Traditions during the holiday season, which stretch back hundreds of years before, have associated wintertime romance with ornamental sprigs of mistletoe.
The way that the rounded evergreen leaves of this plant, as well as the white berries, embrace the trees' branches tightly on which it is growing, perhaps, inspired that connection.
The fact about this botanic intimacy, according to QuantaMagazine "is less romantic" and that Mistletoe is a kind of parasite.
Its leaves yield sugars by photosynthesis rather than roots, and its structures pierce the host tree's essential tissues to suck out water and nutrients. As such, its relationship with the host could not be considered romantic or even platonic.
Also, such interdependence is going even deeper, and researchers are just beginning to realize the manners in which mistletoes are unique at the "molecular level because of it."
Role of 'Mitochondria'
All multicellular organisms' cells depend on the organelles, also known as "mitochondria" to make their biochemical fuel. All multicellular organisms except mistletoes, that is.
Mitochondria don't just produce little if any of the said fuel, but they have also lost many of the genes required to make it.
In a couple of years, since botanists found this anomaly, scientists all over the world have attempted with no more than limited success to find out how mistletoes are pulling off this trick.
Mistletoe Mitochondria
The first suggestion that mistletoes were really "sui generis" was presented by Elizabeth Skippington at the International Conference for Plant Mitochondrial Biology in Wrocław, Poland, in 2015.
Skippington, also a former postdoctoral fellow in the laboratory of Jeffrey Palmer at Indiana University, astounded the small scientific followers with evidence published later in the Proceedings of the National Academy of Sciences that Viscum scurruloideum, a mistletoe species, had a tremendously tiny mitochondrial genome and missed out key proteins believed to be needed for respiration, the chemical trail enabling mitochondria to produce adenosine triphosphate (ATP), the molecular fuel of the cells.
According to plant biochemist Jennifer Senkler, at Germany-based Leibniz University, in the next break, "everybody was chatting excitedly about this," and guessing how this could work.
The study authors wondered if probably, Skippington missed the genes since they had turned out to be unrecognizable, or if there was some mistake in her approach.
Or probably, genes had been transmitted into the nuclear genome. That's something that can occur with mitochondrial genes; in any case, the enormous genomes of the milestones have thus, far hindered whole-genome sequencing.
In conclusion, all research teams came out with a common conclusion that, Mistletoe mitochondria do not perform the same ATP-generating process as all the other plants' mitochondria, fungi, and animals.
The genes Skippington referred to are really gone and not mutated or relocated. And, as yet, nobody knows about the manner mistletoes are surviving without them.
Missing in Mistletoes
In all other multicellular life investigated at present, and in the majority of single-celled eukaryotes, for that matter, mitochondria yield ATP in a process comprising multiple steps.
Sweden-based Stockholm University botanist Gitte Petersen said each step is performed by a distinct suite of proteins, complexes I-V. "And one of these," the botanist added, the very first complex, is "totally missing in mistletoes."
Petersen, who trained as a plant systematist, initially thought that probably, this lack of complexity might be common.
However, when she, together with her colleagues, examined nine other parasitic plant groups, the rest were found to be normal. Something special apparently took place in the mistletoes alone.
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