Free Amino Acids in Vegetative Organs of Picea obovata L. and Pinus sylvestris L.

Аннотация

It was shown that the changes in the phenological stages of tree development, associated with the loss of frost resistance and the onset of the growing season, were accompanied by significant changes in free amino acid composition in the meristematic tissues of Picea obovata L. and Pinus sylvestris L. buds. In winter, in both species, the level of nonproteingeneous amino acids was doubled in comparison with spring. At the same time, P. obovata and P. sylvestris showed significant species-specific differences in the total content of nonproteaginous amino acids. At P. sylvestris their share in the composition of free amino acids reached 40%, which was twice as high as that of P. obovata. In the free amino acids in P. obovata and P. sylvestris, the nitrogen reserve was mainly in the form of glycine corresponding to 13 and 9%, arginine, 12 and 8%, and ornithine, 12 and 15%, respectively. In addition, in P. sylvestris an important role in the nitrogen storage was played by γ- aminobutyric acid, about 19%, and valine, about 6%; in P. obovata this role was played by lysine and glutamic acid, about 10%. At the same time, the content of proline (an amino acid, which, generally, coordinates the high−low-temperature resistance of plants) in low-resistance coniferous species was low at about 0.04–0.34%. In spring, with bud swelling in both species, the share of arginine and proline increased, and the share of ornithine and γ-aminobutyric acid sharply decreased. In addition to these amino acids, the lysine content in P. obovata was doubled. In spring, for P. sylvestris a high content of aspartic acid and asparagine of about 19% was characteristic, for P. obovata the content of amino acids with a short carbon chain (the total amount of serine + glycine) rose to 22%. As a reliable stress metabolite in both species, one may consider ornithine, whose content in bud meristems in winter was 3–5 times higher than in the meristems of swollen buds in spring.