William Sutherland


the plant’s water tubes under tension. If the soil lacks enough water, the tension becomes too great and the tubes fracture.”25


Intraspecific root zone communication works in a similar way, with chemical messages being transmitted across a botanic network called runners.


Many


herbal plants – clover, ground elder, reed, and strawberry, to name a few – utilize these internal networks to exchange information. Research at Radboud University Nijmegan in the Netherlands found that clover plants warned each other through runners when exposed to caterpillars. Nearby clovers immediately responded with VOC releases to make themselves less palatable.


VOCs (about 1700 different compounds from the various plant species) are released from leaves, flowers, or fruits. Green leaf volatiles (GLV), comprising 6- carbon aldehydes, alcohols and esters, are commonly emitted by plants in response to mechanical damage or herbivory.26 At the same time, an even more impressive number of VOCs are released in the root zone. Due to the great diversity of microbes, insects, and plant roots beneath the soil, up to 100,000 different chemicals are used.


Initials also play sensory and communication roles in autosignaling. They permit plants to perceive and communicate environmental conditions between their different parts. For example, plant stem cells rely on the hormone ethylene to determine when soil and other environmental conditions are favorable for growth. When such conditions are favorable, ethylene provides a signal to activate root and shoot initials that then divide to bring about growth and flowering, the latter in angiosperms, the dominant type of plant today.


This autosignaling is made possible by a movement protein, CmPP16 that carries information-bearing RNA from stems and leaves to faraway roots and flowers through tube-shaped sieve elements of the phloem.27 This information- bearing RNA is funneled to different parts of the plant through plasmodesmata (narrow channels) until companion cells at the intended destination points receive it and act upon its message.


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