Metabolic

Plants recycle specialized metabolic products to provide nutrients for primary metabolism

In fact, measurements of sulfur concentration showed that the seedlings had accumulated more sulfur than plants that had grown with a similar amount of sulfate. This led the team to suspect that the plants were also using other sulfur atoms (i.e., non-sulfate sulfur atoms) from the glucosinolate.

To investigate this, they made glucosinolates, in which the sulfur atom, which forms a key bond in the molecule, was a heavier isotope to be able to track through later metabolic processes. The team found that the labeled sulfur accounted for 28-42% of the various sulfur-containing amino acids in the seedlings, clearly demonstrating the breakdown of the supplied glucosinolate and its re-incorporation into primary metabolism.

“I was very excited to see that,” says Ryosuke Sugiyama, the study’s lead author. “Since the potential role of glucosinolate as a sulfur reservoir was discussed in terms of the sulfate group, we were surprised that the other common sulfur atom is also available as a source. This supported the existence of a systematic degradation pathway in plants. “

“Although the potential recycling of secondary metabolites has been discussed for decades, there has been no direct evidence of its physiological benefit,” adds Sugiyama. “Our results show that an important secondary metabolite is recycled by plants and can thus serve as a nutrient reservoir for the primary metabolism.”

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