Sanz-Saez, A. (Álvaro)
- Publications
- item.page.relationships.isContributorAdvisorOfPublication
- item.page.relationships.isContributorOfPublication
3 results
Search Results
Now showing 1 - 3 of 3
- Photosynthesis, N2 fixation and taproot reserves during the cutting regrowth cycle of alfalfa under elevated CO2 and temperature(Elsevier, 2011) Sanz-Saez, A. (Álvaro); Aguirreolea, J. (Jone); Aranjuelo, I. (Iker); Sanchez-Diaz, M. (Manuel); Avice, J.C. (Jean-Christophe); Irigoyen, J.J. (Juan Jose); Erice, G. (Gorka)Future climatic conditions, including rising atmospheric CO2 and temperature may increase photosynthesis and, consequently, plant production. A larger knowledge of legume performance under the predicted growth conditions will be crucial for safeguarding crop management and extending the area under cultivation with these plants in the near future. N2fixation is a key process conditioning plant responsiveness to varying growth conditions. Moreover, it is likely to increase under future environments, due to the higher photosynthate availability, as a consequence of the higher growth rate underelevated CO2. However, as described in the literature, photosynthesis performance is frequently down-regulated (acclimated) under long-term exposure to CO2, especially when affected by stressful temperature and water availability conditions. As growth responses to elevated CO2 are dependent on sink-source status, it is generally accepted that down-regulation occurs in situations with insufficient plant C sink capacity. Alfalfa management involves the cutting of shoots, which alters the source–sink relationship and thus the photosynthetic behaviour. As the growth rate decreases at the end of the pre-cut vegetative growth period, nodulated alfalfa plants show photosynthetic down-regulation, but during regrowth following defoliation, acclimation to elevated CO2 disappears. The shoot harvest also leads to a drop in mineral N uptake and C translocation to the roots, resulting in a reduction in N2fixation due to the dependence on photosynthate supply to support nodule function. Therefore, the production of new shoots during the first days following cutting requires the utilization of reduced C and N compounds that have been stored previously in reserve organs. The stored reserves are mediated by phytohormones such as methyl jasmonate and abscisic acid and in situations where water stress reduces shoot production this potentially enables the enhancement of taproot protein levels in nodulated alfalfa, which may lead to these plants being in better condition in the following cut/regrowthcycle. Furthering our knowledge of legume performance under predicted climate change conditions will be crucial for the development of varieties with better adaptation that will achieve greater and more efficient production values. Furthermore, for this purpose it will be necessary to improve existing methodologies and create new ones for phenotype characterization. Such knowledge will provide key information for future plant breeding programs.
- Carbon balance, partitioning and photosynthetic acclimation in fruit-bearing grapevine (Vitis vinifera L. cv. Tempranillo) grown under simulated climate change (elevated CO2, elevated temperature and moderate drought) scenarios in temperature gradient(2015) Morales, F. (Fermin); Sanz-Saez, A. (Álvaro); Aguirreolea, J. (Jone); Araus, J.L. (José Luis); Aranjuelo, I. (Iker); Pascual-Elizalde, I. (Inmaculada); Sanchez-Diaz, M. (Manuel); Salazar-Parra, C. (Carolina); Irigoyen, J.J. (Juan Jose); Erice, G. (Gorka)Although plant performance under elevated CO2 has been extensively studied in the past little is known about photosynthetic performance changing simultaneously CO2, water availability and temperature conditions. Moreover, despite of its relevancy in crop responsiveness to elevated CO2 conditions, plant level C balance is a topic that, comparatively, has received little attention. In order to test responsiveness of grapevine photosynthetic apparatus to predicted climate change conditions, grapevine (Vitis vinifera L. cv. Tempranillo) fruit-bearing cuttings were exposed to different CO2 (elevated, 700 ppm vs. ambient, ca. 400 ppm), temperature (ambient vs. elevated, ambient +4 °C) and irrigation levels (partial vs. full irrigation). Carbon balance was followed monitoring net photosynthesis (AN, C gain), respiration (RD) and photorespiration (RL) (C losses). Modification of environment 13C isotopic composition (δ13C) under elevated CO2 (from −10.30 to −24.93‰) enabled the further characterization of C partitioning into roots, cuttings, shoots, petioles, leaves, rachides and berries. Irrespective of irrigation level and temperature, exposure to elevated CO2 induced photosynthetic acclimation of plants. C/N imbalance reflected the inability of plants grown at 700 ppm CO2 to develop strong C sinks. Partitioning of labeled C to storage organs (main stem and roots) did not avoid accumulation of labeled photoassimilates in leaves, affecting negatively Rubisco carboxylation activity. The study also revealed that, after 20 days of treatment, no oxidative damage to chlorophylls or carotenoids was observed, suggesting a protective role of CO2 either at current or elevated temperatures against the adverse effect of water stress.
- Photosynthetic down-regulation under elevated CO2 exposure can be prevented by nitrogen supply in nodulated alfalfa(Elsevier, 2010) Sanz-Saez, A. (Álvaro); Nogues, S. (Salvador); Aranjuelo, I. (Iker); Sanchez-Diaz, M. (Manuel); Irigoyen, J.J. (Juan Jose); Erice, G. (Gorka)Increasing atmospheric CO2 concentrations are expected to enhance plant photosynthesis and yield. Nevertheless, after long-term exposure, plants acclimate and show a reduction in photosynthetic activity (called down-regulation), which may cause a reduction in potential yield. Some authors suggest that down-regulation is related to nutrient availability, and more specifically, to an insufficient plant C sink strength caused by limited N supply. In this paper, we tested whether or not N availability prevents down-regulation of photosynthesis in nodulatedalfalfa plants (Medicago sativa L.). To do so, we examined the effect of the addition of different levels of NH4NO3 (0, 10, and 15 mM) to 30-day-old nodulatedalfalfa plants exposed to ambient (approximately 400 μmol mol−1) or elevated CO2 (700 μmol mol−1) during a period of 1 month in growth chambers. After 2 weeks of exposure to elevated CO2, no significant differences were observed in plant growth or photosynthesis rates. After 4 weeks of treatment, exclusively N2 fixing alfalfa plants (0 mM NH4NO3) showed significant decreases in photosynthesis and Vcmax. Photosyntheticdown-regulation of these plants was caused by the C/N imbalance as reflected by the carbohydrate and N data. On the other hand, plants supplied with 15 mM NH4NO3 grown underelevated CO2 maintained high photosynthetic rates owing to their superior C/N adjustment. The intermediate N treatment, 10 mM NH4NO3, also showed photosyntheticdown-regulation, but to a lesser degree than with 0 mM treatment. The present study clearly shows that external N supply can reduce or even avoid acclimation of photosynthesis to elevated CO2 as a consequence of the increase in C sink strength associated with N availability.