Light regulation of plant defense.
Precise allocation of limited resources between growth and defense is critical for plant survival. In shade-intolerant species, perception of competition signals by informational photoreceptors activates shade-avoidance responses and reduces the expression of defenses against pathogens and insects. The main mechanism underlying defense suppression is the simultaneous downregulation of jasmonate and salicylic acid signaling by low ratios of red:far-red radiation. Inactivation of phytochrome B by low red:far-red ratios appears to suppress jasmonate responses by altering the balance between DELLA and JASMONATE ZIM DOMAIN (JAZ) proteins in favor of the latter. Solar UVB radiation is a positive modulator of plant defense, signaling through jasmonate-dependent and jasmonate-independent pathways. Light, perceived by phytochrome B and presumably other photoreceptors, helps plants concentrate their defensive arsenals in photosynthetically valuable leaves. The discovery of connections between photoreceptors and defense signaling is revealing novel mechanisms that control key resource allocation decisions in plant canopies.
IFEVA, Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad de Buenos Aires, C1417DSE Buenos Aires, Argentina; email: ballare@ifeva.edu.ar.
Carlos L
CL
Ballaré
D003517:Cyclopentanes / Q000378:metabolism; D008027:Light; D054883:Oxylipins / Q000378:metabolism; D010786:Photoreceptor Cells / Q000378:metabolism*; D051939:Phytochrome B / Q000378:metabolism; D063245:Plant Development; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism; D018521:Plant Physiological Phenomena; D010944:Plants / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction
D003517:Cyclopentanes; D054883:Oxylipins; D051939:Phytochrome B; C011006:jasmonic acid; D020156:Salicylic Acid