First Flower Seeds from Dino Era Discovered
Various fruits and seeds of Early Cretaceous flowering plants, reconstructed from synchrotron radiation X-ray tomographic microscopy (SRXTM) scans.
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Else Marie Friis
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Plants: From Algae to Trees in 1 Billion Years
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Unlike animals, who began their evolutionary journey in the water, all terrestrial plants in existence today may have been on land all along, explains a new study. While biologists agree that the evolutionary tree for plants begins with green algae, a team of Danish scientists theorize that the algae from which all plants derive had been lounging on land for hundreds of millions of years rather than floating around in the oceans before drifting inland. A plant's cell wall is an important adaptation to living on land because it provides support for the plant to withstand the force of gravity, which wouldn't have the same effect in water. "We realized that algae have a cell wall that's similarly complex to terrestrial plant cell walls, which seemed peculiar because ancient algae were supposedly growing in water," co-author Jesper Harholt of Carlsberg Laboratory said in a statement. After analyzing the genetic data of a terrestrial species of green algae, the researchers found a number of genes linked to light tolerance and drought tolerance -- not exactly concerns of an aquatic organism -- that are shared with terrestrial plants. The findings of this study, published in Trends in Plant Science , reimagine a major milestone in the evolutionary trajectory of plant life. Although we tend to focus on animal evolution, specifically our own ancestral lineage, the plant kingdom has a rich natural history all its own. Fleeting Flowers and Late Bloomers: Photos
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PhysOrg/Wikimedia Commons
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U.S. Department of Agriculture
View Caption + #5: Elkinsia polymorpha
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Frank Mannolini/New York State Museum
View Caption + #7: Amborella trichopoda
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Thomas J. Lemieux, University of Colorado at Boulder
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PNAS and University of Göttingen/Alexander Schmidt
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Beginning around 11,400 BCE, during the Epipalaeolithic era, humans began taking over for Mother Nature, when our ancient ancestors started selecting plants for certain traits, such as sweetness in fruit, resilience to drought, or simply abundance. The earliest known crops planted by humans weren't cereals, like wheat, rye or barley, but rather fig trees. Archaeologists in Israel discovered a dwelling near the ancient city of Jericho that contained mutant figs, a rare kind of tree that only reproduces through human intervention by taking a cutting and planting it, NPR reported in 2006 . Flash forward to the 20th century and humans are beginning to manipulate the genes of plants directly rather than just selecting plants based on output. In 1983, a tobacco plant resistant to an antiobitic was the first transgenic, or genetically modified, crop ever produced. A decade later, genetically modified tomatoes hit store shelves in the United States, the first commercially available GM crop. Video: Can We Grow Plants on Mars?
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The world may never know if dinosaurs stopped to smell the flowers, but scientists have uncovered a few more clues about the ancient blossoms that grew alongside ankylosaurs and iguanadons. Recently, researchers discovered tiny Cretaceous flower seeds dating back 110 million to 125 million years, the oldest-known seeds of flowering plants. These puny pips offer a glimpse into the biology powering the ancient predecessors of all modern flowers.
The seeds are miniscule — the largest was no more than 0.1 inch (2.5 millimeters) in diameter — and unusually well-preserved, in such good condition that their internal cell structures were still visible. For the first time, scientists were able to detect seed embryos, the part of the seed where a new plant grows and emerges, and food storage tissues surrounding them. These structures offered a rare glimpse into how the Cretaceous seeds grew, and how they compare with plants alive today.
Else Marie Friis, lead author of the study and professor emerita at the Swedish Museum of Natural History, has analyzed some of these fossil remains of angiosperms — flowering plants — preserved in soils in Portugal and North America. She and her colleagues used a relatively new visualization technique — synchrotron radiation X-ray tomographic microscopy (SRXTM), which allowed them to explore the delicate fossils without damaging or destroying them. They imaged 250 seeds spanning 75 different species (some were also different genera), revealing the embryos and nutrient structures inside the seeds in exquisite detail. [ Photos: Ancient Flowering Plant May Have Lived with Dinosaurs]
Would it surprise you that the fruit in all-American apple pie isn't American at all? It originates from parts of Asia! The same goes for many fruits and vegetables we eat.
Around half of the fossil seeds they examined contained preserved cell structures within their seed coats, and about 50 seeds held partial or complete embryos. Once they had 2D images of the embryos, they used software to model the embryos’ shapes in 3D, finding that their size and shape varied between seeds. In some cases, the embryos resembled those in modern plants believed to be distant relatives of the Cretaceous angiosperms.
“These observations give us new insights into the early part of the life cycle of early angiosperms, which is important for understanding the ecology of flowering plants during the emergence and dramatic radiation through the early Cretaceous,” Friis said in a video statement.
During the Cretaceous period, angiosperms evolved and diversified rapidly. Many new insect species, which also appeared during the Cretaceous, may have played a part in how quickly flowering plants took hold and thrived in the ancient landscape.
Prior evidence from living and fossil plants has suggested that the earliest angiosperms grew close to the ground and took advantage of disrupted environments, and that they moved rapidly through growth stages. All of the seeds analyzed in the study were preserved during a dormant stage in their life cycle, the authors reported. The embryos were so tiny — less than one-fourth of a millimeter — that they would need to grow more inside the seed before they could germinate.
“Our discoveries support hypotheses based on extant plants that small embryos and seed dormancy are basic for flowering plantsas a whole,” Friis said. A dormant period for seeds meant that they could “wait out” a harsh environment and postpone growth until conditions were more favorable, a survival strategy practiced by many flowering plants today.
The findings were published online Dec. 16 in the journal Nature.
Original article on Live Science
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