부산대학교 도서관

Major strides have been made over the past decade in elucidating the mechanisms that mediate shade-avoidance responses. The canonical PHYTOCHROME INTERACTING FACTOR (PIF)–auxin pathway that begins with inactivation of phytochrome B (phyB) by a low red:far-red (R:FR) ratio, and that leads to increased elongation, has been thoroughly characterized in arabidopsis (Arabidopsis thaliana) seedlings. Nevertheless, studies in other life stages and plant species have demonstrated the role of other wavelengths, photoreceptors, and hormones in the orchestration of shade-avoidance responses. We highlight recent developments that illustrate how canopy light cues regulate signaling through auxin, gibberellins (GAs), jasmonic acid (JA), salicylic acid (SA), abscisic acid (ABA), and strigolactones (SLs) to modulate key aspects of plant growth, metabolism, and defense. Plants obtain information about the proximity of other plants by using specialized photoreceptors that cover a wide range of wavelengths. Photoreceptors regulate shade avoidance via two major, interrelated mechanisms: (i) direct inhibition of transcription factors of the PIF family, and (ii) suppression of the function of the COP1/SPA E3 ligase complex. In addition to auxin, other hormones including gibberellin (GA), jasmonic acid (JA), abscisic acid (ABA), and strigolactone (SL) are emerging as central regulators of shade avoidance. When competition for light is strong, plants prioritize responses that improve their capacity to forage for light while becoming more susceptible to herbivores and pathogens. Attenuation of JA responses under low red:far-red ratios is dependent on PIF-mediated changes in JA metabolism, which divert JA molecules away from the formation of bioactive conjugates. [ABSTRACT FROM AUTHOR]