life11e_ch36

key concept 36.1 Plants Develop in Response to the Environment

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As you learned in in Chapter 33, plants can’t move to get food and so must seek out resources above and below the ground. A number of unique features enable plants to obtain the resources they need to grow and reproduce:

Meristems. Plants have permanent collections of stem cells (undifferentiated, constantly dividing cells) that allow them to continue growing throughout their lifetimes.
Post-embryonic organ formation. Unlike animals, plants can initiate development of new organs such as leaves and flowers throughout their lifetimes.
Differential growth. Plants allocate resources to grow beneficial organs. For example, leaf growth allows plants to capture more sunlight or more roots permits greater water and nutrient uptake.

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Plants use several mechanisms to maintain dormancy; these mechanisms must be overcome before a seed can germinate.
Seed germination begins with imbibition and ends with the emergence of the radicle, or embryonic root, in a process that requires plants to sense environmental changes.
Plants respond to environmental cues during growth by the use of signal transduction pathways involving hormones and photoreceptors.
Scientists use genetic screens to identify genes involved in the control of growth and development.

Plants must continuously monitor their ever-changing environments and redirect their growth appropriately. For example, the amount of available light changes from day to night and from season to season. In addition, other plants are often vying for the available light, and plants modulate their growth to compete with their neighbors for this precious resource. As you will see in this chapter, several mechanisms have evolved in plants that enable them to *sense changes in their environments and trigger appropriate growth responses.

*connect the concepts This chapter is devoted to how plants regulate their growth in response to environmental signals. Chapter 38 is dedicated to how plants respond to environmental challenges such as pathogens, herbivory, and physical stresses.