Evidence of 250 Million Year Old Aeronautics in Kauri Seed

Evidence of 250 Million Year Old Aeronautics in Kauri Seed

California research identifies Kauri role 

KseedResearchers at the University of California, Berkeley have discovered evidence that the physics of helicopter wings was evolving in pineus trees 270-million-years-ago. Using winged seed from the oldest surviving pineus species, Agathis australis, the New Zealand kauri, showed how the whirling helicopter wings evolved from 270-million-year-old fossils of an earlier conifer.

Whirling, or helicoptering, keeps a seed aloft longer, increasing the chance that a gust of wind will carry a seed to a space where it can grow apart from its notoriously dominant parent.

“Winged seeds may have contributed to the success of these conifers,” said paleobotanist Cindy Looy, an assistant professor of integrative biology at UC Berkeley, a member of the Berkeley Initiative for Global Change Biology (BiGCB) and a curator with UC Berkeley’s Museum of Paleontology.

Today, however, all conifer species whose seeds whirl as they fall appear to have settled on only one type of design: asymmetrical and single-winged. Several different conifer lineages independently came upon this single-winged design after experimenting with helicoptering winged seeds over millions of years of evolution.

To convince herself that later conifers settled on the most efficient design for windborne seed dispersal, Looy and her colleagues built model seeds inspired by the variety of seed designs found in a unique collection of 270 million-year-old fossil seeds from Texas.

By dropping these model seeds and filming their descent with high-speed cameras, they demonstrated that whirling, single-winged seeds were the most effective at aerial dispersal. Symmetric, double-winged seeds often failed to initiate the descent-slowing spin, but even if they did, they remained airborne only half as long as the single-winged ones.

Moreover, the difference in flight performance of single-winged whirling seeds and asymmetrical or symmetrical double-winged ones increased with increased seed weight or in turbulent air.

Looy, former research assistant Robert Stevenson and former graduate student Dennis Evangelista, now at the University of North Carolina at Chapel Hill, will be published in the Spring 2015 issue of the journal Paleobiology.

Looy has been studying fossils of early conifer groups from deposits in Texas dating to the Permian Period, about 270 million years ago. She was struck by the fact that one of the conifer species produced a range of seed shapes, ranging from single-winged to asymmetrical and symmetrical double-winged seeds

This is unusual, she said, because the single-winged seeds have the clear advantage of enhanced dispersal efficiency, especially during the Permian when seed dispersal by animals was virtually absent. Even more unusual was the fact that different conifer species that independently evolved whirling, or autorotating, seeds ended up with only one optimal seed shape up in today’s conifer species. The same is true for other trees that developed similar seeds or fruits, such as the maple and ash.

The Permian conifer, which she and Stevenson formally described last year and named Manifera talaris, produced the oldest known autorotating conifer seeds roughly 40 million years before dinosaurs evolved.

“Rotating seeds in living conifers are generally asymmetrical and single-winged, so I wondered if the function of the double-winged seeds was very different,” she said. “Until you actually see them in action and compare them, you don’t have any proof.”

Paper wings and plastic seeds

Looy knew that people had tested the aerodynamics of single-winged, autorotating seeds, but no one had ever studied the other designs because they aren’t found today. Using special tissue paper for wings and plastic film for the heavy seed, she and her colleagues built models of the single-winged seeds of a living conifer that resembled those of the fossil conifer. The actual seeds of this tree, the New Zealand kauri (Agathis australis), were used to confirm that the fabricated models behaved like the real thing.

They then altered the design of the models to match the symmetric and asymmetric double-winged as well as the single-winged seeds common among the Texas fossils. The researchers dropped the seeds from a height of 3 meters (9 feet) and filmed their fall with a high-speed camera. This enabled them to observe the flight performance and measure a range of flight characteristics and aerodynamic properties of the various shapes. They enlisted half a dozen UC Berkeley undergraduates to help determine which type of winged seed works best for wind dispersal and to digitize the flight behavior of the seeds captured on camera.

They found that, in contrast to the single-winged seeds, the symmetric and asymmetric double-winged seeds did not spin as effectively; instead of a slow helicopter descent, they usually fluttered or just plummeted to the ground. But even when seeds with double-winged shapes managed to autorotate, the experiments demonstrated conclusively that single-winged seeds stayed airborne almost twice as long.

Early seed dispersal

Air- and waterborne seeds became more common between the late Carboniferous – 320 million years ago – and early Permian, which began about 300 million years ago. At the time, most plant life consisted of lycopods, ferns, horsetails and seed ferns, with a few of the first cone-bearing trees, like conifers and cycads, appearing.

“There were very different plants around at the time,” Looy said. “Several of these groups produced seeds, but they lacked most of the tricks we see today to spread them.”

Vertebrates, only a few of which were herbivores, were typically large and did not climb trees. The only flying animals were insects, and as far as we know they did not disperse seeds, Looy said.

“For a seed at that time, having wings was actually one of the few ways to spread widely,” she said.

The conifer fossils, which are from north-central Texas, date from a time when Texas was located near the equator, and North America was part of the massive continent of Pangea. Looy studied these fossils when she worked as a postdoctoral researcher at the Smithsonian Institution from 2004 to 2008, and was struck by the seed variety within a single species compared to today.

