Open Access
Plant ammonium sensitivity is associated with external pH adaptation, repertoire of nitrogen transporters, and nitrogen requirement
(Oxford University Press, 2024-03-11) Rivero Marcos, Mikel; Lasa Larrea, Berta; Neves, Tomé; Zamarreño, Ángel M.; García Mina, José M.; García Olaverri, Carmen; Aparicio Tejo, Pedro María; Cruz, Cristina; Ariz Arnedo, Idoia; Ciencias; Zientziak; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Multidisciplinary Research in Applied Biology - IMAB; Institute for Advanced Research in Business and Economics - INARBE; Universidad Publica de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
Modern crops exhibit diverse sensitivities to ammonium as the primary nitrogen source, influenced by environmental factors such as external pH and nutrient availability. Despite its significance, there is currently no systematic classification of plant species based on their ammonium sensitivity. We conducted a meta-analysis of 50 plant species and present a new classification method based on the comparison of fresh biomass obtained under ammonium and nitrate nutrition. The classification uses the natural logarithm of the biomass ratio as the size effect indicator of ammonium sensitivity. This numerical parameter is associated with critical factors for nitrogen demand and form preference, such as Ellenberg indicators and the repertoire of nitrogen transporters for ammonium and nitrate uptake. Finally, a comparative analysis of the developmental and metabolic responses, including hormonal balance, is conducted in two species with divergent ammonium sensitivity values in the classification. Results indicate that nitrate has a key role in counteracting ammonium toxicity in species with a higher abundance of genes encoding NRT2-type proteins and fewer of those encoding the AMT2-type proteins. Additionally, the study demonstrates the reliability of the phytohormone balance and methylglyoxal content as indicators for anticipating ammonium toxicity. This study emphasizes the importance of ecophysiological requirements and the repertoire of nitrogen transporters in understanding plant sensitivity to ammonium, and enhances our knowledge of plant nitrogen nutrition.
Open Access
Foliar application of urea to "Sauvignon Blanc" and "Merlot" vines: doses and time of application
(Springer Nature, 2012-02-19) Lasa Larrea, Berta; Menéndez Villanueva, Sergio; Sagastizabal, Kepa; Calleja Cervantes, María Eréndira; Irigoyen Iriarte, Ignacio; Muro Erreguerena, Julio; Aparicio Tejo, Pedro María; Ariz Arnedo, Idoia; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Producción Agraria; Nekazaritza Ekoizpena
A careful control of the N nutritional status of grapevines can have a determining effect on wine characteristics; therefore a suitable management of N fertilization might allow some wine parameters to be modified, thereby improving product quality. The aim of this study was to determine the effect of foliar application of urea at different doses and different times of the growing season on the parameters of Sauvignon Blanc and Merlot grape juice. The research described herein involved Sauvignon Blanc and Merlot grapevines (V. vinifera L.) at a commercial vineyard and was conducted over 2 years. In the first year, N treatment involved a foliar application at a dose of 10 kg N ha−1 during veraison, whereas in the second year it involved a foliar urea application at two doses (10 and 50 kg N ha−1) and at three different times—3 weeks before veraison, during veraison and 3 weeks after veraison. In this second year, the urea applied at a dose of 10 kg N ha−1 was isotopically labelled with 1% 15N. Chemical parameters, yeast assimilable N, amino acid content, amino acid profile and N isotopic composition were determined for all treatments. Grape and grape-juice parameters for Merlot were found to be more affected by N fertilization than for Sauvignon Blanc and were also more affected during the second year than during the first year, thus indicating that the climatic characteristics of each campaign could affect these parameters. The yeast assimilable N in grape juice was found to be higher for late applications of foliar urea, with application of the higher dose of urea during veraison increasing the amino acid and proline contents in both varieties. The isotopic analysis data showed that the urea applied to leaves was transferred to the berries, with the maximum translocation in Sauvignon Blanc occurring for the post-veraison treatment and in Merlot for the veraison treatment. We can therefore conclude that foliar application of urea could modify grape juice quality and could therefore be used as a tool for obtaining quality wines.
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
Quantitative proteomics reveals the importance of nitrogen source to control glucosinolate metabolism in Arabidopsis thaliana and Brassica oleracea
(Oxford University Press, 2016) Marino Bilbao, Daniel; Ariz Arnedo, Idoia; Lasa Larrea, Berta; Santamaría Martínez, Enrique; Aparicio Tejo, Pedro María; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Accessing different nitrogen (N) sources involves a profound adaptation of plant metabolism. In this study, a quantitative proteomic approach was used to further understand how the model plant Arabidopsis thaliana adjusts to different N sources when grown exclusively under nitrate or ammonium nutrition. Proteome data evidenced that glucosinolate metabolism was differentially regulated by the N source and that both TGG1 and TGG2 myrosinases were more abundant under ammonium nutrition, which is generally considered to be a stressful situation. Moreover, Arabidopsis plants displayed glucosinolate accumulation and induced myrosinase activity under ammonium nutrition. Interestingly, these results were also confirmed in the economically important crop broccoli (Brassica oleracea var. italica). Moreover, these metabolic changes were correlated in Arabidopsis with the differential expression of genes from the aliphatic glucosinolate metabolic pathway. This study underlines the importance of nitrogen nutrition and the potential of using ammonium as the N source in order to stimulate glucosinolate metabolism, which may have important applications not only in terms of reducing pesticide use, but also for increasing plants’ nutritional value.
Open Access
Short term physiological implications of NBPT application on the N metabolism of Pisum sativum and Spinacea oleracea
(Elsevier, 2011-03-01) Cruchaga Moso, Saioa; Artola Rezola, Ekhiñe; Lasa Larrea, Berta; Ariz Arnedo, Idoia; Irigoyen Iriarte, Ignacio; Morán Juez, José Fernando; Aparicio Tejo, Pedro María; Ciencias del Medio Natural; Natura Ingurunearen Zientziak; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Producción Agraria; Nekazaritza Ekoizpena
The application of urease inhibitors in conjunction with urea fertilizers as a means of reducing N loss due to ammonia volatilization requires an in-depth study of the physiological effects of these inhibitors on plants. The aim of this study was to determine how the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) affects N metabolism in pea and spinach. Plants were cultivated in pure hydroponic culture with urea as the sole N source. After 2 weeks of growth for pea, and 3 weeks for spinach, half of the plants received NBPT in their nutrient solution. Urease activity, urea and ammonium content, free amino acid composition and soluble protein were determined in leaves and roots at days 0, 1, 2, 4, 7 and 9, and the NBPT content in these tissues was determined 48 h after inhibitor application. The results suggest that the effects of NBPT on spinach and pea urease activity differ, with pea being most affected by this treatment, and that the NBPT absorbed by the plant caused a clear inhibition of the urease activity in pea leaf and roots. The high urea concentration observed in leaves was associated with the development of necrotic leaf margins, and was further evidence of NBPT inhibition in these plants. A decrease in the ammonium content in roots, where N assimilation mainly takes place, was also observed. Consequently, total amino acid contents were drastically reduced upon NBPT treatment, indicating a strong alteration of the N metabolism. Furthermore, the amino acid profile showed that amidic amino acids were major components of the reduced pool of amino acids. In contrast, NBPT was absorbed to a much lesser degree by spinach plants than pea plants (35% less) and did not produce a clear inhibition of urease activity in this species.