Natures wonders: veus flytrap evolution studies (Introduction)

by David Turell @, Friday, May 13, 2016, 18:38 (1381 days ago) @ David Turell

How the flytrap may have developed its digestive enzymes is the subject of this study:

"In a study published online today in Genome Research, researchers characterized gene expression, protein secretion, and ultrastructural changes during stimulation of Venus flytraps and discover that common plant defense systems, which typically protect plants from being eaten, are also used by Venus flytraps for insect feeding.


"Unstimulated traps have gene expression patterns that largely resemble that of a leaf base, supporting the common assumption that traps are modified leaves. However, the glands inside the trap, which promote insect digestion, more closely resemble the expression pattern of roots, a tissue heavily involved in nutrient uptake.

"The researchers found that insect-stimulated traps upregulated enzymes involved in digesting prey and also transporters for nutrient uptake. Tracking the expression patterns of several hydrolases, the researchers determined that hydrolase expression was induced within 1-2 hours of touch stimulation, and a second stimulation event (mechanical or chemical) further amplified expression of chitinase, an enzyme that digests chitin in insect exoskeletons.

"'Contact with chitin normally means danger for a plant -- that insects will eat the plant," corresponding author Rainer Hedrich from the University of Würzburg said. Comparing the global gene expression changes during insect capture and digestion to the stress response of the model organism, Arabidopsis, the researchers found several commonalities. Jasmonic acid (JA), which is produced by non-carnivorous plants when they are wounded by herbivores, is upregulated in insect-stimulated traps. "In the Venus flytrap, these defensive processes have been reprogrammed during evolution. The plant now uses them to eat insects," Hedrich said.

"Unstimulated and stimulated traps both express receptor-like-kinases (RLKs), which are used in chemical sensing in non-carnivorous plants, suggesting Venus flytraps may be able to detect chemical changes related to prey capture, in addition to touch sensitivity.

"Of the upregulated transcripts that were predicted to be secreted, the researchers were able to confirm all were actively secreted using proteomic screening of the flytrap's digestive fluid. The researchers also used electron microscopy to study the ultrastructure of the trap's glands, finding specialized cell layers involved in active secretion, nutrient transport, lipid energy stores, and protein biosynthesis necessary for trap function."

Comment: this is a complex lifestyle for a plant, but it makes it easy to have nitrogen as well as other plant nutrients from the protein of the insects. It involves switching the use of root genes that control root absorption of nutrients, as well as insect defense chemicals. Again an example of complexity that works for survival. Note most plants don't need all this complexity to survive. Shows how the bush of life developed all its variations through complexity

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