Journal Article

Regulation of soybean seed germination through ethylene production in response to reactive oxygen species

Yushi Ishibashi, Yuka Koda, Shao-Hui Zheng, Takashi Yuasa and Mari Iwaya-Inoue

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 111, issue 1, pages 95-102
Published in print January 2013 | ISSN: 0305-7364
Published online November 2012 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcs240
Regulation of soybean seed germination through ethylene production in response to reactive oxygen species

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Background and Aims

Despite their toxicity, reactive oxygen species (ROS) play important roles in plant cell signalling pathways, such as mediating responses to stress or infection and in programmed cell death, at lower levels. Although studies have indicated that hydrogen peroxide (H2O2) promotes seed germination of several plants such as Arabidopsis, barley, wheat, rice and sunflower, the role of H2O2 in soybean seed germination is not well known. The aim of this study therefore was to investigate the relationships between ROS, plant hormones and soybean seed germination.

Methods

An examination was made of soybean seed germination, the expression of genes related to ethylene biosynthesis, endogenous ethylene contents, and the number and area of cells in the root tip, using N-acetylcysteine, an antioxidant, to counteract the effect of ROS.

Key Results

H2O2 promoted germination, which N-acetylcysteine suppressed, suggesting that ROS are involved in the regulation of soybean germination. H2O2 was produced in the embryonic axis after imbibition. N-Acetylcysteine suppressed the expression of genes related to ethylene biosynthesis and the production of endogenous ethylene. Interestingly, ethephon, which is converted to ethylene, and H2O2 reversed the suppression of seed germination by N-acetylcysteine. Furthermore, morphological analysis revealed that N-acetylcysteine suppressed cell elongation at the root tip, and this suppression was also reversed by ethephon or H2O2 treatments, as was the case in germination.

Conclusions

In soybean seeds, ROS produced in the embryonic axis after imbibition induce the production of endogenous ethylene, which promotes cell elongation in the root tip. This appears to be how ROS regulate soybean seed germination.

Keywords: Ethylene; reactive oxygen species; seed germination; Glycine max.

Journal Article.  4895 words.  Illustrated.

Subjects: Plant Physiology

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