Biological complexity: plant root growth stimulation (Introduction)

by David Turell , Saturday, June 08, 2019, 19:01 (1995 days ago) @ David Turell

In low nitrogen situations plant root growth is stimulated by specialized hormones:

https://www.sciencedaily.com/releases/2019/06/190607110518.htm

"As sessile organisms, plants rely on their ability to adapt the development and growth of their roots in response to changing nutrient conditions. One such response, known to be displayed by plants grown in low nitrogen conditions, is the elongation of primary and lateral roots to explore the surrounding soil.

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" As soon as plants run into nitrogen deficiency, they immediately induce a foraging response, in which roots elongate to explore a larger soil volume. The regulatory mechanisms underlying this nitrogen-dependent root response were previously unknown. Researchers from the IPK in Gatersleben have now discovered that a class of steroid hormones modulate root foraging under low nitrogen conditions and thereby determine the extent of this response.

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"the researchers were able to show that BSK3, a brassinosteroid signaling kinase, is modulating the extent of root elongation under low nitrogen. Further, they demonstrated that mild nitrogen deficiency activates brassinosteroid signaling by upregulating the transcript levels of the brassinosteroid co-receptor BAK1 that enhances the sensitivity of root cells to brassinosteroids. (my bold)

"The results reveal a previously unknown role of brassinosteroid-type plant hormones in shaping root systems in response to nutrient deficiencies. This novel insight allows a deeper understanding of the regulation behind adaptive responses of plants to changes in nitrogen availability, but also provides a perspective for practical application in agriculture."

Comment: This finding presents the usual problem for Darwin-style evolutionary theory. The bolded molecule is a giant enzyme, with exact structure to provide the necessary result in action. Of all the possible structures to chose from, how did unguided evolution find such a molecule? Since this is an issue of survival, this mechanism had to be part of the original design of the plant.