According to their research, published Sept. 23 in Current Biology, plants actually do have a way of talking to each other. Their messages come embedded in the form of airborne chemicals known as volatile organic compounds (VOCs), which transfer information among plants.
The big finding in the study is what Kessler calls “open-channel communication.” Based on their genotypes, different plants have different smells. But when plants come under attack from pests like the goldenrod leaf beetle, their smells – carried by VOCs – become more similar.
“So they kind of converge on the same language, or the same warning signs, to share the information freely,” Kessler said. “The exchange of information becomes independent of how closely related the plant is to its neighbor.”
The research found that neighboring plants pick up on warning VOCs and prepare for the perceived threat, such as an oncoming insect pest. Said Kessler: “A (VOC) emitted by one plant can be picked up by another plant, and they can either ready their defenses or they may actually directly induce those defenses.”
However, their goodwill toward plant neighbors only works on an if-you-see-something-say-something basis and when, as a result of the communication, pest pressure is equally distributed across the plant population. Plants in populations without herbivores do not freely share information with their neighbors. Instead, they maintain a private channel with their closest kin through VOC emissions that induce resistance – but only in those relatives or plant parts distant from the damage site on the same plant.
“We code our language if we want to keep it private, and that’s exactly what happens there, but on a chemical level,” Kessler said. “That analogy is striking and not what we expected.”
In the next month or so, orange trees across Florida will erupt in white blossoms, signalling the start of another citrus season. But this year, something different will be blowing in the winds. Farmers are preparing to spray their trees with hundreds of thousands of kilograms of two common antibiotics to combat citrus greening, a bacterial disease that has been killing Florida citrus trees for more than a decade.
The US Environmental Protection Agency (EPA) is in the process of allowing growers to use streptomycin and oxytetracycline as routine treatments, spraying trees several times per year, beginning with the ‘first flush’ of leaves this spring. Growers in the state could end up using as much as 440,000 kilograms of the drugs. Although the compounds, which are both used in human medicine, have been sprayed on other crops in the past and applied in limited amounts to citrus groves, the scale of this application has researchers and public-health advocates alarmed.
“They are doing a huge experiment with limited monitoring,” says Steven Roach, a senior analyst in Iowa City at Keep Antibiotics Working, a coalition of research and advocacy groups that has formally objected to the plan with the EPA.
( read more at Nature )
Surprisingly, dandelion seeds use a method of flight previously thought impossible.
Wind-dispersed plants have evolved ingenious ways to lift their seeds1,2. The common dandelion uses a bundle of drag-enhancing bristles (the pappus) that helps to keep their seeds aloft. This passive flight mechanism is highly effective, enabling seed dispersal over formidable distances3,4; however, the physics underpinning pappus-mediated flight remains unresolved. Here we visualized the flow around dandelion seeds, uncovering an extraordinary type of vortex. This vortex is a ring of recirculating fluid, which is detached owing to the flow passing through the pappus. We hypothesized that the circular disk-like geometry and the porosity of the pappus are the key design features that enable the formation of the separated vortex ring. The porosity gradient was surveyed using microfabricated disks, and a disk with a similar porosity was found to be able to recapitulate the flow behaviour of the pappus. The porosity of the dandelion pappus appears to be tuned precisely to stabilize the vortex, while maximizing aerodynamic loading and minimizing material requirements. The discovery of the separated vortex ring provides evidence of the existence of a new class of fluid behaviour around fluid-immersed bodies that may underlie locomotion, weight reduction and particle retention in biological and manmade structures.
Dandelion seeds fly using ‘impossible’ method never before seen in nature
Nature, Revealed: the extraordinary flight of the dandelion
Paper, A separated vortex ring underlies the flight of the dandelion
Research Gate project, The form and function of the dandelion fruit
Citrus canker is a disease that affects all citrus species and varieties. It is caused by Xanthomonas citri, a bacterium originally from Asia, where it is endemic in all citrus-producing countries. Although the bacterium can be combated in several ways, none is sufficient to eradicate the disease. Therefore, new chemical or biological methods of protecting citrus groves have to be pursued.
