Analysis of Leaf Proteome after UV-B Irradiation in Maize Lines Differing in Sensitivity

Paula Casati,Alma L Burlingame,Virginia Walbot,Xing Zhang

doi:10.1074/mcp.m500173-mcp200

Paula Casati, Alma L Burlingame + Show 2 more

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https://doi.org/10.1074/mcp.m500173-mcp200

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Abstract

UV-B radiation causes diverse morphological and physiological responses in plants, but the underlying mechanisms governing these integrated responses are unknown. In this study, we systematically surveyed responses of maize leaves to UV-B radiation using DIGE 2D gels and identified selected proteins by mass spectrometry and immunodetection analysis. To identify changes in protein accumulation in response to UV-B radiation, a line (b, pl W23) deficient in flavonoid sunscreen compounds and hence similar to commercial corn was used. In addition, its proteome in natural UV-B conditions was compared with that of two maize landraces from high altitudes (Cacahuacintle and Confite Puneño) that have improved UV-B tolerance. Protein patterns in adult maize leaves (Zea mays) were documented after growth for 21 days in sunlight depleted of UV-B radiation or growth in sunlight including an 8-h UV-B supplementation during 1 day in the field. We found that there is a very high correlation between previously documented mRNA accumulation assessed by microarray hybridization and quantitative real time reverse transcription-PCR and protein expression after UV-B irradiation in leaves of W23. Multiple isoforms were confirmed for some proteins; at least one protein, pyruvate, phosphate dikinase, is regulated post-translationally by phosphorylation by UV-B exposure. Proteins differentially regulated by UV-B radiation in W23 with higher levels under similar UV-B conditions in high altitude plants were also identified. These could be genetically fixed traits conferring UV-B tolerance and offer clues to specific adaptations to living in high ambient UV-B conditions.

Highlights

UV-B radiation causes diverse morphological and physiological responses in plants, but the underlying mechanisms governing these integrated responses are unknown
UV-B radiation induces the rapid activation of c-fos and c-jun [10, 11]; this induction is mediated through several signal transduction pathways [12, 13], including multiple MAP1 kinase pathways
Plant responses to UV-B radiation are likely to involve multiple signal transduction cascades; far, changes in intracellular calcium, calmodulin, serine/threonine kinases, and phosphatase activities have been implicated in UV-B radiation-mediated transcriptional activation of chalcone synthase [14, 15], which catalyzes an initial step in flavonoid sunscreen biosynthesis

Summary

Introduction

UV-B radiation causes diverse morphological and physiological responses in plants, but the underlying mechanisms governing these integrated responses are unknown. To identify changes in protein accumulation in response to UV-B radiation, a line (b, pl W23) deficient in flavonoid sunscreen compounds and similar to commercial corn was used. Proteins differentially regulated by UV-B radiation in W23 with higher levels under similar UV-B conditions in high altitude plants were identified. These could be genetically fixed traits conferring UV-B tolerance and offer clues to specific adaptations to living in high ambient UV-B conditions. UV-B radiation induces the rapid activation of c-fos and c-jun [10, 11]; this induction is mediated through several signal transduction pathways [12, 13], including multiple MAP1 kinase pathways. The abbreviations used are: MAP, mitogen-activated protein; 2D, two-dimensional; PPDK, pyruvate, phosphate dikinase; PE, polyester; CA, cellulose acetate; W, watts; TCTP, translationally controlled tumor protein; GPB-LR, guanine nucleotide-binding protein ␤ subunitlike protein; YLP, yucca leaf protein; eEF1, eukaryotic elongation factor 1; HSP, heat shock protein

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