Part
Seven - Flowering Plants: Form and Function 743
39. Plant Responses to Environmental Challenges 836
39.1
How Do Plants Deal with Pathogens?
837
Plants seal off infected parts to
limit damage 837
Some plants have potent chemical defenses
against pathogens 838
The hypersensitive response is a localized
containment strategy 838
Systemic acquired resistance is a
form of long-term “immunity”
839
Some plant genes match up with pathogen
genes 839
Plants develop specific immunity to
RNA viruses 840
39.2 How Do Plants Deal with Herbivores?
840
Grazing increases the productivity
of some plants 840
Some plants produce chemical defenses
against herbivores 841
Some secondary metabolites play multiple
roles 841
Some plants call for help 842
Many defenses depend on extensive
signaling 842
Recombinant DNA technology may confer
resistance to insects 842
Why don’t plants poison themselves?
844
The plant doesn’t always win
844
39.3 How Do Plants Deal with Climate
Extremes? 845
Some leaves have special adaptations
to dry environments 845
Plants have other adaptations to a
limited water supply 846
In water-saturated soils, oxygen is
scarce 846
Plants have ways of coping with temperature
extremes 847
39.4 How Do Plants Deal with Salt
and Heavy Metals? 848
Most halophytes accumulate salt 848
Halophytes and xerophytes have some
similar adaptations 848
Some habitats are laden with heavy
metals 849
