June 27, 2020 | David F. Coppedge

Plant Wonders Inspire Awe

From small herbs underfoot to towering giants, plants have what it takes to thrive in their habitats.

Biomechanical analyses and computer simulations reveal the Venus flytrap snapping mechanisms (Phys.org). After well over a century, scientists are still trying to figure out the Venus flytrap. This unique carnivorous plant can snap shut in just 100 milliseconds. It can tell the difference between a live bug and a dead leaf. And unless the bug touches one or more of the trigger hairs within 20 seconds, it will not close. How does it do these things without eyes, muscles, or a brain? The latest work comes from research at the Albert Ludwigs University of Freiburg, where a team found that

the trap of the carnivorous plant is under mechanical prestress. In addition, its three tissue layers of each lobe have to deform according to a special pattern.

Venus flytrap (Jason, Flickr)


How the giant sequoia protects itself
(University of Freiburg). From the small to the tall, the same university explored how giant sequoias (the most massive organisms on the planet) survive for hundreds or even thousands of years through all kinds of stresses from fire, drought, infestation, and even falling rocks.

Sequoia bark is composed of fibers in networks that give it a tough yet spongy character. (DFC)

The University of Freiburg team has shown that the bark fibers form a three-dimensional network with cavities. This network distributes energy acting on the bark across the entire tissue. The results of their study have been published in the “International Journal of Molecular Sciences.

The outer bark of the sequoia tree contains many fibers, which are organized in fiber bundles. These cross over each other and are also layered on top of each other, creating a three-dimensional netted structure. In between the fiber bundles are air-filled cavities. When a rock strikes the bark, these cavities are compressed. Compressing the hollow spaces and stretching the fiber network has the effect of distributing the energy evenly over the bark and protecting the inside of the tree with the sensitive cambium that forms wood and bark. The bark later returns almost completely to its original state. The cavities also insulate the tree so that it is resistant to the heat generated during wild fires.

Plants are marvelous chemists, as the gardenia’s DNA shows (University of Buffalo). Scientists at UB are amazed at the chemical wizardry plants can perform, yet they attribute it all to evolution! Reporter Charlotte Hsu doesn’t realize how incoherent she sounds.

  • The species’ newly sequenced genome highlights how evolutionary tinkering transforms plants into some of nature’s great chemical-makers.
  • The findings, published on June 18 in BMC Biology, highlight the power of an evolutionary process called tandem gene duplication, in which accidental copying of DNA gives organisms flexibility to expand the arsenal of genetic tools they have at their disposal. It’s just one way that plants can evolve new capabilities, but it’s a crucial one.
  • In a tandem duplication event, a single gene gets replicated by mistake during reproduction. Then, as a species evolves over time, the excess DNA is free to mutate and take on new functions.
  • “This is a case where we see the same underlying evolutionary mechanism generating these tandem duplicates to create two different biosynthetic pathways of interest in two plants,” Albert says. “We have coffee and gardenia, which evolved from a close common ancestor, and in one case tandem duplicates formed and went crazy in coffee to make caffeine. And in the other, they formed and went crazy in gardenia to make crocins.”
  • Crocin is found not just in gardenias, but also in the crocus plant, which produces saffron. These species didn’t inherit the ability to make crocin from a common ancestor: They evolved their arsenal of genes independently. The same goes for caffeine genes in coffee, tea and chocolate plants.
  • “Plants are playing games with multiple evolutions of interesting phytochemicals,” Albert says. “And, of course, all of these phytochemicals are useful to the plants, maybe in fighting against pathogens or serving as attractants to insects.”

But who is playing games here? What idea went crazy? Is it not the notion that blind, unguided processes came up with complex syntheses of useful molecules? Dr Victor Albert wants us to believe that multiple miracles of chance occurred in different species. How crazy is that? As for tandem duplication, try an experiment: print two copies of a work of art, and see which one gets better over time. Or duplicate your toolbox and shake them separately to see which one builds a better device. Albert is ascribing creative powers to chance. That’s nuts. If subspecies of related plants can synthesize new molecules, it’s because they were programmed to do so.

Notice that Dr Albert would like to learn from the plant how to do it. Surely he is not going to use blind chance.

The study identified the genes involved in making crocin and used them to create the compound in the lab. This work — which included deciphering the step-by-step process that gardenias use to synthesize crocin — lays the foundation for large-scale production of the chemical, which is thought to have medicinal properties as an antioxidant.

If he really believed his evolutionary story, he would take a plant that doesn’t have the gene, create a mutant with two copies of another gene, and irradiate the plant with UV or X-rays. Then he would sit back and watch if evolution can create the ability to synthesize crocin.

The diversity of vascular plants is tremendous, and now we know that different species communicate with coded messages, like email. (DFC)

Plant vesicles inspire methods to protect crops (Nature). To blow away the Darwin smell of the last article, let’s look at some amazing design features in plants. Here’s an update on the finding that plants have “email.” It was an astonishing thought when we first reported on the capability in 2001 (see update from 7 April 2017) that plants send coded messages throughout their “intranet” of vessels to cause responses at the receiver. Now, the concept has expanded to an “internet” where plants can communicate with other species. Now, too, scientists are also learning to read the language in the messages. Some of them are written in RNA — extracellular RNA, or exRNA. The article in Nature says, “Some studies have suggested that plants and fungi exchange RNA through extracellular vesicles.

Plant biologist Hailing Jin at the University of California, Riverside, is trying to revive the field to work out how plants send cellular messages. She has found evidence that plants do this, in part, to thwart their fungal enemies. She is now designing fungicides that are based on exRNA.

Moreover, the messages are sent in “envelopes” or vesicles called exosomes, similar to how digital email is packetized. Roger Innes at Indiana University has been working on this since 2013 when a colleague found evidence of exRNA traveling outside plant cells in vesicles. “It opened up whole new directions in plant science,” he remarks.

Innes, for his part, is looking for more evidence that exosomes are indeed involved in RNA signalling. Circular cross-sections can be seen near plant cells under a microscope, but Innes wants to confirm that these shapes are exosome spheres, and not just cylindrical tubes. To do this, his group is creating ultra-thin slices of plant cells and capturing an image of each slice with an electron microscope. It can then digitally recreate the 3D shape of the tiny structures assumed to be exosomes. He’s sure that plants do send out RNA signals, but he wants to definitively show the form of the structures that shuttle this genetic information. “We know it works,” Innes says. “The big question right now is how.”

This is cutting-edge research with a lot to learn. It may open up understanding of plant ecology, and perhaps lead to better methods of crop control, like spraying fields with RNA instead of pesticides.

Plants are a gift of God, the Creator of life. Let’s learn about them, use them, and enjoy them. Keep Darwin’s bad breath away; it makes plants wither and die, and hardens human hearts. The cure for a hard heart is gratitude and awe.

Who could design things as wonderful as plants? Give God the glory. (Photo by DFC)

 

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