White flower (Trifolium repens) is a tenacious plant that can grow in all climates and can be seen in almost all places. According to an article in Venchas, it is used as a basic ingredient in medieval times for broths to combat witchcraft and is still widely used in the production of Clover Honey.
However, they also release toxic cyanide as a defense mechanism called cyanogenesis. Biologists at Washington University in St. Louis recently published in their study, titled "Dual-Species Origin of an Adaptive Chemical Defense Polymorphism" published in New Phytologist, the genetic backstory of white clover's chemical defense mechanism.
Origin of White Clover's Chemical Defense Mechanism
According to Phys.org, white clover releases toxic cyanide when its leaf tissues are damaged to deter insect pests. Scientists claim that the plant developed this anti-herbivory superpower due to the hybridization of its ancestors.
Biology professor and lead author Kenneth M. Olsen said that their study showed that genes required for cyanogenesis in white clover come from one parental species and some come from the other.
"Whereas the two parental species have very narrow ecological niches-one grows only along Atlantic coastal cliffs in western Europe, the other only in alpine habitats of central Europe-white clover's ecological success can be attributed at least in part to cyanogenesis," he said in the university's news release.
Olsen and his colleagues integrated high-resolution genetic maps with genome sequence analyses in their study and found that each of the ancestors of white clover contributed to one of the two chemical compounds that are necessary for cyanogenesis.
Hybridization in White Clover Resulted in Potent Advantage
A large number of plant species today originated from hybridization. An article in the Journal of Physical Organic Chemistry showed that orbital hybridization is an electronic factor for unraveling many structural and reactivity puzzles during hybridization, which is an important process for plant speciation and diversification as two existing species cross with each other to form a new species.
Phys.org further reported that sometimes, the new species that formed could retain complete genomes of both parental species in a phenomenon called allopolyploid speciation because they contain all of the genetic material from both parents. A paper in Nature reported that this mechanism happens when different sets of chromosomes merge during hybridization.
The new species could rapidly evolve in all sorts of new adaptations which will allow them to thrive in different environments. Surprisingly, white clover's chemical defense system appears to be one of the very few examples of hybridization that resulted in a potent advantage.
Olsen added that there are very few cases where a new adaptation has been exhibited to have evolved by the allopolyploid speciation although it was previously thought that it is very prevalent and important in plant evolution. He emphasized that this was their basic reason for conducting the study.
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