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Researchers: Horizontal (lateral) gene transfer among grasses is widespread

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Remember the claim we noted last night that “horizontal gene transfer is considered exceptionally rare outside of bacteria”? Well, now:


● Lateral gene transfer (LGT) occurs in a broad range of prokaryotes and eukaryotes, occasionally promoting adaptation. LGT of functional nuclear genes has been reported among some plants, but systematic studies are needed to assess the frequency and facilitators of LGT.

● We scanned the genomes of a diverse set of 17 grass species that span more than 50 Ma of divergence and include major crops to identify grass to grass protein coding LGT.

● We identified LGTs in 13 species, with significant variation in the amount each received. Rhizomatous species acquired statistically more genes, probably because this growth habit boosts opportunities for transfer into the germline. In addition, the amount of LGT increases with phylogenetic relatedness, which might reflect genomic compatibility among close relatives facilitating successful transfers. However, genetic exchanges among highly divergent species indicates that transfers can occur across almost the entire family.

● Overall, we showed that LGT is a widespread phenomenon in grasses that has moved functional genes across the grass family into domesticated and wild species alike. Successful LGTs appear to increase with both opportunity and compatibility.

Samuel G. S. Hibdige, Pauline Raimondeau, Pascal-Antoine Christin and Luke T. DunningAnimal and Plant Sciences, University of Sheffield, Western Bank Sheffield S10 2TN, UK

So what becomes of detailed claims about the path that explicitly Darwinian (ancestor to descendant) evolution took if horizontal gene transfer is widespread? How do we know that Darwinian evolution was even involved?

The paper is open access.

See also: Giant corpse flower has lost most of its genes, grabbed some from its plant hosts. At Quanta: “Davis’ team estimated that at least 1.2% of the plant’s genes came from other species, particularly its hosts, past and present. That might not sound impressive, but this kind of horizontal gene transfer is considered exceptionally rare outside of bacteria. So even a single percent of genes arising this way raises eyebrows.” Researchers are still trying to figure out why the parasitic plant has such a huge genome. Commendably, they are NOT claiming it’s all just junk.


Horizontal gene transfer: Sorry, Darwin, it’s not your evolution any more

Polistra - I don't think that's what's happening. More likely, the transfer is through normal sexual reproduction. There has been a lot of artificial gene flow between cereals, done by humans, using pollen. I was once offered access to crosses between wheat and barley. Bob O'H
Only semi-related but relevant to Darwin’s analogy to animal husbandry. Does anyone know if there is more or less genetic variation today in the entire population of domestic dogs than there was in their wolf ancestors? paige
Makes sense. Rhizomes provide communication channels among plants in a field. A plant that is being chewed by a caterpillar can tell the others to emit appropriate poisons. Why not the HGT channel as well? polistra
So what becomes of detailed claims about the path that explicitly Darwinian (ancestor to descendant) evolution took if horizontal gene transfer is widespread?
I guess it only works for 99.96% of grass genomes. The largest estimate in the paper is a move of 4 per 10k genes (see fig. 1), so although it's widespread in the sense that all the grasses do it, it's not common. Bob O'H

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