Rapid maize leaf and immature ear responses to UV-B radiation

CASATI P.; DARREN MORROW; JOHN FERNANDES; VIRGINIA WALBOT

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

Plants have evolved adaptations to environmental factors, including solar radiation. In addition to acting as a developmental and physiological signal, UV-B photons also cause cellular damage. Elevated UV-B radiation has pleiotropic effects on plant development, morphology, and physiology, but the regulation of systemic responses is not well-understood. To gain a better understanding of the initial events in UV-B acclimation, we have analyzed a 10min to 1h time course of transcriptome responses in irradiated and shielded leaves, and immature maize ears to unravel the systemic physiological and developmental responses in exposed and shielded organs.  To identify metabolites as possible signaling molecules, we looked for compounds that increased within 5-90 min in both irradiated and shielded leaves, to explain the kinetics of profound transcript changes within 1h.   We found that myoinositol is one such candidate metabolite, and it also has support from RNA profiling: after 1h UV-B, transcripts for myoinositol-1-phosphate synthase, are decreased in both irradiated and shielded leaves suggesting down-regulation of biogenesis.   We also demonstrate that if 0.1mM myoinositol is applied to leaves of greenhouse maize, some metabolites that are changed by UV-B are also changed similarly by the chemical treatment.  Therefore, this metabolite can partially mimic UV irradiation.