Citrulline was the major amino acid in root pressure sap, stem sap and stem wood from Alnus glutinosa L. Gaertn. plants relying on fixed nitrogen or, partly or wholly, on mineral nitrogen for growth. Glutamine increased in prominence in plants assimilating mineral nitrogen but asparagine remained a relatively insignificant component. Differences in the relative amounts of the free amino compounds of stem sap from nitrogen‐fixing and mineral nitrogen‐fed plants were usually small compared to differences between plants fed different sources of mineral nitrogen. In contrast, relatively high values for the ratios of citrulline/total free amino nitrogen compounds and particularly of citrulline/amides in root pressure sap distinguished nitrogen‐fixing plants from those receiving mineral nitrogen. Although the amino acid ratios of stem wood extracts showed closer similarity to those for root pressure sap than stem sap, the seasonal accumulation of citrulline, possibly as a storage amino acid, in stem wood from field‐grown plants negated the possibility of utilising stem wood analyses as an indicator of the form of nitrogen assimilation. Comparative data on the levels of citrulline or other free amino acids in Alnus glutinosa are unlikely to be useful as an index of nitrogen fixation, under most experimental conditions.
Sintomas de deficiência de macronutrientes foram induzidos na soja, var. IAC-2. Foi verificado o efeito da omissão de N, R, K, Ca, Mg e S no crescimento, produção e composição mineral das folhas.
1990. Effect of nitrogen nutrition on amino acid composition of xylem sap and stem wood in Alnus glutinosa. -Physiol. Plant. 79; 506-511.Citrulline was the major amino acid in root pressure sap, stem sap and stem wood from Alnus glutinosa L. Gaertn. plants relying on fixed nitrogen or, partly or wholly, on mineral nitrogen for growth. Glutamine increased in prominence in plants assinnilating mineral nitrogen but asparagine remained a relatively insignificant component. Differences in the relative amounts of the free amino compounds of stem sap from nitrogen-fixing and mineral nitrogen-fed plants were usually small compared to differences between plants fed different sources of mineral nitrogen. In contrast, relatively high values for the ratios of citrulline/total free amino nitrogen compounds and particularly of citrulline/amides in root pressure sap distinguished nitrogen-fixing plants from those receiving mineral nitrogen. Although the amino acid ratios of stem wood extracts showed closer similarity to those for root pressure sap than stem sap, the seasonal accumulation of citrulline, possibly as a storage amino acid, in stem wood from field-grown plants negated the possibility of utihsing stem wood analyses as an indicator of the form of nitrogen assimilation. Comparative data on the levels of citrulline or other free amino adds in Alnus glutinosa are unlikely to be useful as an index of nitrogen fixation, under most experimental conditions.
Abstract. The principal polyamines in Alnus glutinosa roots, nodules and root pressure sap, putrescine, spermidine and spermine, were quantified by reversed‐phase, high‐performance liquid chromatography with fluorescence detection following precolumn derivatization with 9‐fluorenylmethyl chloroformate and 1‐ada‐mantanamine. Putrescine was the major component of all tissues and sap. It comprised 70% or more of the polyamine pool except in roots of KNO3‐fed plants, in which similar amounts of putrescine and spermidine were present at levels five‐fold lower than plants fed (NH4)2SO4. Polyamine levels in nodules were 50% greater than in roots. The polyamine content of roots and nodules was not altered significantly when the nitrogen nutrition was changed from sole reliance on nitrogen fixation to partial or complete utilization of (NH4)2SO4. However, the polyamine content of root pressure sap from nodulated plants increased almost four‐fold when they were fed with increasing concentrations of NH4NO3, although the total polyamine content remained low (5mmol m−3 sap). The polyamine content of the Alnus root system changed with plant age. In particular, the spermidine content of both roots and nodules was higher in 10‐ as compared to 16‐week‐old plants.
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