Dynamic Changes to Endogenous Germination Inhibitors in Cercis chinensis Seeds during Dormancy Release

Abstract

The purpose of this study was to determine whether Cercis chinensis seeds contain endogenous germination inhibitors, and if so, to clarify the dynamic changes to the inhibitors during dormancy release. A cabbage seed germination test was conducted to assess the seed extract activities during dormancy release. The endogenous inhibitor components were analyzed by gas chromatography–mass spectrometry and the dynamic changes to the endogenous inhibitors were analyzed by high-performance liquid chromatography. The analyses revealed 1,2,3-benzenetriol (phenolic compound) in the seedcoat is a water-soluble endogenous inhibitor, and the IC50 (the concentration at which 1,2,3-benzenetriol inhibited radicle growth of cabbage seeds by 50%) of 1,2,3-benzenetriol was 51.2 µg⋅mL–1. During dormancy release, the seed 1,2,3-benzenetriol content decreased to 17.7 µg⋅mL–1 (stratified for 60 days) from 561.4 µg⋅mL–1 (control). The abscisic acid (ABA) content exhibited the same tendency, decreasing from 5.6 ng⋅mL–1 to 0.5 ng⋅mL–1 after 60-day stratification. Exogenous ABA was highly inhibitory toward cabbage seed germination, with an IC50 of 1.5 ng⋅mL–1. These results indicate that ABA and 1,2,3-benzenetriol are important endogenous inhibitors in C. chinensis seeds, wherein they regulate seed dormancy, even at low concentrations.