Inside issues, all of our performance support partly the fresh theory away from Vid ) one to Gln could be the main off-regulator off nitrate consumption and a putative much time-distance inter-organ laws from inside the planta ( Nazoa et al. 2003 ).
Inside our studies, a positive effect of GABA into nitrate use is certainly shown from the exogenous also have in order to origins on transcriptional (Fig
However, three main results of the present growth cycle experiment provide evidence which contradicts the hypothesis of N uptake down-regulation by total amino acids or Gln content: (i) the high content of total amino acids recorded in phloem exudates during the bolting period when N uptake increases (1, 2), which is not consistent with a main role of amino acids in down-regulation of nitrate uptake; (ii) the lack of nitrate uptake ‘de-repression’ at the beginning of pod filling (G2 stage) when total amino acid content in the phloem exudate was at its lowest value (1, 2); (iii) the lack of a significant correlation between 15 NO3 – influx www.datingranking.net/local-hookup/nanaimo/ and relative Gln contribution in the phloem exudate (r 2 = 0.44, P > 0.05; Fig. 4d). These results must, however, be interpreted with caution. The dual role of some amino acids, both as nutrients and as signals, and their possible interconversion or compartmentalization in root tissues is potentially problematic in phloem sap analysis when attempting to correlate influx variations with amino acid composition. (more…)