Plant Lignin Found in Red Algae

first_imgTime to rewrite the textbooks again.  The story of plant evolution is wrong.  Lignin, a chemical that gives wood its stiffness, was thought to be unique to land plants.  Now it has been found in red algae, reported Science Daily, with the title, “Billion-year Revision Of Plant Evolution Timeline May Stem From Discovery Of Lignin In Seaweed.”  This story illustrates that anything is possible in evolutionary biology these days.    According to evolutionists, red algae emerged much earlier than land plants.  How are they going to explain a complex molecule, which is manufactured by a complex process, being found in a more “primitive” life form?  “Because red and green algae likely diverged more than a billion years ago, the discovery of lignin in red algae suggests that the basic machinery for producing lignin may have existed long before algae moved to land.”  But that just seems to restate the problem.  The alternative, though, is even harder to swallow: “Alternatively, algae and land plants may have evolved the identical compound independently, after they diverged.”    The independent evolution of an identical compound in unrelated lines is tantamount to a miracle.  Look what Mark Denny of Stanford said about this: “The pathways, enzymes and genes that go into making this stuff are pretty complicated, so to come up with all those separately would be really, really amazing,”says Denny.  “Anything is possible, but that would be one hell of a coincidence.”Paper View: Denny’s statement warranted a further look at the original paper in Current Biology.1  Sure enough, the only two options were evolutionary, and neither was unproblematic.  “The discovery of polymerized hydroxycinnamyl alcohols (lignin) within the cell walls of a red alga has major evolutionary implications,” they said in a tone of understatement.  Either the ability to synthesize lignin emerged in a single-celled ancestor (with no need for the sturdiness of plant stems), or it emerged by convergent evolution in unrelated lineages.  “Because monolignol synthesis is exceptionally complex, it seems unlikely that Calliarthron [the red alga] and terrestrial plants evolved monolignol biosynthesis and polymerization completely independently,” they confessed (see 05/30/2008, bullet 2).  Why, then, did the title of their paper say this “reveals convergent evolution of cell-wall architecture”?  Perhaps there is a way to get the best of both explanations.  “It seems more likely that relevant pathways, such as phenylpropanoid biosynthesis and polymerization by peroxidase-catalyzed oxidation, may be deeply conserved, having evolved prior to the divergence of red and green algae more than 1 billion years ago.”  If so, “we may expect to find conserved enzymatic pathways and, potentially, evidence of lignification among the multitude of evolutionary intermediates.”  The search is on.    Nevertheless, they did entertain the possibility that red algae and land plants converged on the highly-complex lignin pathways independently.  For support, they pointed to one other case of convergent evolution in lignin synthesis: “For example, angiosperms and the lycopod Selaginella synthesize S lignin via distinct and independently evolved cytochrome-P450-dependent monooxygenases, and production of S lignin in Calliarthron may reflect a third convergent pathway.”  This seems to beg the question that they evolved.  Perhaps two improbabilities are better than one, and three better than two.  Since nothing but evolution is allowed in the explanation, though, those are the choices.  Maybe imagining other uses for lignin in microbes will help:Lignins are thought to have evolved in the green algal lineage as adaptations to terrestrial habitats, facilitating hydraulic transport and contributing to the mechanical stability of upright stems.  However, contrary to the current paradigm, our data indicate that H, G, and S lignins exist within a red alga’s calcified cells that lack hydraulic vasculature and have little need for additional support.  We speculate that lignin biosynthetic pathways may have functioned in the common unicellular ancestor of red and green algae, protecting cells from microbial infection or UV radiation, and in Calliarthron, lignins may orient the fibrillar scaffolding that guides CaCO3 deposition.While we’re speculating, let’s imagine more with the long leash of evolutionary thinking.  There may have been other needs within brainless microbes that provided opportunities for evolutionary invention via “selective pressure.”The presence of G lignin within the secondary walls of peripheral genicular cells may represent convergent evolution of cellular architecture in response to mechanical stress, given that G lignins also concentrate within secondary walls of terrestrial plant fibers.  Selective pressures in the marine environment differ from those on land, but the wind-induced drag forces that presumably contributed to the evolution of wood in terrestrial plants are mirrored by flow-induced drag forces on aquatic algae.  