Abscisic acid, polyamines and phenolic acids in sessile oak somatic embryos in relation to their conversion potential

Abstract

Two types of sessile oak ( Quercus petraea (Matt) Liebl.) somatic embryos with well-developed ivory or green-coloured cotyledons and root apices differing in their development, i.e. in the conversion into plantlets, were examined for the endogenous contents of abscisic acid (ABA), polyamines (PAs), aromatic monoamines (AMs), phenolic acids (PhAs), lignin and peroxidase activity. The conversion did not occur in embryos with deep green cotyledons (NCE, nonconverting embryos) while almost 56 % of embryos with ivory or light green cotyledons converted into plantlets (CE, converting embryos). High conversion capacity is associated with ( a) lower content of ABA, ( b) lower levels of free putrescine and its soluble conjugates, and higher content of spermidine soluble conjugates, ( c) markedly increased level of phenylethylamine and its soluble conjugates, and ( d) significantly lower content of total PhAs represented by the sum of free, soluble ester- and glycoside-, and insoluble cell wall-bound PhAs as compared to the contents in NCE. Higher levels of all determined free PhAs, and ten and three times higher contents of sinapic acid esters and glycosides, were found in NCE. On the contrary, three times higher ferulic acid content was found in the cell walls of CE. Higher content of lignin in NCE positively correlated with the amount of soluble phenolics and ionically bound peroxidase activity (EC 1.11.1.7). The results indicate that the alterations in phenylpropanoid metabolism in sessile oak somatic embryos are closely related to their developmental capability.