Suppression of Reactive Oxygen Species Accumulation in Chloroplasts Prevents Leaf Damage but Not Growth Arrest in Salt-Stressed Tobacco Plants

ANABELLA F. LODEYRO; MARIANA GIRÓ; HUGO O. POLI; GABRIEL BETTUCCI; ADRIANA CORTADI; ALEJANDRO M. FERRI; NÉSTOR CARRILLO

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2016

1932-6203

Crop yield reduction due to salinity is a growingagronomical concern in many regions. Increased production of reactive oxygenspecies (ROS) in plant cells accompanies many abiotic stresses includingsalinity, acting as toxic and signaling molecules during plant stressresponses. While ROS are generated in various cellular compartments,chloroplasts represent a main source in the light, and plastid ROS synthesisand/or elimination have been manipulated to improve stress tolerance.Transgenic tobacco plants expressing a plastid-targeted cyanobacterialflavodoxin, a flavoprotein that prevents ROS accumulation specifically inchloroplasts, displayed increased tolerance to many environmental stresses,including drought, excess irradiation, extreme temperatures and iron starvation.Surprisingly, flavodoxin expression failed to protect transgenic plants againstNaCl toxicity. However, when high salt was directly applied to leaf discs, flavodoxindid increase tolerance, as reflected by preservation of chlorophylls,carotenoids and photosynthetic activities. Flavodoxin decreased salt-dependentROS accumulation in leaf tissue from discs and whole plants, but this declinedid not improve tolerance at the whole plant level. NaCl accumulation in roots,as well as increased osmotic pressure and salt-induced root damage, were notprevented by flavodoxin expression. The results indicate that ROS formed inchloroplasts have a marginal effect on plant responses during salt stress, andthat sensitive targets are present in roots which are not protected byflavodoxin.