On land, xylem lends mechanical support to erect stems, and in water, genicula provide mechanical support to Calliarthron fronds.  As articulated fronds bend back and forth under breaking waves, bending stresses are amplified within peripheral genicular tissue, which develops thick secondary walls, apparently to resist breakage…. We hypothesize that this putative 3- to 5-fold upregulation of lignin biosynthesis in peripheral genicular cells may be mechanically stimulated by bending stresses imposed by breaking waves.  Similar mechanical on/off switches for lignin accumulation have been noted in terrestrial systems: plants grown in microgravity synthesize less lignin, whereas plants grown in hypergravity synthesize more lignin.  The mechanical consequences of such minute quantities of lignin on genicular material properties may be negligible.  Nevertheless, that genicular tissue contains lignin and is also stronger, stiffer, and yet more extensible than other algal tissues is an intriguing coincidence, and lignin’s potential role in these properties is an area of active research.Their reasoning leaves out a key question.  Their evidence refers only to spots where lignin accumulates in response to mechanical stress.  How did it get there in the first place?  What does accumulation have to do with the origin of the lignin synthesis machinery?  They didn’t say.  The argument merely hints that an applied stress will somehow produce the goods.  Necessity is the mother of invention.    Having earlier admitted that lignin synthesis is “exceptionally complex,” it is perhaps surprising to hear them land on the side of convergent evolution in their concluding paragraph.  Their last sentence included overt teleological language:Convergent evolution of cell structure and development in Calliarthron genicula and terrestrial xylem may clarify lignin biosynthesis and lend insight into the early evolution of land plants.  It is striking that Calliarthron contains lignified cell walls but evolved from calcified ancestors that lacked water-conducting tracheids or vessels.  Vascular plants may have realized hydraulic transport by tapping into ancient biosynthetic pathways that initially evolved to fortify unicellular walls and were later adapted to provide biomechanical support.With funding from the National Science Foundation, Patrick Martone (co-author with Denny) is continuing work on this surprising discovery.  Science Daily ended, “Martone says the research team has started looking for billion-year-old lignin genes that might be shared among land plants and red algae, and has started exploring whether lignin exists in other aquatic algae and what role it plays in the evolution and function of aquatic plants.”1.  Martone, Estevez, Lu, Ruel, Denny, Somerville and Ralph, “Discovery of Lignin in Seaweed Reveals Convergent Evolution of Cell-Wall Architecture,” Current Biology, Volume 19, Issue 2, 27 January 2009, Pages 169-175, doi:10.1016/j.cub.2008.12.031.Darwinism is supposed to be this law-governed, enlightened, mechanistic, scientific theory that gives rational explanations for observed phenomena in nature.  Pray tell, what is the difference between their evolutionary explanation and that of a shaman?  We have just seen these scientists invoke spirits.  They called on the spirit of convergent evolution, the spirit of Tinker Bell, and the spirit of vascular plants tapping into ancient biosynthetic pathways that “initially evolved to fortify” cell walls of microbes.  These purpose-driven spirits produced lignin biosynthesis machinery on demand, just because of environmental stress.  Miraculous (see 03/25/2003).  “Anything is possible,” Denny said.  At least Christians have a sufficient Cause when they say, “With God, all things are possible.”    When you learn to look past the big words and identify the key passages in a scientific paper, it’s like taking your gaze off the Wizard of Oz act and pulling up the curtain where the charlatan is hiding.  A theory that says “anything can happen,” even coincidences that are “really, really amazing” can explain anything.  Is this enlightened?  Is this progressive?  Is this rational?  No matter what the observations, the Darwin Party has carte blanche to say “It evolved, because stuff happens” (09/15/2008).  To get really disgusted, read how the Astrobiology Magazine spun this finding in to a positive for evolution!  “The team’s finding provides a new perspective on the early evolution of lignified support tissues – such as wood – on land, since the seaweed tissues that are most stressed by waves crashing on shore appear to contain the most lignin, possibly contributing to mechanical support, says Martone.”  This is why we really need to end the one-party rule in science.  The Darwinists have done nothing to stop the rampant, blatant, out-of-control identity theft (05/02/2003) and credit fraud (08/24/2007) that is damaging the public trust (12/18/2002).(Visited 371 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img

Leave a Reply

Your email address will not be published. Required fields are marked *