Category

Agriculture

How three genes rule plant symbioses

By | Agriculture, News, Plant Science

For billions of years life on Earth was restricted to aquatic environments, the oceans, seas, rivers and lakes.

Then 450 million years ago the first plants colonised land, evolving in the process multiple types of beneficial relationships with microbes in the soil.

These relationships, known as symbioses, allow plants to access additional nutrients. The most intimate among them are intracellular symbioses that result in the accommodation of microbes inside plant cells. A study recently published describes the discovery of a common genetic basis for intracellular symbioses.

Read More

A genetic map for maize

By | Agriculture, News, Plant Science

Researchers uncover the genetics of how corn can adapt faster to new climates

Maize is a staple food all over the world. In the United States, where it’s better known as corn, nearly 90 million acres were planted in 2018, earning $47.2 billion in crop cash receipts. 

But, under the effects of climate change, this signature crop may not fare so well. As the world tries to feed a population skyrocketing to nine billion by 2050, that has major implications. So, what can we do about it? The answer might be exotic. 

A multi-institutional team led by University of Delaware plant geneticist Randy Wisser decoded the genetic map for how maize from tropical environments can be adapted to the temperate U.S. summer growing season. Wisser sees these exotic varieties, which are rarely used in breeding, as key to creating next-era varieties of corn.

The research team included scientists from UD, North Carolina State University, University of Wisconsin, University of Missouri, Iowa State University, Texas A&M University and the U.S. Department of Agriculture-Agricultural Research Service. The resulting study, highlighted by the editorial board of Genetics, provides a new lens into the future viability of one of the world’s most important grains.

“If we can expand the genetic base by using exotic varieties, perhaps we can counter stresses such as emerging diseases and drought associated with growing corn in a changing climate,” said Wisser, associate professor in UD’s Department of Plant and Soil Sciences. “That is critical to ensuring ample production for the billions of people who depend on it for food and other products.” 

Modern maize strains were created from only a small fraction of the global maize population. This limited infusion of diversity raises concerns about the vulnerability of American corn in a shifting climate. The U.S. Department of Agriculture (USDA) seed bank includes tens of thousands of varieties, but many are just not being used. 

“We know that the tropical maize varieties represent our greatest reservoir of genetic diversity,” said study co-author Jim Holland, a plant geneticist with the USDA Agricultural Research Service at North Carolina State. “This study improved our understanding of those genetics, so we can use this information to guide future breeding efforts to safeguard the corn crop.”

Certain exotic strains of maize better handle drought or waterlogging or low-nitrogen soil, for example. But because these strains have evolved outside the U.S., they are not immediately suited to states like Delaware. So, exotics first need to be pre-adapted.

In prior work, Wisser and his colleagues showed how 10 years of repeated genetic selection was required to adapt a tropical strain of maize to the temperate U.S. Co-author Arnel Hallauer spent a decade adapting the population through selective breeding, so it could flourish in an environment like Delaware. 

“What’s so cool now is that we could go back to the original generations from Dr. Hallauer and grow them side by side in the same field,” Wisser said of the first-of-its-kind experimental design. “This allows us to rule out the influence of the environment on each trait, directly exposing the genetic component of evolution. This has opened a ‘back to the future’ channel where we can redesign our approach to developing modern varieties.”

While extremely impressive, a decade to adapt exotic maize to new environments is a lot of time when the climate change clock is ticking.

“Unfortunately, this process takes 10 years, which is not counting ongoing evaluations and integrating the exotic variations into more commonly used types of maize,” Wisser said. “With the climate threats we face, that’s a long time. So, gaining insights into this evolutionary process will help us devise ways to shorten the time span.”

Accelerating adaptation

Wisser isn’t wasting any time as he explores ways to bolster corn’s ability to survive and thrive. He and Holland are working on a new project to cut that time span in half. 

In cutting-edge research funded by the U.S. Department of Agriculture’s National Institute of Food and Agriculture, the team is analyzing how corn genomes behave in a target environment as they aim to formulate a predictive model for fitness.

“What we’re doing is sequencing the genomes and measuring traits like flowering time or disease for individuals in one generation. From this, we can generate a lookup table that allows us to foresee which individuals in the next generation have the best traits based on their genetic profiles alone,” Wisser said. “And our lookup table can be tailored to predict how the individuals will behave in a particular environment or location like Delaware.” 

That means plant breeders could grow a second generation of corn anywhere outside of Delaware, but still predict which individuals would be the most fit for Delaware’s environment. 

“For instance, even if the plants are grown at a location where a disease is not present, our prediction model can still select the resistant plants and cross them to enrich the genes that underlie resistance,” Wisser said. 

With this approach, researchers don’t have to wait out a Delaware winter, so they can continue to pre-adapt the population for at least one extra generation per year. That’s how 10 years of selective breeding for pre-adaptation could become five, providing a quicker route to access exotic genes. 

