Abstract
ABSTRACT Three rice (Oryza sativa L.) varieties: Caiapó (bred for upland crop), Piauí (a landrace), and IAC-47 (an improved variety) were used to study the effects of nitrogen (N) suppression in plant metabolism. Nitrogen suppression increased root growth in Caiapó plants. This growth was simultaneous with increases in hydrogen (H+)-pyrophosphatase (H+-PPase) and vacuolar H+-ATPase (V-H+-ATPase) activities in the roots of Piauí plants. The SDS-PAGE shows 73, 67, and 53 kDa fractions proteins accumulating in the tonoplast what agrees with the observed activities of H+-PPases and V-H+-ATPases. Piauí and IAC-47 varieties exhibited different responses from one another at the beginning of N-Stress: there was an increase in P-H+-ATPase activity for Piauí and a decrease for IAC-47. Piauí plants had a higher content of nitrate (NO3 −) in roots and sheaths, notwithstanding it mobilized less of this NO3 −-N during this growth period than did IAC-47. These results suggest that Piauí plants are better adapted to nutrient-poor environments.
Published Version
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