A plant disease spread by sap-sucking insects has been devastating olive and fruit orchards across southern Europe, but scientists are inching closer to halting its spread with the help of insect repelling clays, vegetative barriers and genetic analysis.
Potato virus Y is the most economically important and devastating aphid-transmitted virus, affecting both tuber yield and quality. The virus is also a major cause of seed potato degeneration, which leads to regular flushing out of seed potatoes after limited field production cycles. There is no remedy for this virus and once a plant becomes infected, it stays sick for life.
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
New research provides a better understanding of how chemicals thought to impart unique health benefits to plants in the cabbage family are broken down to promote growth in conditions lacking sufficient sulfur. This findings could aid in the future development of broccoli and cabbage varieties.
New research from has shed light on why some invasive plants make a better comeback after a fire, out-competing native species in the race for resources
The findings, published in Nature Communications, could help to improve revegetation efforts in regions affected by bushfires.
During bushfires, organic compounds called karrikins, named after the Noongar word ‘karrik’, meaning smoke, are produced from burning plant material. Karrikins soak into the soil with the first rain after a fire and stimulate the germination of buried seeds.
The scientists from UWA’s School of Molecular Sciences and the ARC Centre of Excellence in Plant Energy Biology examined more than 400 species, and found that some appeared to have developed an enhanced sensitivity to karrikins.
Lead researcher Dr Mark Waters said it was known that plants use a special receptor called KARRIKIN INSENSITIVE 2 (KAI2) to detect karrikins. However, unlike most plants that carry only a single type of KAI2, some species had more receptors.
“We looked at plants we knew responded well to karrikins and found that one of these, an Australian weed commonly called wild turnip (Brassica tournefortii), had three KAI2 receptors,”Dr Waters said.
“On closer examination we found that mutations in one of these three receptors were responsible for the improved karrikin sensing.”
Dr Waters said the scientists also found that by changing two amino acids in the KAI2 receptor of a plant they could turn it into a karrikin super-sensor.
“This is exciting because we have discovered a way in which KAI2 protein can evolve to change its sensitivity to karrikins,” he said. “It will be interesting to see if this discovery could be used in areas where revegetation efforts are needed.”
Of 400 plant species examined subsequently, the scientists found to their surprise that there were similar KAI2 mutations in nine species of flowering plants.
“One of these species is Hakea drupacea, an Australian native that has become an invasive weed in South Africa, and relies on fire to spread,” he said.
By understanding which native species are karrikin super-sensors the scientists hope their study can guide predictions of which plant species may germinate best when treated with karrikins and apply this knowledge to the revegetation of fire and mining-affected land.
Read the paper: Nature Communications
Article source: ARC Centre of Excellence in Plant Energy Biology
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.
Astronauts in space generally live on processed, pre-packaged space rations such as fruits, nuts, chocolate, shrimp cocktails, peanut butter, chicken, and beef to name a few. These have often been sterilized by heating, freeze drying, or irradiation to make them last and key a challenge for the US Space Agency NASA has been to figure out how to grow safe, fresh food onboard.
Tropical forest trees are the centerpiece of debates on conservation, climate change and carbon sequestration today. While their ecological importance has never been doubted, what has often been ignored is their ability to store cultural heritage. Using recent advances in scientific methods and a better understanding of the growth of these trees, researchers can now uncover, in detail, the growing conditions, including human management, that have occurred around these ancient giants over their centuries-long life span.
Reading the Basmati Genome Provides Clues for Growing Drought-Tolerant and Bacteria-Resistant Rice. Using an innovative genome sequencing technology, researchers assembled the complete genetic blueprint of two basmati rice varieties, including one that is drought-tolerant and resistant to bacterial disease.