ABSTRACT
Nitrate reductase (NR) and peroxidase (POX) are important enzymes involved in the metabolism of reactive oxygen (ROS) and nitrogen species in leaves of wheat (Triticum aestivum L.) seedlings. It has been confirmed that NR activity in wheat leaves depends on the light conditions and the presence of nitrates during the cultivation of the seedlings, and it is regulated by the molybdenum cofactor and phosphorylation. In the present study, confocal microscopy and EPR spectroscopy studies showed that the addition of nitrite, a product of NR, increased the level of nitric oxide (NO). This increase was prevented by the addition of sodium azide, an inhibitor of NR. The results suggest that in wheat leaves one of the key functions of NR is the formation of the signaling NO molecule. Cultivation of green plants under conditions of prolonged (4 days) darkness, a strong stress factor for photosynthesizing cells, decreased the activity of NR. Moreover, darkness induced significant elevation of the POX activity that was prevented by the addition of nitrate to the growth medium. It is proposed that the changes in light conditions result in the competition between nitrate- and ROS-metabolizing activities of POX in leaves, and a possible interaction between NR and POX controls the levels of NO and ROS in the leaf tissue.
Subject(s)
Nitrate Reductase/metabolism , Nitric Oxide/metabolism , Plant Leaves/enzymology , Plant Proteins/metabolism , Triticum/enzymology , Darkness , Gene Expression Regulation, Enzymologic , Light , Nitrate Reductase/genetics , Nitrites/metabolism , Plant Leaves/genetics , Plant Leaves/metabolism , Plant Leaves/radiation effects , Plant Proteins/genetics , Triticum/genetics , Triticum/metabolism , Triticum/radiation effectsABSTRACT
The content of soluble proteins and individual polypeptides was studied in calluses of buckwheat Fagopyrum tataricum (L.) Gaertn with different morphogenic potential. The morphogenic callus had a higher content of soluble proteins and cyclic pattern of changes in this index during passaging, which seems to be due to formation of proembryogenic cell complexes. Comparison of the protein patterns of the calluses demonstrated differences in composition and content of individual components. Morphogenic (35 and 73 kDa) and nonmorphogenic callus-specific proteins (16 and 62 kDa) have been revealed.
Subject(s)
Fagopyrum/growth & development , Morphogenesis , Plant Proteins/analysis , Biomarkers/analysis , Fagopyrum/chemistry , Fagopyrum/cytology , Peptides/analysisABSTRACT
The effect of salicylic acid on the content of soluble proteins and individual polypeptides in Tatar buckwheat Fagopyrum tataricum calluses differing in ability for morphogenesis was studied. Changes in the protein composition of the calluses cultivated in the dark and in the light indicated the higher sensitivity of the non-morphogenic callus. Different response of callus cultures to salicylic acid and conditions of cultivation (light, darkness) is suggested to be associated with the antioxidant defense system, which is, in particular, characterized by the hydrogen peroxide content in the calluses. Salicylic acid increased the H2O2 content in non-morphogenic calluses more strongly than in morphogenic calluses, and the difference was more significant for the calluses cultivated in the light.
