1,721,198 research outputs found
Molecular and physiological interactions of urea and nitrate uptake in plants
No full textWhile nitrate acquisition has been extensively studied, less information is available on transport systems of urea. Furthermore, the reciprocal influence of the two sources has not been clarified, so far. In this review, we will discuss recent developments on plant response to urea and nitrate nutrition. Experimental evidence suggests that, when urea and nitrate are available in the external solution, the induction of the uptake systems of each nitrogen source is limited, while plant growth and N utilization is promoted. This physiological behavior might reflect cooperation among acquisition processes, where the activation of different N assimilatory pathways (cytosolic and plastidic pathways), allowing a better control on the nutrient uptake. Based on physiological and molecular evidence, plants might increase nitrogen metabolism promoting a more efficient assimilation of taken-up nitrogen. The beneficial effect of urea and nitrate nutrition might contribute to develop new agronomical approaches to increase the nitrogen use efficiency in crops
Measurement of net high-affinity urea uptake in maize plants
No full textDespite its extensive use as a nitrogen fertilizer, the role of urea as a directly accessible nitrogen source for crop plants is still poorly understood. So far, the physiological and molecular aspects of urea acquisition have been investigated only in a few plant species highlighting the importance of a urea transporter in roots, DUR3 (Kojima et al., 2007; Wang et al., 2012; Zanin et al., 2014a). Regarding maize plants, a crop that needs a large amount of urea fertilizer, the capability to take up urea via an inducible and high-affinity transport system has been recently characterized (Zanin et al., 2014a; Zanin et al., 2014b). Here, we described a small-scale protocol suitable for the measurement of urea net high-affinity uptake in roots of intact maize plants
Caratterizzazione fisiologica e molecolare del rilascio di essudati radicali in piante di melo sottoposte a stress nutrizionali
No full textEffetto della disponibilità di zolfo sull’assorbimento di nitrato e di solfato in barbatelle di vite allevate in soluzione idroponica
No full textSucrose accumulation in developing peach fruit
No full textUptake of C-14-sugars and activities of sucrose metabolizing enzymes were determined in order to study the mechanism(s) of sucrose accumulation in developing peach fruit. Mesocarp of young peach fruit contained glucose and fructose but little sucrose. Starting 88 days after anthesis (DAA) the sucrose concentration increased greatly. The mechanism of sucrose accumulation was studied by measuring C-14-sucrose and C-14-glucose uptake rates at three different stages of fruit development, and by assaying weekly the activity of enzymes involved in the hydrolysis and/or synthesis of the soluble sugars. Uptake of 0.5-100 mM C-14-sucrose and C-14-glucose by mesocarp tissue slices showed a complex pattern at the first stage of fruit development (62 DAA). During the subsequent growth stages the pattern of sugar uptake changed and was approximately monophasic at the third stage of fruit development.
At 10 mM, glucose was taken up more rapidly than sucrose at the first and second stage of fruit development. Uptake was partially inhibited by the uncoupler carbonyl-cyanide m-chlorophenylhydrazone (CCCP) at 25 mu M. These results, together with the presence of a putative extracellular invertase, suggest an apoplastic route for sucrose uptake which is dependent, at least in part, on energy supply.
Activities of sucrose hydrolyzing enzymes (insoluble acid invertase, soluble acid invertase, neutral invertase, sucrose synthase) were high in young fruits and declined sharply with fruit development concomitantly with accumulation of sucrose. The storage of the sugar was not accompanied by a rise in synthetic activities (sucrose synthase, sucrose phosphate synthase), suggesting that sucrose could, at least in part enter the carbohydrate pool directly
Involvement of two MATE genes in the release of root exudates in apple plants grown under nutrient deficiency
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