title: Putative role of proteins involved in detoxification of reactive oxygen species in the early response to gravitropic stimulation of poplar stems.
abstract: Gravity perception and gravitropic response are essential for plant development. In herbaceous species it is widely accepted that one of the primary events in gravity perception involves the displacement of amyloplasts within specialized cells. However the signaling cascade leading to stem reorientation is not fully known especially in woody species in which primary and secondary growth occur. Several different second messengers and proteins have been suggested to be involved in signal transduction of gravitropism. Reactive oxygen species (ROS) have been implicated as second messengers in several plant hormone responses. It has been shown that ROS are asymmetrically generated in roots by gravistimulation to regions of reduced growth. Proteins involved in detoxification of ROS and defense were identified by mass spectrometry: i.e., Thioredoxin h (Trx h), CuZn superoxide dismutase (CuZn SOD), ascorbate peroxidase (APX2), oxygen evolving enhancer 1 (OEE1), oxygen evolving enhancer 2 (OEE2), and ATP synthase. These differentially accumulated proteins that correspond to detoxification of ROS were analyzed at the mRNA level. The mRNA levels showed different expression patterns than those of the corresponding proteins, and revealed that transcription levels were not completely concomitant with translation. Our data showed that these proteins may play a role in the early response to gravitropic stimulation.
authors.affiliation: Laboratoire de Biologie et Physiologie Végétales; Département de Biologie; Faculté des Sciences de Tunis; Tunis, Tunisia.
authors.forename: Azri
authors.initials: A
authors.lastname: Wassim
authors.affiliation: Laboratoire de Biologie et Physiologie Végétales; Département de Biologie; Faculté des Sciences de Tunis; Tunis, Tunisia.
authors.forename: Ben Rejeb
authors.initials: BR
authors.lastname: Ichrak
authors.affiliation: Laboratoire de Biologie et Physiologie Végétales; Département de Biologie; Faculté des Sciences de Tunis; Tunis, Tunisia.
authors.forename: Ammar
authors.initials: A
authors.lastname: Saïda
mesh_terms: D006112:Gravitation; D018522:Gravitropism / Q000235:genetics; D018466:Gravity Sensing / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D018547:Plant Stems / Q000254:growth & development / Q000378:metabolism*; D032107:Populus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species
keywords: gravitropism; mass spectrometry; poplar; reactive oxygen species (ROS)