A new study reveals that oak trees can keep photosynthesizing for months after growth ends, challenging assumptions about how effectively forests convert absorbed carbon into long-term storage. A tree can look busy long after it has stopped building itself. Its leaves may still be absorbing sunlight and pulling carbon dioxide from the air, but deep [...]

Oak trees fight caterpillars by delaying spring just long enough to leave them hungry. In spring, forests usually burst to life right as insects hatch. Caterpillars, in particular, emerge when fresh leaves are young, soft, and packed with nutrients. This timing provides them with an immediate food supply and allows them to begin feeding right [...]

Deep in Taiwan’s misty mountains, researchers have confirmed the tallest tree in the country: a thousand-year-old fir tree higher than a 20-story building, which they’ve named “the heaven sword of the Da’an River.” Climbers scaled the tree and dropped a measuring tape from the top to the forest floor during the Lunar New Year holiday in January 2023. The tree measured 84.1-meters (276-feet). The findings have been published in Frontiers in Forests and Global Change. A team of ecologists, geologists, remote-sensing specialists, professional climbers and Indigenous people that calls itself the “Taiwan tree seekers” began the search in 2014. “The common characteristics [of the team] are probably that we are all tree lovers and like adventures,” Rebecca Chia-Chun Hsu, lead author from Division of Forest Ecology, Institute of Taiwan Forestry Research, told CNN. ‘The Heaven Sword’, Taiwan’s tallest tree, measures 84.1 meters. Photo courtesy of Steven Pearce. Taiwan is one of the few places on Earth where trees can grow this tall. The island sits where the tropics meet the subtropics, and its mountains host several giant conifer species. The species behind the new record, Taiwania cryptomerioides, is known to the Indigenous Rukai people as “the tree that hits the moon.” Although nearly 60% of Taiwan is covered in forest, loggers cleared much of the island’s old-growth forest between 1912 and 1991. However, its steep slopes were too dangerous to reach, and pockets of ancient forest survived. Still, finding the tallest tree amid the rugged terrain was a task. Taiwan…This article was originally published on Mongabay

Brown rot is a common fungal disease in the Southeastern United States that affects stone fruits like peaches, cherries, and plums. Monilinia fructicola is a tan, fuzzy fungus that grows on tree flowers, twigs, and fruit, and is the most common cause of brown rot. Once brown rot infects a tree, the damage is irreversible, causing significant crop losses in commercial orchards. Farmers try to control the spread of M. fructicola by applying chemical sprays, called fungicides, to fruit trees in the spring.

In M. fructicola, a biosynthesis gene named MfCYP51 encodes a major protein critical to the fungi’s survival. Certain fungicides, called demethylation inhibitor (DMI) fungicides, stop M. fructicola from growing by targeting this protein. Over the last 20 years, DMI fungicides have become less effective against brown rot as M. fructicola becomes more resistant. 

Living microorganisms and their metabolites can control fungal diseases as an alternative to chemical fungicides, known as biofungicides. Many bacteria produce compounds like hydrogen cyanide and pyrrolnitrin that damage fungal cells. However, scientists have not found a biofungicide suitable for commercial production.​ A group of researchers at Clemson University in the USA and Huazhong Agricultural University in China set out to test whether the soil bacteria Pseudomonas chlororaphis and Bacillus subtilis could be effective biofungicides against brown rot. 

The researchers performed an incubation experiment to analyze how the fungal cells make their critical protein from the MfCYP51 gene, a process called gene expression, under different fungicide treatments. They used 3 M. fructicola strains sensitive to traditional DMI fungicides and 3 resistant strains. They tested these with 5 different fungicide treatments: a DMI fungicide, a mixture of P. chlororaphis metabolites, a mixture of living B. subtilis cells, a DMI fungicide + P. chlororaphis metabolites, and a DMI fungicide +  B. subtilis cells. They also set up a control treatment with sterile water instead of fungicide.  

After 6 hours, the researchers extracted the molecule that measures gene expression, called RNA, from the fungi. They found that both the P. chlororaphis treatment and the DMI fungicide + P. chlororaphis treatment substantially reduced MfCYP51 expression in both the sensitive and resistant isolates compared to the controls. In contrast, the DMI fungicide, B. subtilis, and DMI fungicide + B. subtilis treatments increased MfCYP51 expression in the resistant isolates. The researchers concluded that P. chlororaphis has a unique ability to reduce gene expression, unlike other biofungicides.

​To further investigate how the biofungicide treatments work, the team tested whether P. chlororaphis and B. subtilis produced the anti-fungal metabolite pyrrolnitrin. They added 1 milliliter of each treatment to a machine that separates and identifies liquid compounds using high pressure, called a high-performance liquid chromatograph. They found that the P. chlororaphis treatment contained pyrrolnitrin, so they hypothesized that it was responsible for reducing gene expression.

Additionally, the researchers tested their 5 treatments on brown rot in fruit. For each treatment, they took 10 Gala apples, washed and sterilized their surfaces, and sprayed them with the fungicides. After 24 hours, they poked holes in the apples with toothpicks and added 20 microliters of liquid containing M. fructicola cells to the poked holes. They placed the apples in a humid chamber for 5 days and measured the number and size of brown rot spots that developed on their surfaces. 

Despite decreasing MfCYP51 expression, ​the researchers found that P. chlororaphis treatment alone didn’t reduce brown rot disease compared to the control, but the DMI fungicide and B. subtilis treatments did. The mixed treatments of DMI fungicide + P. chlororaphis and DMI fungicide + B. subtilis both reduced brown rot disease compared to the control, but only the DMI fungicide + P. chlororaphis treatment prevented it. 

​The researchers concluded that although biofungicides may not be fully effective on their own, commercializing them could allow farmers to use less DMI fungicide. They explained that scaling back the use of DMI fungicides would slow M. fructicola resistance. Finally, they proposed that future researchers test biofungicide mixtures containing pyrrolnitrin in the field to observe real-world effects on stone fruit trees.

The post Using bacteria to fight fungal brown rot appeared first on Sciworthy.

Tom Akers and Joe Tanner are finally in the same class.

The two veteran space shuttle crew members were inducted into the US Astronaut Hall of Fame together on May 16. They could also have been in the same NASA astronaut selection group, too, had history played out a little differently.

In 1984, Tanner reported to the Johnson Space Center (JSC) to fly as an instructor pilot and then applied for the next class of astronaut candidates.

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