Water-soluble phenolic compounds in the coat control germination and peroxidase reactivation in Triticum aestivum seeds

Abstract

In this work, we investigated the inhibitory effects of water-soluble phenolic compounds (WSPCs) in the coat of after-ripening wheat (Triticum aestivum L.) seeds on the processes of germination and peroxidase reactivation. Wheat bran has a WSPC content of 862.5 lg gallic acid equivalent g -1 dry weight. When seeds were incubated in the water extract of bran, germination, peroxidase reactivation, and coleoptile and radicle growth were suppressed in a WSPC concentration-dependent manner. The inhibitory effects were significantly ameliorated by removing WSPCs from bran extract by treating with 1% insoluble polyvinylpolypyrrolidone. Pretreatment of seeds with 0.1% H 2 O 2 reduced the WSPC content in the coat, which was confirmed using Fourier transform infrared microspectroscopy. With H 2 O 2 pretreatment, seed germination, peroxidase reactivation, and post-germination seedling growth were significantly stimulated. Application of the known phenolics caffeic acid, feruic acid, or vanillin to the germination medium blocked seed germination and suppressed peroxidase reactivation. The results described here indicate that WSPCs act as endogenous inhibitors in the coat to control germination of Triticum aestivum seeds, and that inhibition of germination is at least partially caused by suppressing peroxidase reactivation.

Polyphenols leaching and seed dormancy in carob (Ceratonia siliqua L.) in relation to hot water treatment

“…The inhibitory effects of phenolic compounds on seed germination are still debated (Bewley et al 2013), they have been considered strictly associated to the regulation of seed coat permeability, and oxygen supply to embryos (Willemsen and Rice 1972; Bewley and Black 1994). Water-soluble phenolic compounds reduce germination by inhibiting the activities of peroxidases and the oxidation of other phenolics, processes that are indispensable for breaking the hard seed coat and promote the emergence of the seedling in Triticum aestivum (Kong et al 2008). Moreover, the low t50 differences among the genotypes after sulphuric acid-treatment (Table 4), confirm that acid treatment destroys the structure of the seed coat, thus allowing water imbibition (Nikolaeva 1977;Aliero 2004) and a uniform germination whatever the hardiness of the seed coat.…”

“…In the present experiment, to clarify the mechanisms of seed dormancy, the effects of hot water and sulphuric acid soaking on carob seed germination were explored. Polyphenols have been recognized as components of the leguminous seed coat having a good water solubility and capability to inhibit germination in some other species (Kong et al 2008;Inácio et al 2013). Therefore, total polyphenols leaching after hot water soaking was examined since this treatment does not determine the piercing (as mechanical scarification), nor the complete removal of all the constituents of the seed coat (as sulphuric acid treatment).…”

Pre-harvest sprouting resistance and haplotype variation of ThVp-1 gene in the collection of wheat-wheatgrass hybrids

“…Four entries (237, 1375, 1654, 1451) differ from others by rough glumes, which adhere very closely to the grain. This feature significantly hardens the process of threshing, and, on the other hand, contributes to the delay of water uptake [ 40 , 95 ].…”

The association between the allelic state of <i>Vp</i>-1<i>B</i> and pre-harvest sprouting tolerance in red-seeded hexaploid triticale

“…The color of seed in wheat and rye is determined by the accumulation of the phenolic products of the flavonoid pathway. The polyphenolic compounds are shown to be the inhibitors of germination [24,25]. The product of the Vp gene responsible for the embryo sensitivity to ABA, embryo maturation and its transition to dormancy [26] is also known to be involved in the flavonoid pathway [27].…”