in water-limited conditions, and presence of thick cuticle layer on leaf surface might be responsible for retaining water more effectively, by slowing transpiration rate. This adaptation was critical for this plant to survive in the desert, and could be of great use for domesticated varieties as they experience drier, more desert-like conditions in parts of Asia, Africa, and South America.

 

 

“Now we know that this sweetpotato wild relative has special qualities,” notes Khan, “if we can isolate the gene that enables this and insert it in a domesticated variety, we could improve that variety’s tolerance to hotter and drier conditions.” Which, as Khan notes, would be a great boon to farmers in terms of yield and subsequent income, food security and nutrition.

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