Rare Plant Cancers 'Shatter' Chromosomes

Cancer is a very unique kind of disease. Rare in plants to begin with, experts had long thought that animals were more susceptible to often-fatal cancer conditions because they exclusively experience chromothripsis, commonly called "chromosome shattering." Now, experts have found the first evidence of this phenomenon in plants - a revelation with some intriguing implications.

That's at least according to a study recently published in the journal eLife, which details how lab samples of rockcress Arabidopsis - a small and flowering relative of cabbage and mustard - can undergo chromothripsis under very specific circumstances.

Rockcress is a famous subject of study, not because the plant itself is special, but because of the very opposite - it is simple. With a small genome of approximately 135 megabase pairs, Arabidopsis thaliana became the first plant to have its entire genetic makeup sequenced. Today, there is an extensive catalogue of all plants' variants and their genomes.

Having such a reliable model is what allowed Ek Han Tan, a researcher at the University of California, Davis, and the first author of the eLife paper, to determine that when a weakened variant of the cress is crossed with a normal version, the resulting embryos sport shattered chromosomes.

According to the researcher and his colleagues, traditional chromothripsis occurs when the centromeres - tiny fibers that hold chromosomes together (sister chromatids) - snap. Then, like a shaken puzzle, these chromatids scramble and randomly reassemble, creating severally flawed genetic information.

Sometimes this shattering shake-up results in small miracles. Just this year, it was revealed that an exceptionally rare immunodeficiency syndrome known as WHIM was completely erased in the genome of one patient after a drastic instance of chromothripsis occurred in the woman's spine.

However, the phenomenon usually just wreaks havoc on an organism, disrupting the flow of everyday cell life - a calling card of cancer.

Han Tan explained in a recent release that now that it's understood how this disastrous process can be triggered, it could be applied in plant breeding as a way to create new genomes - similar to GMO design. This would arguably be more natural than most current lab-side plant design, but it remains to be seen how exactly experts will guide the chromosome reassembling process.

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