February 10, 2020 | Margaret Helder

Bad News for Plant Origins

The Riddle of the Reds (Seaweeds, that is)

by Margaret Helder, PhD

Anybody who has been to the seashore has probably had the opportunity of collecting shells and seaweeds. You can’t miss the long, flexible, almost rubbery kelps and other brown algae which litter the shore. These typically grow on the rocks which are pounded by the incoming tides and storms. More delicate than the browns are the dainty red algae. Some in the shallower areas are almost black. Many species of red algae grow on other algae like other reds or browns. At the low end of the intertidal region are delicate seaweeds that have a more pinkish color. Some of these are remarkably beautiful, with lace-like branching. With their red pigments, these algae can grow in the shade of the browns and even much deeper, since they can react to blue and green wavelengths which penetrate much farther down in the water.

The Unique, Beautiful Red Algae

The beautiful ‘reds’ (red algae) exhibit great variety of forms, from flat sheets (like Nori or Porphyra which one eats with sushi), broadly branching dulse (Rhodomenia or Palmaria palmata consumed by people from the northeast Atlantic coast) and more finely divided branching Chondrus crispus or ‘Irish moss’ which provides agar for human food and microbial cultures. Besides this variety, the red algae have some unusual distinctives. They have absolutely no swimming cells—not even sperm—and their sexual reproductive structures are highly unusual, similar only to some fungi in a group called Ascomycetes. These fungi include truffles, morels (also tasty), black mold (Aspergillus) and green and blue molds of Penicillium (found on citrus and other fruits and the source of penicillin). The pigments of the reds are somewhat similar to those of the blue-green algae (cyanobacteria). They possess other chemical products that are reminiscent of the blue-greens, but not of other algae.

Because of their lack of any swimming (flagellated) cells and their unusual sexual structures, red algae are strikingly different from other algae. Scientists for generations have wondered what might be the evolutionary ancestors of these eukaryotic organisms. [Eukaryotes are much more complex than bacteria (prokaryotes) in that they possess a nucleus and other organelles.] Evolutionists, of course, refuse to consider ideas that contradict universal common ancestry, such as separate creation of different types. The main trouble for these evolutionists is the difficulty of proposing any kind of relationship between red algae and other organisms. Elisabeth Gantt, one specialist commenting on this topic, said in 1979: “The greater the lack of pertinent information, the greater the speculations seem to be.”(1)

Now, evolutionists strive to bridge the large gap between red algae and photosynthesizing eukaryotes. In their 2019 paper in Nature entitled “Non-photosynthetic predators are sister to red algae,”(2) Gawryluk et al. understand the challenge before them. They confide that the characteristics of said predators “are nearly opposite of those that define red algae.” On what basis, then, do they propose a sister relationship to the red algae? (A sister relationship would imply both had a common ancestor.) Somebody was impressed enough with their scenario that the prestigious journal Nature printed it.

Seeking the Origin of Photosynthesis in Eukaryotes

The objective of their 2019 study was to find a mechanism to provide eukaryotic cells with the wherewithal to photosynthesize. Photosynthesis, however, is a highly complicated process which biologists still don’t entirely understand. Seeking to find a source for this talent, biologists have proposed the blue-green algae (cyanobacteria) as a suitable candidate. The blue-greens are prokaryotic: i.e., lacking a nucleus or other organelles. But they do have chlorophyll a, like all other algae and land plants. Blue-greens also have some accessory pigments called c-phycocyanins (blue) that pass light energy from a broader spectrum of wavelengths to chlorophyll a which drives photosynthesis. Red algae also have similar accessory pigments, called r-phycoerythrins, which are red. Thus, the evolutionists think they have some clues for a way to get a photosynthesizing body into an ancestor of the red algae.

The proposed evolutionary story now takes shape. For cells to obtain photosynthetic capabilities through an evolutionary process, the best scenario would be to find some ‘swimming predator’ that could engulf or consume cyanobacteria. This is the rationale for the recent paper in Nature. But one can’t just pick any old protozoan (single celled predator). The interest in this particular recently-discovered protozoan, named Rhodelphis, comes from comparing characteristics of many proteins in this single cell with those from 153 other major taxa. Some computer analyses clustered Rhodelphis closer to red algae, meaning they had more compounds that were similar to the reds than to other organisms. Nevertheless, why would evolutionists consider that a single-celled, non-pigmented flagellated organism might be at all related to the complex red algae?