“In these conifers you can see steps from making winged seeds to making autorotating seeds. It seems that the Permian conifer Manifera first figured out how to produce a range of winged seed shapes -including the highly functional autorotating ones,” she said. “However, fossils of closely related end-Permian conifers suggest that it wasn’t until much later that they discovered how to not produce the less functional types. Around that time, we also see the first slightly succulent conifer seeds appearing in the fossil record, which are attractive to animals and potentially indicative of animal dispersal. Slowly the seeds start to diversify to all the different types we have nowadays.”

RNA Breakthrough Offers Hope in Kauri Dieback Fight

RNA Breakthrough Offers Hope in Kauri Dieback Fight

DISCOVERY MAY HELP KAURI

Pre-mRNA-1ysv-tubesResearchers at the University of California, Riverside have made a discovery that could prove important in the fight against PTA, the pathogen known as Kauri Dieback that is killing our great tree. The scientists identified a fundamental microbiological process that could be at the heart of the fungal nasty, Phytophthora taxis agathis that is the cause of the current Kauri Dieback epidemic.

Kauri was resistant to phytophthora, of which there are thousands of species, so the current attack on these trees has taken local scientists and foresters by surprise. However the discovery of the method phytophthora uses to suppress a plant’s immune system may help fight the dieback problem.

Phytophthora attacks plants through cytoplasm secreting mechanisms known as haustoria. Their secretions use a motif, the molecular structure of a substance called an effector that the plant identifies as friendly, to invade the plant’s basic intercellular functions at a molecular level. However, scientists have so far failed to identify how this happens once the infection is inside the plant.

Now it appears that the motif used by phytophthora, mostly that of an effector known as RxLR, engages directly with proteins in the plant know as interacting proteins. These are the means by which plants control their supply and utilisation of RNA, which they suppress as their main means of defence against viral activity.

It appears that RxLR closes down the suppression function of the interacting proteins, PSR1 and PSR2, by having a direct influence on another protein. This nuclear protein containing the aspartate-glutamate-alanine-histidine-box RNA helicase domain in the plant is known as PSR1-interacting protein 1 (PINP1), and it may hold the key to kauri survival. As it is required for the accumulation of small RNAs and to be important to miRNA and siRNA biogenesis and processing, it appears to be a critical part of phytophthora’s attack mechanism.

The full paper,
Qiao Y, Shi J, Zhai Y, Hou Y, and Ma W, : Phytophthora effector targets a novel component of small RNA pathway in plants to promote infection,
Was published in The Proceedings of the National Academy of Science, April 20 2015.

Minister Ignores Advice to Protect Kauri

Minister Ignores Advice to Protect Kauri

Simonbridges

Documents released today to Radio New Zealand show that Minister of Transport, Simon Bridges ignored advice from the Transport Agency that the Waipoua Forest bridge between the Darby and Joan kauri could not and “should not” be widened because of threats to the trees’ survival inherent in road works.

Tangata Whenua, te Roroa agree that the bridge should not be touched because of the trees, and Northland MP, Winston Peter has accused Bridges of incompetence.

The plan to widen the bridge was announced by Simon Bridges as part of the National Party’s by-election campaign in Northland.

Phosphorous acid for controlling Phytophthora taxon Agathis in kauri: glasshouse trials

I.J. Horner and E.G. Hough he New Zealand Institute for Plant & Food Research Limited, Hawke’s Bay Research Centre, Private Bag 1401, Havelock North, New Zealand Corresponding author: ian.horner@plantandfood.co.nz

Abstract Phytophthora taxon Agathis (PTA) is a serious problem in Auckland and Northland kauri forests. Phosphorous acid (phosphite) is a potential treatment for infected or threatened trees. In vitro tests on phosphite-amended agar showed that PTA was more sensitive to phosphite than other Phytophthora species commonly controlled by this chemical. Before progressing to forest trials, phosphite eficacy was tested on PTA-inoculated kauri seedlings in the glasshouse. Two-year-old kauri seedlings were inoculated with PTA applied directly to trunk wounds or by soil application. Phosphite was applied as a foliar spray, as a trunk injection or as a soil drench either 5 days before or 5 days after inoculation. All untreated control trees died, whether trunk- or soil-inoculated. With phosphite injection, survival was 100% following PTA soil inoculation and 67% following trunk inoculation. Foliar spray and soil drench-applied phosphite treatments were less effective than trunk injection, although some trees survived.

PM SAYS TREES ARE SAFE

PM SAYS TREES ARE SAFE

darbynjoan

Darby and Joan, the twin kauri alongside the road through the Waipoua Sanctuary, will not be felled to build a two lane bridge between them. This is the promise of Prime Minister, John Key given in Parliament last week, following concerns the Government’s Northland election promise to upgrade the bridge put the trees at risk.

When the Waipoua Sanctuary section of State Highway 12 was sealed twenty years ago special platforms were built across the roots of the two ancient trees to protect them from damage. At the time the roading solution was considered a significant environmental achievement.