Plant Defense Characteristics and Hypotheses in Birch Species
Novriyanti, Eka;Aoyama, Chiho;Watanabe, Makoto;Koike, Takayoshi
Permalink : http://hdl.handle.net/2115/44673
KEYWORDS : Birch (Betula);chemical defense;physical defense;trade-off relation;proposed defense models
Abstract
Birches employ defense when under pressure, either biotic or abiotic or both. They have at least three types of defense against herbivores, involving physical, chemical and phenological strategies, whether the defense is constitutive or induced. Leaves usually use both types of defense, whereas woody parts (stems, branches, or twigs) deploy mostly chemical defense. Other studies scarcely differentiate between proposed plant defense models such as CNBH and GDBH, and the defensive responses of birches, since there is a large variation in defensive responses. The evidence supports neither the carbon-nutrient balance (CNB) nor the growth-differentiation balance (GDB) hypothesis in birch defense, indicating that defense is genetically regulated. In our review, we may conclude that birches deploy their various defenses in parallel, since these derive from distinct chemical and physical mechanisms.
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