Endosymbiosis: The Plot Thickens

This brings us to the idea of “endosymbiosis,” a process that is presented as fact in most biology textbooks. Students usually learn that a prokaryotic cell engulfed another prokaryotic cell and that the consumed cell became reduced over time to function as the host cell’s mitochondrion or powerhouse, burning organic compounds to produce energy. For plants, however, a different story of endosymbiosis is told. Specialist John Archibald declared in 2009: “Unlike the origin of mitochondria, the details of which are still debated, there is no longer any doubt that plastids are derived from once free-living cyanobacteria and that the host cell was a full-blown eukaryote with a nucleus, cytoskeleton and mitochondrion.” (3) A plastid is synonymous with the familiar chloroplast. But chloroplasts are in green algae and land plants and possess chlorophyll b as well as chlorophyll a. All other photosynthetic organelles are called plastids because they have different accessory pigments as well as chlorophyll a and they may appear red, golden or brown. Explaining where all these plastids came from is the focus of endosymbiotic theory.

The currently-favored scenario of an endosymbiotic acquisition of a plastid or chloroplast is complicated. It not only involves the idea of a mobile predator engulfing a photosynthetic cyanobacterium, but for the almost wholesale transfer of genes from the engulfed cell into the host cell’s nucleus. Why would that happen and how did it occur? The result is a drastic increase in the difficulty of carrying out cellular metabolism.

The nuclear genome encodes most organellar proteins, although certain organelles, such as mitochondria and chloroplasts, contain some of their own genetic information. Coordination between the organellar genome and the nuclear genome is therefore required to ensure correct DNA content, DNA replication and protein translation.” (4)

There are many complications that arise from the synthesizing of proteins in the cytoplasm for later transport into an organelle. Noted biologist Christian de Duve pointed out in 1996,

Today mitochondria, plastids and peroxisomes acquire proteins from the surrounding cytoplasm with the aid of complex transport structures in the boundary membranes. … The transport apparatus then allows the appropriate molecules to travel through the membrane with the help of energy and of specialized proteins (aptly called chaperones). (5)

In the case of the mitochondrion we find, for example, that “Eucaryotic cytochrome c is localized and functions in the mitochondrion, yet the gene for cytochrome c resides in the nucleus.” (6)

Similarly, with the chloroplast (or plastid), the enzyme Rubisco catalyzes the first step in photosynthesis and is responsible for almost all carbon fixation on Earth (22 June 2006). But parts of this molecule are synthesized in the cytoplasm (controlled by nuclear genes), and the larger part is synthesized in the organelle. The two have to be put together once the smaller one has passed through the organelle membrane. (7) Another scientist remarked: “The plastid is a crucial organelle in plant cells…… However most plastid proteins (over 90%) are encoded by the nuclear genome and are imported into plastids from the cytosol post-translationally.” (8)

The 2019 paper by Gawryluk et al. is the latest attempt to provide convincing evidence that such an endosymbiotic event might have happened, resulting in the first photosynthetic algae. Two things would make their argument more convincing: (a) a plastid in the ‘predator’ (or at least evidence that there once was one there), and (b) flagella in the red algae (or at least evidence that they once had them for swimming). Do you suppose the scientists actually found such evidence?

Searching for the Flagellum

We have already noted that red algae never exhibit flagella. However, there is another structure that evolutionists can look for. There is an internal structure called a centriole that is found in cells with flagella. It is from this structure that the elaborate component parts of flagella emerge from a cell. Do red algae exhibit centrioles? In 1967, influential botanists Richard Klein and Arthur Cronquist declared:

The presence or absence of typical centrioles in the red algae, which have no flagella, is therefore a matter of considerable theoretical interest. If a typical centriole is present, then the red algae either have a flagellated ancestry, or they have the evolutionary anlage [capacity] from which flagella could be developed. If centrioles are absent, then presumably they do not have a flagellated ancestry, and neither do they have any structure from which flagella might be expected to arise. (9)

Another expert, Gordon Leedale, pointed out in 1970 concerning red algae:

