Green means go: Green light promotes hypocotyl elongation via BRs

Generally, light inhibits hypocotyl elongation. Like red and blue light, green light was previously reported to inhibit hypocotyl elongation in several plants. Here, Hao et al. discovered that the inhibition of hypocotyl growth by green light is due to wavelength impurities in the green lights used. Commercial green LED lights of 525 nm and 550 nm wavelengths generate blue and red light tails respectively, which constitute impurities, hence inhibit hypocotyl growth. Pure green light of 550 nm (Green 550) promotes hypocotyl elongation. However, like other light wavelengths, it also promotes apical hook opening and cotyledon separation. The influence of Green 550 was shown not to be photosynthesis dependent or due to effects on germination. Green 500 promotes hypocotyl elongation via the brassinosteroid signaling pathway and acts as shade signals for plants to adapt under canopy. The authors stipulated that Green 500 effects on hypocotyl elongation may not be mediated by known photoreceptor, suggesting a need to identify a green light receptor. (Summary by Idowu Arinola Obisesan, @IdowuAobisesan) Plant Cell 10.1093/plcell/koad022