Rewiring of auxin signaling under persistent shade

• Autores: Pucciariello, Ornella; Legris, Martina; Costigliolo Rojas, Cecilia; Iglesias, María José; Hernando, Carlos Esteban; Dezar, Carlos; Vazquez, Martín P.; Casal, Jorge José
• Año de publicación: 2018
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Proceedings of the National Academy of Sciences of the United States of America; Vol.115, no.21; 5612-5617; http://www.pnas.org
• Materia: MIR393; PHYTOCHROME BPIF4; AUXINAUXIN; RECEPTOR AUXIN; AUXIN RESPONSE FACTOR 6; PHYTOCHROME B; PHYTOCHROME INTERACTING FACTOR 4; RECEPTOR; TRANSCRIPTION FACTOR; UNCLASSIFIED DRUG; ARABIDOPSIS PROTEIN; INDOLEACETIC ACID DERIVATIVE; PHYTOHORMONE
• Institución: Universidad de Buenos Aires. Facultad de Agronomía

Fil: Pucciariello, Ornella. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.
Fil: Legris, Martina. CONICET. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires. Buenos Aires, Argentina.
Fil: Costigliolo Rojas, Cecilia. CONICET. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires. Buenos Aires, Argentina.
Fil: Iglesias, María José. CONICET. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires. Buenos Aires, Argentina.
Fil: Hernando, Carlos Esteban. CONICET. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires. Buenos Aires, Argentina.
Fil: Dezar, Carlos. Instituto de Agrobiotecnología de Rosario. Rosario, Argentina.
Fil: Vazquez, Martín P. Instituto de Agrobiotecnología de Rosario. Rosario, Argentina.
Fil: Casal, Jorge José. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.
Light cues from neighboring vegetation rapidly initiate plant shade - avoidance responses. Despite our detailed knowledge of the early steps of this response, the molecular events under prolonged shade are largely unclear. Here we show that persistent neighbor cues reinforce growth responses in addition to promoting auxin - responsive gene expression in Arabidopsis and soybean. However, while the elevation of auxin levels is well established as an early event, in Arabidopsis, the response to prolonged shade occurs when auxin levels have declined to the prestimulation values. Remarkably, the sustained low activity of phytochrome B under prolonged shade led to (i) decreased levels of PHYTOCHROME INTERACTING FACTOR 4 (PIF4) in the cotyledons (the organs that supply auxin) along with increased levels in the vascular tissues of the stem, (ii) elevated expression of the PIF4 targets INDOLE-3-ACETIC ACID 19 (IAA19) and IAA29, which in turn reduced the expression of the growth-repressive IAA17 regulator, (iii) reduced abundance of AUXIN RESPONSE FACTOR 6, (iv) reduced expression of MIR393 and increased abundance of its targets, the auxin receptors, and (v) elevated auxin signaling as indicated by molecular markers. Mathematical and genetic analyses support the physiological role of this system - level rearrangement. We propose that prolonged shade rewires the connectivity between light and auxin signaling to sustain shade avoidance without enhanced auxin levels.
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