- Author: Grace Fruto, UC Davis
- Author: Trina Kleist, UC Davis
Wildflower displays threatened
Northwest of Los Angeles, springtime brings native wildflowers to bloom in the Santa Monica Mountains. These beauties provide food for insects, maintain healthy soil and filter water seeping into the ground – in addition to offering breathtaking displays of color.
They're also good at surviving after wildfire, having adapted to it through millennia. But new research shows wildflowers that usually would burst back after a blaze and a good rain are losing out to the long-standing, double threat of city smog and nonnative weeds.
A recent study led by Justin Valliere, assistant professor in the UC Davis Department of Plant Sciences, found that native wildflowers and other plants that typically flourish following a fire were, instead, replaced by invasive plants on land that received the kind of nitrogen contained in vehicle emissions.
“Many native plants in fire-prone areas rely on fire, and some are entirely dependent on it. Some are even most abundant after a fire,” said Valliere, a UC Cooperative Extension specialist in invasive weed and restoration ecology. “But we found that these fire-following species may be especially vulnerable to the combination of nitrogen pollution and invasive plants.”
That's part of the reason why native plants in these mountains have been declining.
Seeds – banked in the soil and waiting to sprout
The problem faced by native plants can be compared to a drawn-down bank account: Funds withdrawn are not being replaced.
It starts with fire, an important ecological process, Valliere said. Flames burn through plants on the surface and return their nutrients to the soil. Seeds sleeping in the ground wait for the next rain to sprout, then use those nutrients to grow.
“Plant diversity is often highest in growing seasons immediately after a site burns,” he said.
But invading plants have many advantages over native ones. They often sprout earlier, grow faster and create more seeds, all while tolerating drought.
“They're like cheaters,” Valliere said. “They don't follow the same rules.”
Nitrogen, too, is an important piece of every plant's nutrition. They all get a fertilizing boost from nitrogen that floats up in vehicle emissions and falls to the ground. But the invaders use nitrogen and other nutrients to grow faster, winning the race for water and sunlight. As a result, fewer native plants reach maturity, producing fewer seeds that keep their populations thriving.
When the bank balance reaches zero
The 2013 Springs Fire gave Valliere a unique opportunity to study the combined impacts of wildfire and extra nitrogen. He and colleagues from UC Riverside and the National Park Service created test plots in the Santa Monica Mountains where the fire had burned. Then, they added nitrogen to the soil to mimic the amount and type that LA's smog would deposit. Over the study's three years, native plants that typically would have flourished after wildfire instead declined even faster in the plots with added nitrogen.
Native seeds sprouted, but didn't flower. Over time, the soil's bank of seeds drew down.
“Each seed has one chance to flower and reproduce,” Valliere said. “If a seed grows and gets outcompeted, that seed has lost its chance to replenish the seed bank.”
Without the chance to replenish their bank account, native plants will die out, and the whole ecosystem will be thrown out of balance.
“There is inherent value in biodiversity,” Valliere said. “These invasive weeds could prevent the re-establishment of native shrubs after fire, sometimes forever altering the plant community.”
The loss of native plants can have cascading effects on the larger environment, he added. Problems can include the loss of native bees that feed on the flowers, and mudslides when rain makes hillsides unstable.
This problem is likely to repeat in similar areas where biodiversity is highest after wildfires – including parts of the Mediterranean basin, southern Africa and Australia. The addition of city smog “could have serious consequences for the biodiversity of fire-prone ecosystems worldwide,” Valliere warned.
Read the paper, “Nitrogen deposition suppresses ephemeral post-fire plant diversity,” by Justin Valliere, Irina Irvine and Edith Allen.
This article was first published on the UC Davis Department of Plant Sciences website.
/h3>/h3>/h3>- Author: Kathy Keatley Garvey
It was right where it belonged--by the UC Davis Department of Plant Sciences.
As I returned from a meeting in the building today, something green caught my eye.
A praying mantis was hanging out on the society garlic.
Was it eating any prey? No, not this time. (Funny how we're always interested in the dining habits of praying mantids and their menu acquisitions.)
Society garlic or Tulbaghia violacea, is a native of South Africa, and emits a garlicky odor. It's a drought-tolerant plant especially popular now in California. The genus name, Tulbaghia, memorializes Ryk Tulbagh, an 18th-century Dutch governor of the Cape of Good Hope. And the species name? Violacea refers to the flower color, often described as pink, pinkish-violet or violet.
However, folks who want bee friendly plants don't plant this one. They lean toward such flowers as lavender, bee balm, African blue basil, zinnia, catmint and the like.
As for the praying mantis, it seemed to like the plant outside the UC Davis Department of Plant Sciences just fine.
We wonder if its breath smelled like garlic...
- Author: Diane Nelson
People often complain about grocery store tomatoes, saying they’re too hard and don’t have the flavor we remember from the days of old. And we thought we knew why - because the millions of tons of tomatoes harvested in the United States and beyond have to be picked before they’re fully ripe and juicy in order to survive being shipped long distances. What’s more, many shoppers store their tomatoes in the fridge, which destroys both their flavor and texture.
The news is unexpected and encouraging, because now breeders have the genetic information they need to create modern varieties suited for large-scale harvest and shipping with all the flavor of more delicate heirloom varieties.
