Open Access
The physiological implications of urease inhibitors on N metabolism during germination of Pisum sativum and Spinacea oleracea seeds
(Elsevier, 2012-03-08) Ariz Arnedo, Idoia; Cruchaga Moso, Saioa; Lasa Larrea, Berta; Morán Juez, José Fernando; Jáuregui Mosquera, Iván; Aparicio Tejo, Pedro María; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
The development of new nitrogen fertilizers is necessary to optimize crop production whilst improving the environmental aspects arising from the use of nitrogenous fertilization as a cultural practice. The use of urease inhibitors aims to improve the efficiency of urea as a nitrogen fertilizer by preventing its loss from the soil as ammonia. However, although the action of urease inhibitors is aimed at the urease activity in soil, their availability for the plant may affect its urease activity. The aim of this work was therefore to evaluate the effect of two urease inhibitors, namely acetohydroxamic acid (AHA) and N-(n-butyl) thiophosphoric triamide (NBPT), on the germination of pea and spinach seeds. The results obtained show that urease inhibitors do not affect the germination process to any significant degree, with the only process affected being imbibition in spinach, thus also suggesting different urease activities for both plants. Our findings therefore suggest an activity other than the previously reported urolytic activity for urease in spinach. Furthermore, of the two inhibitors tested, NBPT was found to be the most effective at inhibiting urease activity, especially in pea seedlings.
Open Access
Unravelling the mechanisms that improve photosynthetic performance of N₂-fixing pea plants exposed to elevated [CO₂]
(Elsevier, 2014) Aranjuelo Michelena, Iker; Cabrerizo Geijo, Pablo María; Aparicio Tejo, Pedro María; Arrese-Igor Sánchez, César; Natura Ingurunearen Zientziak; Ciencias del Medio Natural; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
Although the predicted enhanced photosynthetic rates of plants exposed to elevated [CO₂] are expected to increase carbohydrate and plant growth, recent findings have shown a complex regulation of these processes. The aim of this study was to determine the effect of elevated [CO₂] on pathways leading to the main forms of leaf C storage (starch) and export (sucrose) and the implications of this increased [CO₂] on photosynthetic performance of exclusively N2 fixing plants. For this purpose, exclusively N2-fixing pea plants were exposed to elevated [CO₂] (1000 mol mol−1 versus 360 mol mol−1 CO₂). The data obtained highlighted that plants exposed to elevated [CO₂] were capable of maintaining hexose levels (involved in Rubisco down regulation) at control levels with the consequent avoidance of photosynthetic acclimation. More specifically, in plants exposed to elevated [CO₂] there was an increase in the activity of pathways involved in the main forms of leaf C storage (starch) and export (sucrose). Furthermore, the study highlighted that although starch content increased by up to 40% under elevated [CO₂], there was also an increase in the proteins and compounds involved in starch degradation. Such a finding, together with an increase in the activity of proteins involved in sucrose synthesis revealed that these plants up-regulated the sucrose synthesis pathway in order to meet the large nodule photoassimilate requirements. As a consequence, the study highlighted the relevance of controlling the activity of pathways that determine leaf cellular carbohydrate availability and how this is linked with C-demanding organs such as nodules.

Aparicio Tejo, Pedro María

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