No centrioles have yet been seen, and it is worth emphasizing that demonstration of centrioles in any red algae will have profound phylogenetic implications, since it would indicate that the absence of flagella in at least some of the Rhodophyceae is a derived [later] and not a primitive condition. (10)

Yet another specialist, Richard Searles, in 1980 concurred:

Rhodophyta [red algae] is the only division of eukaryotic algae in which flagella are never formed…. Electron microscopists have looked for evidence of vestigial flagella in spermatia [male sex cells], but the evidence suggests that red algae have never had the capability of producing flagella.” (11)

Now, in 2019 Gawryluk et al. admit that the red algae “lack cytoskeletal structures that are associated with motility, flagella and centrioles.” They further elaborate that “Notably, genes that encode flagellar proteins are absent from red algae.” (Nature 572 p. 240) As per the remarks of the earlier experts, the evidence indicates that red algae never had flagella. But Gawryluk et al. refuse to concede this. They speculate that the engulfing host cell must have suffered “marked gene loss” of hundreds of genes early in its history.

Photos by David Coppedge

Searching for the Plastid

Since the evidence does not support the idea that an ancestral red alga ever had flagella or could swim, what about the idea of a plastid in a supposed swimming ancestor? The 2019 paper insists that the capacity to engulf other objects “must have existed for the archaeplastid [red] ancestor to take up the plastid, and must have persisted at least until the protoplastid became a reliable source of both energy and nutrients” (p. 240, italics mine). So does this modern swimming predator ‘relative’ contain a plastid? Apparently not: “Plastids were not observed” (p. 240). Where is any evidence that this swimming predator ever contained a plastid? The search for such evidence is just beginning. Since “no plastids were observed using microscopy” (p. 241), they instead looked for genes that possibly were left over from a time when a plastid might have been present.

There is another complication to the idea that a predator engulfed a photosynthetic cell which later degenerated into a plastid. As John Archibald points out, this must have involved the transfer of possibly 1000 genes involved in photosynthesis from the plastid into the nucleus. This would leave only about 200 genes still inside the DNA remnant in the plastid. Not only that, but most of the proteins needed by the plastid are first formed outside the plastid and then transported through membranes into the plastid by means of a dedicated protein import apparatus. This requires numerous special proteins to work with the hundreds of compounds that need to enter the plastid (Current Biology p. R81).  As John Archibald further remarked:

It is not enough to simply transfer endosymbiont genes to the secondary [or primary] host nuclear genome. Each of the many hundreds of transferred genes must ‘acquire’ a coding sequence sufficient to produce a signal peptide that can be recognized by the nascent protein import apparatus. This gene-transfer/protein re-import process represents a potentially formidable barrier…. (Current Biology p. R84)

No one knows whether these processes could ever happen. The probability of finding so many precisely shaped new proteins to assist in transport would have been incredibly small.

Back to our 2019 examination of the swimming predator: the indications that it ever possessed a plastid are not encouraging. The scientists admit “Consistent with their lack of pigmentation, Rhodelphis encode almost no proteins that are involved in photosynthesis” (p. 242). Thus “we found no evidence that supports the existence of a plastid genome. No plastid DNA is present in the genomic datasets of R. limneticus” (p. 243). When they looked at the nucleus for genes related to plastids, they found “Similarly no nucleus-encoded components of plastid genome replication, gene expression or translational systems were identified in any Rhodelphis dataset” (p. 243). They thus concluded that “We interpret these observations as strong evidence for the complete loss of plastid DNA in Rhodelphis.” Obviously, they are assuming that a plastid was initially present despite the fact that they do not find one now. In contrast to this, they note that the red algal plastid is very gene rich, so there would have been a lot of genes to lose.

The Persistence of Belief

One might suppose this study would definitively eliminate this swimming predator from consideration as a possible ancestor to red algae, but it doesn’t. In evolutionary scenarios, imagination rules. The article in Nature even illustrates the cell of Rhodelphis with a “relic plastid” drawn inside it. This is based on the discovery of some compounds in the cell which are coded for in the nucleus and which could be connected with transport of compounds into a plastid, if there were one. These compounds could alternatively (and probably do) have other functions in the living protozoan. Moreover, the coding for these compounds is in the wrong location in the protozoan in that they are in the nucleus, but in the red algae these are coded for in the plastid (p. 243).