This new effort connects to the Genomes To Fields (G2F) Initiative, developed in 2013 for understanding and capitalizing on the link between genomes and crop performance for the benefit of growers, consumers and society. 

If Wisser and Holland can develop a method to rapidly pre-adapt exotics, this opens a lane for G2F to test the impact of these unique genomes on crop performance.

“Our goal is to advance the science so breeders can draw on a wider array of the diversity that has accumulated across thousands of years of evolution,” explained Wisser, who has been involved in the public-private initiative since its beginning. “In turn, they can produce improved varieties for producers and consumers facing the challenges of climate change.”

Read the paper: Genetics

Article source: University of Delaware

Author: Dante LaPenta

Image credit: Monica Moriak, Evan Krape, Teclemariam Weldekidan and Randy Wisser

New viable CRISPR-Cas12b system for plant genome engineering

By | Agriculture, News, Plant Science

In a new publication in Nature Plants, assistant professor of Plant Science at the University of Maryland Yiping Qi has established a new CRISPR genome engineering system as viable in plants for the first time: CRISPR-Cas12b. CRISPR is often thought of as molecular scissors used for precision breeding to cut DNA so that a certain trait can be removed, replaced, or edited. Most people who know CRISPR are likely thinking of CRISPR-Cas9, the system that started it all. But Qi and his lab are constantly exploring new CRISPR tools that are more effective, efficient, and sophisticated for a variety of applications in crops that can help curb diseases, pests, and the effects of a changing climate. With CRISPR-Cas12b, Qi is presenting a system in plants that is versatile, customizable, and ultimately provides effective gene editing, activation, and repression all in one system. 

“This is the first demonstration of this new CRISPR-Cas12b system for plant genome engineering, and we are excited to be able to fill in gaps and improve systems like this through new technology,” says Qi. “We wanted to develop a full package of tools for this system to show how useful it can be, so we focused not only on editing, but on developing gene repression and activation methods.”

It is this complete suite of methods that has ultimately been missing in other CRISPR systems in plants. The two major systems available before this paper in plants were CRISPR-Cas9 and CRISPR-Cas12a. CRISPR-Cas9 is popular for its simplicity and for recognizing very short DNA sequences to make its cuts in the genome, whereas CRISPR-Cas12a recognizes a different DNA targeting sequence and allows for larger staggered cuts in the DNA with additional complexity to customize the system. CRISPR-Cas12b is more similar to CRISPR-Cas12a as the names suggest, but there was never a strong ability to provide gene activation in plants with this system. CRISPR-Cas12b provides greater efficiency for gene activation and the potential for broader targeting sites for gene repression, making it useful in cases where genetic expression of a trait needs to be turned on/up (activation) or off/down (repression). 

“When people think of CRISPR, they think of genome editing, but in fact CRISPR is really a complex system that allows you to target, recruit, or promote certain aspects already in the DNA,” says Qi. “You can regulate activation or repression of certain genes by using CRISPR not as a cutting tool, but instead as a binding tool to attract activators or repressors to induce or suppress traits.” 

This ability gives CRISPR-Cas12b an edge over CRISPR-Cas12a, particularly when gene activation is the goal. Additionally, the system retains all the positives that were inherent in CRISPR-Cas12a for plants, including the ability to customize cuts and gene regulation across a broad range of applications. In fact, Qi and his lab were even able to repurpose the CRISPR-Cas12b system for multiplexed genome editing, meaning that you can simultaneously target multiple genes in a single step. 

“Added complexity allows targeting of more specific or other effectors for gene activation, repression, or even epigenetic changes,” says Qi. “This system is more versatile because we can play with more modifications, more domains, and there are therefore more opportunities to engineer the whole system. Only when you have this kind of hybrid system with more complexity do you get the most robust gene activation and editing capabilities.” 

The initial work for CRISPR-Cas12b completed in this paper was conducted in rice, which is already a major global crop. However, Qi and his lab hope to explore more systems to further enhance and improve plant genome engineering, including developing applications to additional crops. 

“This type of technology helps increase crop yield and sustainably feed a growing population in a changing world. In the end, we are talking about broad impact and public outreach, because we need to bridge the gap between what researchers are doing and how those impacts affect the world,” stresses Qi.

Read the paper: Nature Plants

Article source: University of Maryland

Author: Samantha Watters

Image credit: National Institutes of Health

Photosynthesis varies greatly across rice cultivars—natural diversity could boost yields

By | Agriculture, IRRI, News

A team of researcher examined how 14 rice diverse varieties photosynthesize—the process by which all crops convert sunlight energy into sugars that ultimately become our food. Looking at a little-studied attribute of photosynthesis, they found small differences in photosynthetic efficiency under constant conditions, but a 117 percent difference in fluctuating light, suggesting a new trait for rice breeder selection.

Read More

SCAM ALERT: We have received reports of a scam targeting GPC representatives

More information here
X