In an article published in Letters in Applied Microbiology, a team led by Daiane Cristina Sass, Lara Durães Sette and Henrique Ferreira, professors in São Paulo State University’s Bioscience Institute (IB-UNESP) in Rio Claro, Brazil, identify 29 fungi with proven action against X. citri. The origin of the fungi is surprising. They were isolated from samples of soil and marine sediment collected in Antarctica. read more…
Terrestrial and marine Antarctic fungi extracts active against Xanthomonas citri subsp. citri
Biotechnological potential of secondary metabolites from Antarctica fungi with activity against plant pathogenic bacteria
Feb 26 – Mar 2, 2018
Do you know what’s sneaking into your garden?
National Invasive Species Awareness Week
Aggressive Invaders in Texas
Texas Dept of Agriculture, Noxious and Invasive Plants
The Woodlands Invasive Species
Houston Arboretum and Nature Center
What traits make introduced plants likely to be invasive?
Similarity of introduced plant species to native ones facilitates naturalization, but differences enhance invasion success
Dodder vine is an amazing plant, it is orange rather than green due to its lack of chlorophyl, it can’t make its own food.
Instead the dodder vine hatches in the spring from a seed and very slowly moves in a circle searching the air for beta-myrcene a volatile chemical emitted into the air by tomatoes and other plants. When it picks up the scent of beta-myrcene it grows in the direction of the odor until it finds the plant emitting it.
Once it reaches the plant it tightly winds itself around the plant, sinking roots into the host plant. The roots then suck up the juices in the host plant to feed itself. The host plant will then wilt and die.
Dodder vine also appears to exchange RNA with the host plant. Whether this is a way of exchanging information with the host plant or a way to reprogram it, much the way viruses reprogram our DNA is unknown.
Plants use RNA as a way to send messages through out the plant. When a dodder vine attacks a plant some of the plant’s RNA gets sucked up by the dodder vine. The dodder vine can then read the RNA to better evaluate how to attack the host.
Professor Neelima Sinha and colleagues at the UC Davis Section of Plant Biology studied dodder vines growing on tomato plants in the lab. They found that RNA molecules from the host could be found in the dodder up to a foot (30 cm) from the point where the parasite had plumbed itself into the host.
Plants often use small RNA molecules as messengers between different parts of the plant. In a paper published in Science in 2001, Sinha’s group showed that RNA could travel from a graft into the rest of the plant and affect leaf shape. Plants can also use specific RNAs to fight off viruses. . . [ read more Plant Parasite Wiretaps Host ]
Dodder is a member of the Morning Glory family.
It has very tiny leaves that are more like scales than leaves and tiny white flowers.
It is considered an invasive plant and a threat to the local ecology in Texas.
A new method of plant communication?
Genomic-scale exchange of mRNA between a parasitic plant and its host
YouTube video of dodder vine locating and reaching for a tomato plant
Dodder management guide lines
“We show that exposing tomato plants to some level of caterpillar herbivory will increase resistance for future plants—it’s sort of like a plant vaccine,” says Sergio Rasmann, a biologist at the University of Lausanne in Switzerland.
Rasmann isn’t the only one seeing this effect. In a similar study, Ann Slaughter of the Universite de Neuchatel in Switzerland infected Arabidopsis thaliana plants with a benign strain of the bacteria Pseudomonas syringae (PstavrRpt2). The offspring were more resistant to disease than control groups, which were not infected in the first generation.
How does pest resistance get inherited? Researchers point to epigenetic mechanisms, which regulate gene expression and can be passed from one generation to the next without any changes to DNA sequences. The studies suggest known epigenetic factors like DNA methylation and histone modification mediate these effects, and are among the first to demonstrate siRNAs act as an epigenetic mechanism in plant defense responses.