title: Antioxidant and HSP70B responses in Chlamydomonas reinhardtii genotypes with different resistance to oxidative stress.
abstract: Today, the information from model species that differ in their resistance to oxidative stress and the determination of suitable plant markers for screening stress-resistant genotypes are essential for better understanding of plant stress responses and for selection. Here we aimed to assess the differences in antioxidant and HSP70B responses to paraquat treatment between genotypes susceptible and resistant to oxidative stress. Four genotypes of Chlamydomonas reinhardtii were chosen as a model of plant cells: two susceptible genotypes: wild type and paraquat-sensitive; and two paraquat-resistant genotypes: with high and moderate resistance. Varying responses to paraquat treatment were found depending on the genotype and paraquat concentrations. High paraquat concentrations (>50μM) were shown to be very stressful for all C. reinhardtii genotypes, leading to inhibition of enzyme activity. Only the paraquat-sensitive genotype responded to low-level paraquat treatment with a marked enhancement of SOD, CAT, GST activities. The lack of statistically significant response measured as SOD, CAT, GST activities in WT and resistant genotypes could be considered as an indication of absence of strong oxidative stress. This could relate to higher levels of endogenous SOD and CAT activities characteristic of moderately and highly paraquat-resistant genotypes. The response to lower paraquat concentrations evaluated as HSP70B accumulation was proportional to the level of genotype susceptibility to PQ. New evidence is provided that low-level oxidative stress impacts the antioxidant and HSP70B responses differently depending on the genotype resistance. In light of the still unresolved challenge for identification of reliable characters for screening of genotype resistance/susceptibility to oxidative stress, our study demonstrates that HSP70B accumulation could be used as an early marker for induced oxidative stress in the studied genotypes. The obtained results that the most pronounced differences in the antioxidant and HSP70B response were found between the two susceptible genotypes provoke us to convey future experiments with other susceptible genotypes.
authors: Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113 Sofia, Bulgaria. Electronic address: Stephanie.Chankova@yahoo.com.
authors: Stephka G
authors: SG
authors: Chankova
authors: Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113 Sofia, Bulgaria. Electronic address: zheni.dimova@gmail.com.
authors: Evgeniya G
authors: EG
authors: Dimova
authors: Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113 Sofia, Bulgaria. Electronic address: zmitrovska@yahoo.com.
authors: Zhana
authors: Z
authors: Mitrovska
authors: Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113 Sofia, Bulgaria. Electronic address: daniela.miteva@abv.bg.
authors: Daniela
authors: D
authors: Miteva
authors: A.N. Bach Institute of Biochemistry, Russian Academy of Sciences, Leninskii pr., 33, Moscow 119071, Russia. Electronic address: daryamokerova@mail.ru.
authors: Dariya V
authors: DV
authors: Mokerova
authors: Bulgaria Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Acad G. Bonchev Street, Building 21, 1113 Sofia, Bulgaria. Electronic address: pyonova@yahoo.com.
authors: Petranka A
authors: PA
authors: Yonova
authors: A.N. Bach Institute of Biochemistry, Russian Academy of Sciences, Leninskii pr., 33, Moscow 119071, Russia. Electronic address: NYurina@inbi.ras.ru.
authors: Nadezhda P
authors: NP
authors: Yurina
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics*; D004785:Environmental Pollutants / Q000633:toxicity; D004789:Enzyme Activation / Q000187:drug effects; D005838:Genotype; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects* / Q000235:genetics; D010088:Oxidoreductases / Q000378:metabolism*; D010269:Paraquat / Q000633:toxicity*; D010940:Plant Proteins; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D004785:Environmental Pollutants; D018840:HSP70 Heat-Shock Proteins; C102156:HSP70B protein, Chlamydomonas; D010940:Plant Proteins; D015800:Protozoan Proteins; D010088:Oxidoreductases; D010269:Paraquat
keywords: Antioxidant enzymes; Cell resistance; Chlamydomonas; Chloroplast chaperones; Glutathione-S-transferase; Paraquat