“Now that we know that some of the qualities that people value in heirloom tomatoes can be made available in other types of tomatoes, farmers can have access to more varieties of tomatoes that produce well and also have desirable color and flavor traits,” Powell said.
It takes awhile to breed a new tomato variety, so don’t expect to taste the results anytime soon. But Powell and her team’s discovery is a huge first step. Tomato lovers can also be grateful for C.M. Rick Tomato Genetics Resource Center at UC Davis, home to a vast collection of mutant and wild species of tomatoes which provides the genetic diversity scientists and breeders need to recapture the flavor of old.
You can read more about the study here.
You can access the Science article here.
You can learn more about the C.M. Rick Tomato Resource Center here.
- Author: Diane Nelson
You know how it works: You stand in the grocery aisle, surreptitiously sniffing the cantaloupes, hoping your nose will lead you to a nice, ripe selection. But when you slice it open in your kitchen, it’s just not as ripe as you had hoped. Lucky for you (and me), UC Davis Department of Plant Sciences Assistant Professor Florence Negre-Zakharov and her team may have found a way to make imperfectly ripe fruit a thing of the past.
"We are involved in a project geared towards developing rapid methods to evaluate ripeness and flavor of fruits," explained Negre-Zakharov, who authored a paper on the method published in the March 30 edition of the Journal of Visualized Experiments (JoVE). "We evaluated an electronic nose to see if it can differentiate maturity of fruit, specifically melons. The goal is to develop a tool that can be used post-harvest to better evaluate produce, and develop better breeds."
When fruit ripens, it develops a characteristic volatile blend, indicating its maturity. Traditionally, the gold-standard of evaluating these volatiles has been gas chromatography, but it takes up to an hour to analyze a single sample, which makes it impractical to use outside the lab. Negre-Zakharov’s team wanted to determine if the much cruder — but much faster — electronic nose was able to determine if the melon they used in the experiment were ripe. It was.
"It’s quite encouraging technology for the purposes of determining maturity," she said.
"It's very impressive that the electronic nose system can do a type of gas chromatography in about a minute,” said JoVE science editor Zhao Chen. “Ultra-fast, indeed. Also, the sample preparation is as easy as making a smoothie at home. Such a user-friendly system could greatly help analysis efficiency in this field. Given the popularity of JoVE video-articles, I expect many researchers will know and adopt this method in their own research."
As a next step, the team is testing the electronic nose out in the field to see if it can still determine fruit maturity despite interference from all the background smells like soil and farm air. They hope to have results from those tests soon.
You can access a video of the study here.
- Author: Diane Nelson
While working in Tanzania on community development projects several years ago, Iago Lowe came to a life-changing conclusion:
Food security is central to projects that make a lasting difference in people's well-being. It ensures that communities have the seeds, soil, water and environment to produce enough to eat.
However, his bachelor's degree in physics and religion from Dartmouth College did not adequately prepare him to spearhead those kinds of projects.
To address that gap in his ability to "make some small difference in the world," Lowe started doctoral studies at UC Davis in 2007 in plant breeding and genetics.
"There are so many needs in developing nations — for schools, roads, water, other infrastructure — but when the money and people leave, so often the projects die," said Lowe, who completed his Ph.D. in Plant Breeding and Genetics at UC Davis in 2011. "The few projects I saw that continued to thrive, that really made a tangible difference in people's lives, almost always dealt with local food security, seed systems, soil and water conservation and ecological restoration — projects that demanded a set of skills I didn't have. After studying plant breeding at UC Davis and that's no longer the case."
Lowe exemplifies a new breed of plant breeders at UC Davis. Long a global leader in plant breeding, UC Davis has been retooling its programs — offering new training, creating new curriculum, hiring new faculty (as the budget allows) and conducting world-class research to meet a growing demand for new crops and for breeders.
The new generation of scientists that those programs will produce — and their research breakthroughs — can't come soon enough for industry, government and philanthropic foundation leaders who say that a shortage of plant breeders is hampering efforts to alleviate hunger around the world. Hundreds of high-paying industry jobs for plant breeders are going unfilled.
“Plant breeding is such a vital tool for helping us deal with significant challenges in the 21st century such as food security, population increase, urbanization, and water and energy shortages," said Xingping Zhang, a watermelon breeder with the Davis-based seed company Syngenta. "Who is going to educate the plant breeders? UC Davis is in a perfect position to do so because it's a great center of science and technological inventions, located right in the heart of agricultural abundance. No place in the world offers the diversity of crops [like those] grown in California."
In another major nod to UC Davis expertise, the U.S. Department of Agriculture awarded $40 million in grants earlier in 2011 to develop climate-change-tolerant plants and new bioenergy sources. UC Davis scientists will lead two research teams from more than 50 universities in more than 20 states.
"Each of these projects features transdisciplinary, regional, integrated teams, including scientists from institutions that represent underserved populations," said Roger Beachy, director of the USDA's National Institute of Food and Agriculture, in announcing the grants at UC Davis. "This approach represents a new paradigm in how USDA science can best solve critical issues facing agriculture today."
You can read more about the history and future of plant breeding at UC Davis in this article in the UC Davis Magazine.
Learn more:
UC Davis plant breeding education
Story on UC Davis Department of Plant Sciences website
Seed Biotechnology Center videos on plant breeding