Open Access
Ecophysiological roles of abaxial anthocyanins in a perennial understorey herb from temperate deciduous forests
(Oxford University Press, 2015) Fernández Marín, Beatriz; Esteban Terradillos, Raquel; Míguez, Fátima; Artetxe, Unai; Castañeda Presa, Verónica; Pintó Marijuan, Marta; Becerril, José María; García Plazaola, José Ignacio; Natura Ingurunearen Zientziak; Ciencias del Medio Natural; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
Accumulation of abaxial anthocyanins is an intriguing leaf trait particularly common among deeply shaded understorey plants of tropical and temperate forests whose ecological significance is still not properly understood. To shed light on it, possible ecophysiological roles of abaxial anthocyanins were tested in the perennial understorey herb of temperate deciduous forests Saxifraga hirsuta, chosen as a model species due to the coexistence of green and anthocyanic leaves and the presence of an easily removable lower anthocyanic epidermis. Anthocyanins accumulated during autumn, which temporally matched the overstorey leaf fall. Patterns of development of abaxial anthocyanins and direct measurements of photochemical efficiency under monochromatic light were not consistent with a photoprotective hypothesis. Enhancement of light capture also seemed unlikely since the back-scattering of red light towards the lower mesophyll was negligible. Seed germination was similar under acyanic and anthocyanic leaves. A relevant consequence of abaxial anthocyanins was the dramatic reduction of light transmission through the leaf. The dark environment generated underneath the Saxifraga canopy was enhanced by the horizontal repositioning of leaves, which occurs in parallel with reddening. This might play a role in biotic interactions by inhibiting vital processes of competitors, which may be of especial importance in spring before the overstorey leaves sprout.
Open Access
Functional analysis of the taproot and fibrous roots of Medicago truncatula: sucrose and proline catabolism primary response to water deficit
(Elsevier, 2019) Castañeda Presa, Verónica; Peña, Marlon de la; Azcárate Górriz, Lidia; Aranjuelo Michelena, Iker; González García, Esther; Ciencias; Zientziak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Root performance represents a target factor conditioning plant development under drought conditions. Moreover, recent root phenotyping studies remark relevant differences on functionality of the different root types. However, despite its relevance, the performance of different types of roots such as primary/taproot (tapR) and lateral/fibrous roots (fibR) under water stress conditions is largely unknown. In the current study, the impact of water stress on target C and N metabolism (namely sucrose and proline) processes were characterized in tapR and fibR of Medicago truncatula plants exposed to different water stress severity regimes (moderate versus severe). While both root types exhibit some common responses to face water stress, the study highlighted important physiological and metabolic differences between them. The tapR proved to have an essential role on carbon and nitrogen partitioning rather than just on storage. Moreover, this root type showed a higher resilience towards water deficit stress. Sucrose metabolization at sucrose synthase level was early blocked in this tissue together with a selective accumulation of some amino acids such as proline and branched chain amino adds, which may act as alternative carbon sources under water deficit stress conditions. The decline in respiration, despite the over-accumulation of carbon compounds, suggests a modulation at sucrose cleavage level by sucrose synthase and invertase. These data not only provide new information on the carbon and nitrogen metabolism modulation upon water deficit stress but also on the different role, physiology, and metabolism of the taproot and fibrous roots. In addition, obtained results highlight the fact that both root types show distinct performance under water deficit stress; this factor can be of great relevance to improve breeding programs for increasing root efficiency under adverse conditions.
Open Access
Legume nitrogen utilization under drought stress
(Springer, 2018) Castañeda Presa, Verónica; Gil Quintana, Erena; Echeverría Obanos, Andrés; González García, Esther; Ciencias; Zientziak
Legumes account for around 27% of the world’s primary crop production and can be classified based on their use and traits into grain and forage legumes. Legumes can establish symbiosis with N-fixing soil bacteria. As a result, a new organ is formed, the nodule, where the reduction of atmospheric N2 into ammonia is carried out catalyzed by the bacterial exclusive enzyme nitrogenase. The process, highly energy demanding, is known as symbiotic nitrogen fixation and provides all the N needs of the plant, thus avoiding the use of N fertilizers in the context of sustainable agriculture. However, legume crops are often grown under non-fixing conditions since legume nodulation is suppressed by high levels of soil nitrogen occurring in chemically fertilized agro-environment. In addition, legumes are very sensitive to environmental stresses, being drought one of the significant constraints affecting crop production. Due to their agricultural and economic importance, scientists have carried out basic and applied research on legumes to better understand responses to abiotic stresses and to further comprehend plant–microbe interactions. An integrated view of nitrogen utilization under drought stress will be presented with particular focus on legume crops.

Castañeda Presa, Verónica

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