Biotemas (Nov 2013)
Allocation of reserve nitrogen compounds during germination of Canavalia brasiliensis seeds
Abstract
Canavalia brasiliensis, commonly known as “feijão-bravo-do-ceará”, is an herbaceous plant with a great potential for biomass production and rusticity within the period of low water availability, coupled with the great effectiveness of nitrogen fixation. This article aims to evaluate the main nitrogen compounds and their translocation from seed to seedling during and after germination. For this, the experiment was conducted in a germination chamber, and seedlings were kept in 4 L pots containing vermiculite throughout the experimental period. Seedlings were collected every 2 days until the senescence and abscission of cotyledons, which took place 16 days after germination (radicle protrusion). In each of the collection times, we divided seedlings into roots, stem, leaves, and cotyledons and analyzed, three times, the total protein, total soluble amino acids, canavanine, ureides (allantoin and allantoic acid), and nitrate contents in all tissues. We observed a decrease in the canavanine and total protein levels as the collection period was increased, and the canavanine levels disappeared after 16 days. Proteins and amino acids showed inversely proportional concentrations, i.e. whenever one increases the other decreases until the senescence and abscission of cotyledons. We detected the presence of nitrate in the seedling tissues until the last collection (16 days after germination). The concentration of ureides (allantoic acid and allantoin) was high throughout the evaluated period, indicating that they are compounds for nitrogen metabolism in C. brasiliensis, and there is de novo synthesis.