It is obvious that the case for an ancestral connection of this swimming single-celled predator to red algae definitely does not work. But evolutionists do not have much choice. They want to explain the appearance of photosynthesis in cells with a nucleus, and to do this they need a swimming predator to engulf a cell that already has the photosynthetic capacity. Without such an endosymbiotic event, evolutionists are stuck imagining that the capacity to photosynthesize occurred several times in various kinds of algae. This is so spectacularly unlikely that they have to be content to put up with the problems of endosymbiotic explanations. The scientists thought that Rhodelphis was promising, but it wasn’t. After generations of speculation, the experts still have no reasonable evolutionary suggestions for the origin of red seaweeds. Maybe they should consider that these did not evolve, but were designed.

References

  1. Elisabeth Gantt. 1979. Phycobiliproteins of Cryptophyceae. In M. Levandowsky and S. H. Hutner (Editors). Biochemistry and Physiology of Protozoa, 2nd edition, volume 1, ch. 5 pp. 121-137. The quote is from p. 134.
  2. Ryan M. R. Gawryluk, Denis V. Tikhonenkov, Elisabeth Hehenberger, Filip Husnik, Alexander P. Mylnikov and Patrick J. Keeling. 2019. Non-photosynthetic predators are sister to red algae. Nature 572 #7768 pp. 240-243. Quote is from page 240.
  3. John M. Archibald. 2009. The Puzzle of Plastid Evolution. Current Biology 19 pp. R81-R88. January 27. Quote is from page R81.
  4. Elena Ziviani and Luca Scorrano. 2016. The organelle replication connection. Nature 538 # 7625 pp. 326-327. Quote is from p. 326.
  5. Christian de Duve. 1996. The Birth of Complex Cells. Scientific American 274 #4 pp. 50-57. Quote is from p. 57.
  6. Rudolf A. Raff and Henry R. Maher. 1972. The non-symbiotic Origin of Mitochondria. Science 177 pp. 575-582 August 18. Quote is from p. 577.
  7. Lawrence Bogorad. 1975. Evolution of Organelles and Eukaryotic Genomes. Science 188 pp. 891-898 May 30. Quote is from p. 895.
  8. Dong Wook Lee, Sumin Lee, Young Jun Oh and Inhwan Hwang. 2009. Multiple Sequence Motifs in the Rubisco Small Subunit Transit Peptide Independently Contribute to Toc159-Dependent Import Proteins into Chloroplasts. Plant Physiology 151 #1 pp. 129-141. Quote is from p. 129.
  9. Richard M. Klein and Arthur Cronquist. 1967. A Consideration of the Evolutionary and Taxonomic Significance of Some Biochemical, Micromorphological, and Physiology Characters in Thallophytes. The Quarterly Review of Biology 42 #2 pp. 105-296. Quote is from p. 225.
  10. Gordeon F. Leedale. 1970. Phylogenetic Aspects of Nuclear Cytology in the Algae. New York Academy of Sciences, Annals 175 pp. 429-453. Quote is from p. 434.
  11. Richard B. Searles. 1980. The Strategy of the Red Algal Life History. The American Naturalist 115 #1 pp. 113-120. Quote is from p. 115.

Margaret Helder completed her education with a Ph.D. in Botany from Western University in London, Ontario (Canada). She was hired as Assistant Professor in Biosciences at Brock University in St. Catharines, Ontario. Coming to Alberta in 1977, Dr Helder was an expert witness for the State of Arkansas, December 1981, during the creation/evolution ‘balanced treatment’ trial. She served as member of the editorial board of Occasional Papers of the Baraminology Study Group in 2001. She also lectured once or twice a year (upon invitation) in scheduled classes at University of Alberta (St. Joseph’s College) from 1998-2012. Her technical publications include articles in the Canadian Journal of Botany, chapter 19 in Recent Advances in Aquatic Mycology (E. B. Gareth Jones. Editor. 1976), and most recently she authored No Christian Silence on Science (2016) which promotes critical evaluation of scientific claims. She is married to John Helder and they have six adult children.

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