The world of agricultural science came out with some surprising news on Monday. An international consortium of scientists and researchers funded by the Global Crop Diversity Trust of Rome, Italy, announced findings that have gone against what was long held as an agricultural truth. The US is, contrary to long held belief, a fairly robust reservoir of plant diversity, especially among globally important food crops such as the sunflower, bean, sweet potato and strawberry plants.
The 4,600 recently discovered wild relatives of traditional food crops are regarded as welcome news for plant breeders, many of whom have relied upon them in recent years as new sources meant to combat disease resistance, drought tolerance and other traits.
The team published their findings in the most recent edition of the journal Crop Science.
Unfortunately, the good news is met with bad as well. Many of these ‘crop wild relatives’ are facing challenges like habitat loss, pollution and climate change. Lead author Colin Khoury of the International Center for Tropical Agriculture (CIAT) in Cali, Columbia cites a wild sunflower species used by breeders to restore fertility and create salt tolerance in the cultivated sunflower. This wild relative, along with 62 other taxa in the recently released inventory, is already listed under the US Endangered Species Act.
Khoury goes on to state that an estimated 30 percent of US plant species are now of “conservation concern”. The crop wild relatives tend to be even more vulnerable because they are often completely overlooked by both agricultural scientists and the conservation community. In addition to his work with CIAT, Khoury is also a doctoral student at Wageningen University in the Netherlands.
With this new detailed inventory, Khoury and his co-authors hope more attention will be paid to these wild strains. “We always say that crop wild relatives are important and that they’re threatened,” maintains Khoury. “I think what this study does is takes those general statements and puts some good evidence and documentation behind them.”
This is the first such inventory every completed for the US. Several European and Middle Eastern nations have completed inventories of their crop wild relatives and plans for their conservation. Much of this previous work is thanks to University of Birmingham plant scientist, Nigel Maxted, who has been a long time champion for the protection of these wild plants.
Khoury worked with Stephanie Greene of the USDA-Agricultural Research Service over the past four years. Their work has been to collect and identify as many species of wild plant as possible, including detailing what the species are, which crop plants they’ve been used to improve, how closely related they are to their respective crops, and whether any of the genetic resources found in crop wild relatives are already conserved in gene banks.
From their massive collection, the team then worked to prioritize the species using several criteria. While the bulk of the list is comprised of US wild relatives of the most important food crops like those listed above, other areas represented include forage crops like alfalfa; fiber crops such as flax and cotton; ornamental plants like roses and lilies; Echinacea, St. John’s Wort and other medicinal herbs; and varieties Khoury refers to as ‘iconic US crops,’ including sugar maple and wild rice.
The vast variety compiled and inventoried was surprising to the team. However, Khoury offers up several possible reasons for just why the US is the reservoir for these wild crops that it is. Firstly, while North America is not regarded as a major center for crop diversity, it is literally right next door to one that is – Mesoamerica. Just to our south, crops like corn, bean, squash and chili pepper find their origins. It is easy to understand how they might have migrated across borders. Also, Khoury points out many wild species in temperate parts of the US are genetically similar with crops, like hops and strawberry, which had already undergone domestication in other similarly temperate regions of the globe.
A full 12 percent of the taxa documented in this most recent inventory have been recognized as being non-native plants. Additionally, nearly five percent are listed as either federal or state noxious weeds. The team points out the viability of these plants, despite being non-native and potentially invasive, is important as they present valuable genetic resources for breeding. However, trying to protect and manage a plant regarded as a pest becomes more complicated.
The team points out that completion of the inventory was the first step. Now they must endeavor to figure out how to protect and manage US crop wild relatives. This next step will find Khoury, over the next year, analyzing the geographic distributions of the plants contained in the inventory. From there, he will determine whether or not they’ve been safeguarded in gene banks or in protected areas such as national parks. These determinations will lead him to then identify the priority locations for the collection of seed species that have yet to be secured.
Khoury, speaking on the time-sensitivity of this task stated, “The window for securing these plants so that they’re safe and can be used, it’s narrowing for sure. So, it’s really time to move forward and get these resources protected.”