麻豆淫院

A wild ginger has a clever trick up its sleeve to lure in pollinators. No, it's not a sweet fragrance that fills the air, but the foul stench of rotting flesh and dung. To attract carrion-loving flies and beetles, the flowers of the plant genus Asarum brew a malodorous chemical called dimethyl disulfide (DMDS) with the help of a disulfide synthase (DSS)鈥攁n enzyme derived from another enzyme, methanethiol oxidase (MTOX), found in both animals and plants.

A by researchers from Japan discovered that a few tweaks in a gene primarily responsible for detoxifying smelly compounds have independently evolved in three different plant lineages to produce unpleasant odors.

The same three amino acid changes, found in all the independently evolved DSS enzymes, enabled the transition from MTOX to DSS activity, according to the research published in Science.

A select few organisms are able to thrive in ecological niches that others cannot access. Their drive to survive is fueled by adaptive radiation, where species diversify by evolving a set of specialized or enhanced metabolic traits. Understanding how these novel traits arise, their evolution over time, and what limits their development is a key area of interest across various fields of modern biology.

Natural selection often favors repeated evolution of beneficial traits, thus opening up ways for scientists to study the changes using phylogenetic comparative methods鈥攕tatistical techniques that are used to analyze the history of organismal evolution and diversification.

An interesting trait to investigate is the ability of angiosperms or flowering plants to mimic the appearance and smell of carrion or dung to attract pollinators, a strategy that independently emerged in multiple plant lineages.

Previous studies have shown that floral oligosulfides, the strong foul-smelling sulfur-based compounds, come from the bacterial breakdown of sulfur-containing amino acids such as cysteine and methionine. While their role in attracting pollinators is well documented, not much is known about the genetic and physiological mechanisms that enable flowers to emit these volatile compounds.

To uncover the evolutionary pathways and genetic changes that facilitate this behavior, the researchers focused on Asarum, a group of plants that have acquired the trait for producing malodors repeatedly over a relatively short evolutionary timescale of less than 7 million years.

The researchers analyzed the volatile compounds produced by 53 Asarum species and eight varieties. To identify whether oligosulfides like DMDS come from the amino acid l-methionine or not, isotope-labeled feeding experiments were carried out where flowers were given l-methionine labeled with carbon-13.

They found that both the DMDS and the dimethyl trisulfide (DMTS) produced contained the carbon-13 label, confirming l-methionine as the source.

The researchers identified three major classes of selenium-binding protein (SBP) genes in Asarum.

By expressing these genes in E. coli, they found that one class, SBP1, encodes enzymes that convert methanethiol into DMDS. A correlation between the amount of DMDS emitted by the flowers and the expression levels of SBPs was also reported.

The study suggests that the widespread occurrence of DMDS emission in floral mimics may be due to the ease with which a highly conserved enzyme can be repurposed through just a few amino acid changes.

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