This study has been undertaken to find out maize inbred(s) with high levels of glutathione S-transferases (GSTs, EC.2.5.1.18), the most studied stress inducible family enzyme, at the Molecular Breeding Laboratory of Plant Breeding Division, Bangladesh Agricultural Research Institute (BARI). The specific activities of GSTs were assayed towards model substrate 1-chloro-2,4-dinitrobenzene (CDNB). This year, fifteen inbreds have been investigated. Among them, significant variation was found in GST activity level. Inbred, CZ-17 showed the highest level of GST activity, followed by CZ-20 and CZ-8, while BIL-20 had the minimum. The stress responsibility of the genotypes with high activity level will be investigated in next experiments.
Stress, Gene, Ascorbic acid, Enzymes
Variety and Species
Environmental stresses (salinity, drought, heat/cold, light and other hostile conditions) trigger in plants oxidative stress, generating the formation of reactive oxygen species (ROS, leading to cell death by causing damage to proteins, lipids, DNA and carbohydrates.Among the enzymatic systems, GSH- and ascorbic acid dependent enzymes have important roles in stress combating by providing homeostasis against the ROS by scavenging them.Therefore,searching of high stress inducible GSTs, maize inbred lines have been screening to obtain a genotype with high GST activity that will be tested for stress responsibility.
ix-day old seedling of maize inbred lines, CZ-1, CZ-7, CZ-13, CZ-17, CZ-19, CZ-20, CZ-28, CZ-26, Cz-40, BIL, 20, BIL-22, BIL-29, BIL-31 and BIL-29, were used to extract protein. Crude enzyme was extracted from maize seedlings (whole plant) by homogenizing with an equal volume of 25 mM Tris-HCL buffer (pH 8.5), that contained 1 mM EDTA and 1% (w/v) ascorbate in a mortar and pestle.Protein concentration of each of the soluble extracts was determined by the method of Bradford (1976) with bovine serum albumin (BSA) as the protein standard.GST activity was determined spectrophotometrically (GENESIS 10 BIO, Thermo Scin) by the method of Rohman (2009) with some modifications. The reaction mixture contained 100 mM potassium phosphate buffer (pH 6.5), 1.5 mM reduced glutathione, 1 mM 1-chloro-2,4-dinitrobenzene (CDNB), and enzyme solutions in a final volume of 0.525 ml. The enzyme reaction was initiated by the addition of CDNB, and absorbance (A340) was monitored at 25˚C for 1 minute.
Research report 2009-10
The comparative results showed that CZ-17 (459.5 nmol/min/mg protein) had the highest level of GST activity followed by CZ-20 (454.8 nmol/min/mg protein) and CZ-8 (406.4 nmol/min/mg protein). BIL-20 had the lowest level of GST activity (291.2 nmol/min/mg protein). Other inbreds showed medium level of activity (300-400 nmol/min/mg protein). Most GSTs are reported to perform diverse catalytic as well as non-catalytic roles in detoxification of xenobiotics, prevention of oxidative damage and endogenous metabolism (Frova, 2003). Therefore, the higher level of GST activities of CZ-17, CZ-20 and CZ-8 might have higher detoxification and stress tolerant capacity compared to others.
Report/Proceedings