Authors: Qing Sang, Lusheng Fan, Tianxiang Liu, Yongjian Qiu, Juan Du, Beixin Mo, Meng Chen and Xuemei Chen.
Nature Communications (2023)
Editor's view: Plants respond to light and temperature changes via the photoreceptor phytochrome B and the phytohormone auxin. Here the authors reveal microRNA156 as a previously uncharacterized developmental signal that gates environmentally regulated plant growth by licensing auxin sensitivity.
Abstract: MicroRNAs (miRNAs) play diverse roles in plant "development, but whether and how miRNAs participate in thermomorphogenesis remain ambiguous. Here we show that HYPONASTIC LEAVES 1 (HYL1)—a key component of miRNA biogenesis—acts downstream of the thermal regulator PHYTOCHROME INTERACTING FACTOR 4 in the temperature-dependent plasticity of hypocotyl growth in Arabidopsis. A hyl1-2 suppressor screen identified a dominant dicer-like1 allele that rescues hyl1-2’s defects in miRNA biogenesis and thermoresponsive hypocotyl elongation. Genome-wide miRNA and transcriptome analysis revealed microRNA156 (miR156) and its target SQUAMOSA PROMOTER-BINDING-PROTEIN-LIKE 9 (SPL9) to be critical regulators of thermomorphogenesis. Surprisingly, perturbation of the miR156/SPL9 module disengages seedling responsiveness to warm temperatures by impeding auxin sensitivity. Moreover, miR156-dependent auxin sensitivity also operates in the shade avoidance response at lower temperatures. Thus, these results unveil the miR156/SPL9 module as a previously uncharacterized genetic circuit that enables plant growth plasticity in response to environmental temperature and light changes."