IFEVA   02662
INSTITUTO DE INVESTIGACIONES FISIOLOGICAS Y ECOLOGICAS VINCULADAS A LA AGRICULTURA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Root growth under anaerobic conditions as affected by radial oxygen loss and root cortical traits in two species of the Flooding Pampa Grasslands (Argentina).
Autor/es:
MANZUR MILENA ELISA; GRIMOLDI AGUSTÍN ALBERTO; INSAUSTI PEDRO; STRIKER GUSTAVO GABRIEL
Lugar:
Columbus, Ohio, EEUU
Reunión:
Congreso; International Conference Plant Vascular Biology 2010; 2010
Institución organizadora:
Ohio State University
Resumen:
The anoxic environment associated with flooding induces a sequence of plant changes that comprise physiological, anatomical and morphological adjustments related to their survival under anaerobic conditions. The most common responses include adventitious rooting along with increases in aerenchyma tissue, which facilitate root aeration by providing a low resistance pathway to oxygen diffusion from aerial shoots to submerged roots. However, root growth under anaerobic conditions could be constrained due to the reduced apex oxygenation, which in turn could depend on the amount of radial oxygen loss from the roots toward the rhizosphere (hereafter ROL). The aim of this work was to investigate the anatomical traits and physiological responses defining the adventitious root growth under aerobic and anaerobic conditions of two species with contrasting types of aerenchyma of the Flooding Pampa Grasslands of Argentina: the graminoid Cyperus eragrostis (“spiderweb” aerenchyma) and the dicotyledonous Rumex crispus (“honeycomb” aerenchyma). Plants of both species were grown under hydroponics culture (half-strength Hoagland nutrient solution) under two treatments: aerated (7.9 mg.O2.L-1) and stagnant (0.5 mg.O2.L-1). We assessed the proportion of aerenchyma tissue, the pattern of ROL along roots (0.5, 1, 2, 3, 4 and 5 cm from the apex), suberin deposition in the cells of the outer cortex by UV fluorescence, root growth rate and final root length. Results showed that the proportion of aerenchyma tissue was higher under anaerobic than aerobic conditions for both species (54.1% vs. 18.1% in R. crispus and 38.5% vs. 16.9% in C. eragrostis). In R. crispus, ROL was similar between treatments (136 vs. 127 ng.cm-2.min-1; p=0.68) without differences along the root. By contrast, C. eragrostis showed a differential ROL pattern along the root, being higher near the apex than towards the root base. Interestingly, anaerobic conditions determined a ROL reduction at root basal positions (106 vs. 44 ng.cm-2.min-1), suggesting the induction of a “ROL barrier” in response to anoxia as the higher fluorescence intensity measurements revealed. The root growth rate and final root length of R. crispus was lower under anaerobic than under aerobic conditions (25.2% and 54.3%, respectively; p=0.02), while root growth of C. eragrostis was not affected by anaerobic conditions (p=0.9). In conclusion, although both species noticeably increased root aerenchyma under anoxia, the ability of the graminoid C. eragrostis in generating a “ROL barrier” seems to bring an advantage for maintaining root growth and soil exploration under anaerobic conditions.