How Plants Send Email: Update
href=”crev07.htm#plant17″>07/13/2001 headline), we reported the startling finding that plants talk to themselves in email. What’s new in this field? Is there really an interplant intranet?
In the Oct. 5 issue of Current Biology,1 Norman, Frederick and Sieburth report evidence that a signal molecule named BYPASS1 is sent from the roots to the tips of the plant, and suppresses the growth of leaves. It acts as a negative regulator of plant growth hormones.
Plant growth hormones are produced in the tips of shoots. With too much growth hormone, leaves might grow too rapidly without knowing when the roots are struggling to find water, are having trouble getting through compacted soil, or fighting other harsh conditions. The roots need to be able to regulate leaf growth, therefore, and must be able to turn up the release of hormone only when the supply is adequate. The report on EurekAlert describes the control like a faucet handle that the root turns, but since the flow is at the shoot, the handle is really up where the leaves are. By sending this chemical signal up the network, the root has remote control over the spigot of growth hormone: something akin to switch remotely operated by a computer system administrator, who sends a correctly-formatted message the switch understands.
This explains how the same plant can look different depending on where it grows. Plants are composed of cells without a central nervous system or brain, yet the various parts need to act in concert. A plant can’t just walk away in tough times to look for greener pastures; it has to respond as a unit to changing conditions. The solution is a coordinated system of signals, feedback and regulatory functions. This study shows that roots are not just sending water and nutrients blindly upward, unaware of the conditions above ground. They are sending chemical signals to keep in touch with the leaf tips. Undoubtedly this is two-way communication, because the roots also must be informed of conditions above ground.
BYPASS1, a gene that codes for a carotenoid compound, is one more example of signal transduction, or “email,” in plants. The July 2001 headline spoke of messenger RNA used for signalling. Undoubtedly proteins and other chemical compounds as well are used in the interplant intranet to convey messages. Each chemical needs a receptor at the destination that understands the message. A plant, therefore, comprises an information processing system. Because information is passed throughout the branching pathways inside a plant, with sources and destinations defined, containing messages that are translated and understood and acted upon, the analogy to email over an intranet is an apt one.
Overarching this system is a network of networks. Different species of plants are also able to communicate with each other through the underground pipeline (see 06/17/2004 headline). This shows that the local area networks of individual plants are combined into a wide-area network, or internet. Information processing over a communication network is therefore the foundation of ecology:
Plant architecture is regulated by endogenous developmental programs, but it can also be strongly influenced by cues derived from the environment. For example, rhizosphere conditions such as water and nutrient availability affect shoot and root architecture; this implicates the root as a source of signals that can override endogenous developmental programs. …
The BPS1 expression profile clustered with a group of genes containing many kinases and transcription factors proposed to possibly function in a signaling network.1
Another article on EurekAlert discussed how researchers at Duke University are following one particular email message, a protein regulator in root cells. The scientists “made the surprising finding that the … protein is one means by which one root cell ‘talks’ to another to instruct it to develop in a certain way.”
1Norman, Frederick and Sieburth, “BYPASS1 Negatively Regulates a Root-Derived Signal that Controls Plant Architecture,” Current Biology, Volume 14, Issue 19, 5 October 2004, Pages 1739-1746, doi:10.1016/j.cub.2004.09.045.
When you send an email to a friend, it presupposes a large infrastructure of computers, routers, wires, and software. Without them, your message would sit in your computer and go nowhere. Your message is formatted into packets according the standards of internet protocol. Every piece of hardware and software in the network has to understand the protocol. It has to be able to read the header to properly route the packet from the source to the destination. Some messages can be broadcast to a group of recipients, or to everyone on the network. Some require acknowledgement before action; others, like a message in a bottle, can be picked up by any recipient. Different protocols provide many different services. Somehow, a plant accomplishes the same thing. It can send messages to individuals, groups, or “anyone online.” The receptors understand the messages and act accordingly.
The internet is a relatively new human invention that has revolutionized society. It didn’t just happen. It is the result of many efforts initiated by intelligent designers who dreamed of establishing a robust communications system. As we pat ourselves on the back for our communications network, now we find that plants had one all along. Think of the messaging going on from the roots of a giant redwood to the topmost leaves, and then all the messages being passed underground from plant to plant. It wouldn’t be surprising to find out someday that plants are already programmed with spam filtering, security and antiterrorism surveillance and maybe even innovations we have not even imagined yet.
Signal transduction – the passing and recognition of messages – is a defining characteristic of life. All living things are continually in the communication business. Single cells have elaborate signal transduction mechanisms for recognizing “self” and “other” entities, and for regulating all the machines in the molecular factory. Cells communicate with other cells. Within multicellular organisms, cells communicate within the body and without. Plants, animals and humans are constantly sending and receiving messages. Even the machines humans make, from railroad semaphores to telegraphs to wireless internet communications, are extensions of our own intelligent signalling systems. Inanimate matter does not do any of this on its own. Solids, liquids and gases can exchange energy through conduction, convection and radiation, but neither send nor understand signals that allow them to make decisions, unless programmed by intelligent design. Since signaling is a fundamental property of life, why should anyone presume it could emerge from nonlife? Would it not make more sense to assume that there is a living Creator who is a communicator by nature, and that he extended his intelligence to the life he designed?
Non-sentient life might be considered analogous to our most advanced human robotics, with robust engineering design that allows it to respond to changing conditions (see 09/22/2004 headline). Into humans, however, the Source of all communication – the Word – imbued an image of his own sentience, so that we can not only recognize and respond to messages, but understand them. To these alone he shared the greatest communication of all (Hebrews 1:1-3).