Delayed germination of Brassica parachinensis seeds by coumarin involves decreased GA4 production and a consequent reduction of ROS accumulation

The plant allelochemical coumarin effectively inhibits the germination of Brassica parachinensis (B. parachinensis) seeds. Quantification of endogenous phytohormones showed that contents of abscisic acid (ABA), ABA glucose ester, gibberellin A20 (GA20), GA3, GA15, GA24, GA9 and GA4 were higher in ge...

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Bibliographic Details
Published in:Seed science research 2021-09, Vol.31 (3), p.224-235
Main Authors: Chen, Bing-Xian, Peng, Yuan-Xuan, Yang, Xue-Qin, Liu, Jun
Format: Article
Language:English
Subjects:
Abscisic acid
Accumulation
Brassica
Brassica rapa parachinensis
Catalase
Coumarin
Crops
Enzymes
Germination
Gibberellins
Lettuce
Peroxidase
Plant hormones
Potassium
Reactive oxygen species
Research Paper
Rice
Seed germination
Seedlings
Seeds
Spectrophotometry
Superoxide anions
Superoxide dismutase
β-Amylase
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Summary:The plant allelochemical coumarin effectively inhibits the germination of Brassica parachinensis (B. parachinensis) seeds. Quantification of endogenous phytohormones showed that contents of abscisic acid (ABA), ABA glucose ester, gibberellin A20 (GA20), GA3, GA15, GA24, GA9 and GA4 were higher in germinating seeds than in seedlings. Moreover, the presence of coumarin significantly reduced the content of bioactive GA4 which is thought to positively regulate seed germination. Histochemical staining and spectrophotometry of reactive oxygen species (ROS) revealed that exogenous GA3 and GA4+7 could effectively promote the production of endogenous ROS during germination and that the GA synthesis inhibitor paclobutrazol could effectively inhibit production of ROS. Coumarin significantly inhibited the accumulation of ROS, especially superoxide anion radical (${\rm O}_2^{{\cdot}{-}} $). This inhibitory effect could be restored by the addition of exogenous GA3 and GA4+7. Coumarin also inhibited the activity of the ROS-degrading enzymes such as superoxide dismutase, catalase and peroxidase as well as β-amylase in seeds and seedlings. Taken together, we propose a model for the regulation of seed germination in B. parachinensis by coumarin, Gas and ROS, in which coumarin may delay seed germination by reducing endogenous GA4, thus decreasing the accumulation of ROS.
ISSN:0960-2585
1475-2735
DOI:10.1017/S0960258521000167