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Title: Role of H<sub>2</sub>O<sub>2</sub> and cell wall monoamine oxidases in germination of <i style="">Vigna</i> <i style="">radiata </i>seeds
Authors: Verma, Giti
Sharma, Samir
Keywords: Aromatic monoamines (AMA)
Monoamine oxidases (MAO)
Protein reserve mobilization
Reactive oxygen species (ROS)
Seed germination
Issue Date: Aug-2010
Publisher: CSIR
Abstract: Plant cell wall expresses monoamine oxidases (MAOs) that catalyze oxidation of secreted amines and produce H<sub>2</sub>O<sub>2</sub> in the process. The H<sub>2</sub>O<sub>2,</sub> so produced is used by cell wall peroxidases for lignification of cell wall or for plant defense. The natural substrates for these MAOs are elusive, but polyamines and certain catecholamines have been proposed as candidates. Reactive oxygen species are also known to act as signaling molecules controlling plant metabolism. Mungbean (<i style="">Vigna radiata</i>) has long served as the plant model of choice while studying molecular programs followed during germination and seed development. In this study, we tested the effect of externally added MAO substrates epinephrine and H<sub>2</sub>O<sub>2</sub> on storage protein mobilization in germinating seeds of <i style="">Vigna radiata. </i>The seeds were imbibed in the presence of 50 <img src='/image/spc_char/micro.gif' border=0>M epinephrine and 10 <img src='/image/spc_char/micro.gif' border=0>M H<sub>2</sub>O<sub>2</sub>. These low concentrations of the two compounds were used to exclude direct effects on proteolysis and were arrived at after testing a range of the two and choosing the most effective concentration. These seeds showed 11% and 7% decrease in fresh weight respectively, indicating greater storage mobilization and a corresponding 19% and 46% increase in axis length as compared to untreated seeds. Soluble protein in seeds treated with epinephrine and H<sub>2</sub>O<sub>2</sub> decreased significantly by 34% and 33% as compared to untreated seeds. Electrophoretic analysis of seed proteins revealed a startling and selective depletion of storage proteins in treated seeds. The results indicated a clear involvement of H<sub>2</sub>O<sub>2</sub> in storage protein mobilization in the cotyledons. We propose that H<sub>2</sub>O<sub>2</sub> generated within cell walls of seeds serves as a signaling molecule guiding germination events, including protein reserve mobilization.
Description: 249-253
ISSN: 0975-0959 (Online); 0301-1208 (Print)
Appears in Collections:IJBB Vol.47(4) [August 2010]

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