Tag Archives: crops wild relatives

How to Strengthen the Immune System of Plants: biodiversity

n the past 150 years, the concentration of carbon dioxide in the atmosphere has risen from 280 parts per million (ppm) to 410 ppm. For farmers this is mixed news. Any change in familiar weather patterns caused by the atmospheric warming this rise is bringing is bound to be disruptive. But more carbon dioxide means more fuel for photosynthesis and therefore enhanced growth—sometimes by as much as 40%. And for those in temperate zones, rising temperatures may bring milder weather and a longer growing season. (In the tropics the effects are not so likely to be benign.) What is not clear, though, and not much investigated, is how rising CO2 levels will affect the relation between crops and the diseases that affect them…

Plant biology is altered substantially by a range of environmental factors. This makes it difficult to predict what effect a changing climate will have on particular bits of agriculture. Carbon dioxide is a case in point. It enhances growth of many plants but,  it also shifts the defences to favour some types of disease over others.

To make matters even more complicated, evidence is mounting that changes in temperature and water availability also shift plant immune responses. André Velásquez and Sheng Yang He, at Michigan State University, wrote an extensive review on the warfare between plants and diseases in Current Biology in 2018. They noted that though some valuable crops, such as potatoes and rice, experience less disease as moisture levels increase, this is not the case for most plants. High humidity, in general, favours the spread of botanical diseases. The same can be said for temperature—with some diseases, like papaya ringspot virus, thriving in rising temperatures while others, for example potato cyst, are weakened.

The problems are daunting, then, but there is a way to try to solve them… Genes which grant resistance to diseases that might become severe in the future need to be tracked down. Modern crops have been streamlined by artificial selection to be excellent at growing today. This means that they have the genes they need to flourish when faced with the challenges expected from current conditions, but nothing more. Such crops are thus vulnerable to changes in their environment.  One way to find genes that may alter this state of affairs is to look to crops’ wild relatives. Uncossetted by farmers, these plants must survive disease by themselves—and have been fitted out by evolution with genes to do so. Borrowing their dna makes sense. But that means collecting and cataloguing them. This is being done, but not fast enough. The International Centre for Tropical Agriculture, a charity which works in the area, reckons that about 30% of the wild relatives of modern crops are unrepresented in gene banks, and almost all of the rest are underrepresented….

[This is becuase] most countries are, rightly, protective of their genetic patrimony. If money is to be made by incorporating genes from their plants into crops, they want to have a share of it. It is therefore incumbent on rich countries to abide by rules that enable poor ones to participate in seed collecting without losing out financially. Poor, plant-rich countries are in any case those whose farmers are most likely to be hurt by global warming. It would be ironic if that were made worse because genes from those countries’ plants were unavailable to future-proof the world’s crops.

Excerpts from Blocking the Road to Rusty Death: Climate Change and Crop Disease, Economist,  Apr. 20, 2019

Radical New Potatoes

Potatoes are already a staple for 1.3 billion people… but unlike other major crops, however, the potato has not had a breeding breakthrough of the kind that helped dramatically boost yields during the Green Revolution of the 1950s and 1960s. The reason is that creating a new potato variety is slow and difficult, even by the patient standards of plant breeders…Readying a new potato variety for farm fields can take a decade or more.  Many countries continue to plant popular potato varieties that have remained essentially unchanged for decades. But new approaches, including genetic engineering, promise to add more options. Potato breeders are particularly excited about a radical new way of creating better varieties. This system, called hybrid diploid breeding, could cut the time required by more than half, make it easier to combine traits in one variety, and allow farmers to plant seeds instead of bulky chunks of tuber

Solynta Hybrid Potato Seeds

To breed a better potato, it helps to have plenty of genetic raw material on hand. But the world’s gene banks aren’t fully stocked with the richest source of valuable genes: the 107 potato species that grow in the wild. Habitat loss threatens many populations of those plants. In a bid to preserve that wild diversity before it vanishes, collectors have made their biggest push ever, part of a $50 million program coordinated by the Crop Trust, an intergovernmental organization based in Bonn, Germany.

The Crop Trust has provided grants and training to collectors around the world. The effort on wild potatoes, which wraps up this month, has yielded a collection representing 39 species from six nations: Peru, Brazil, Ecuador, Guatemala, Costa Rica, and Chile. Zorrilla’s team alone found 31 species in Peru, including one for which no seeds had ever been collected. They plan to continue to search for four other species still missing from gene banks. “We will not stop,” she says. The plants are being stored in each nation’s gene bank, CIP, and the Millennium Seed Bank at the Royal Botanic Gardens, Kew, in the United Kingdom. The stored seeds will be available to potato breeders worldwide.

THE HARDEST PART comes next: getting desirable genes from wild species into cultivated potatoes….Other researchers are skirting the limitations of traditional breeding by using genetic engineering. CIP’s Marc Ghislain and colleagues, for example, have directly added genes to already successful potato varieties without altering the plants in any other way—an approach not possible with traditional breeding. They took three genes for resistance to late blight from wild relatives and added them to varieties of potato popular in East Africa.

Potato Blight , a disease affecting potatoes

The engineered varieties have proved successful in 3 years of field tests in Uganda and are undergoing final studies for regulators. Transgenic potatoes that resist late blight have already been commercialized in the United States and Canada….

Pim Lindhout has been plotting a revolution that would do away with much of that tedium and complexity. As head of R&D for Solynta, a startup company founded in 2006, he and his colleagues have been developing a new way to breed potatoes….Breeders reduce the complexity either by using species with only two sets of chromosomes (known as diploids) or by manipulating domesticated potatoes to cut the number of chromosomes in half. With persistence, diploid potatoes can be inbred. In 2011, Lindhout published the first report of inbred diploid lines that are vigorous and productive. More recently, Jansky and colleagues also created inbred diploid lines.

Such diploid inbred plants are at the heart of Solynta’s strategy to revolutionize potato breeding. Other firms, including large seed companies, are also working to develop hybrid potatoes. HZPC in Joure, the Netherlands, has begun field trials in Tanzania and in several countries in Asia.

Excerpt from Erik Stokstad, The new potato, Science, Feb. 8, 2019

Loss of Giraffes

Over 700 newly recognised bird species have been assessed for the latest update of The IUCN Red List of Threatened Species, and 11% of them are threatened with extinction. The update also reveals a devastating decline for the giraffe, driven by habitat loss, civil unrest and illegal hunting. The global giraffe population has plummeted by up to 40% over the last 30 years, and the species has been listed as Vulnerable on the IUCN Red List.

Today’s IUCN Red List update also includes the first assessments of wild oats, barley, mango and other crop wild relative plants. These species are increasingly critical to food security, as their genetic diversity can help improve crop resistance to disease, drought and salinity…Almost every species of plant that humans have domesticated and now cultivate has one or more crop wild relatives. However, these species have received little systematic conservation attention until now.

The update was released today at the 13th Conference of the Parties to the Convention on Biological Diversity (CBD COP13) in Cancun, Mexico. The IUCN Red List now includes 85,604 species of which 24,307 are threatened with extinction. “Many species are slipping away before we can even describe them,” says IUCN Director General Inger Andersen.

Excerpts from New bird species and giraffe under threat – IUCN Red List, News Release, Dec. 8, 2016