Cellular responses of two Latin-American cultivars of Lotus corniculatus to low pH and Al stress

Abstract

Toxic effects of acidic root medium and aluminium were evaluated in two forage cultivars of Lotus corniculatus differing in their tolerance to Al stress. The structural response of most of the root cells exposed to low pH without Al 3+ differed markedly from that induced by the combined stress. Conspicuous alteration of the nucleus was present only at low pH 4.0 and disintegration of the cytoplasmic components was more drastic than in the roots exposed to acidic solution containing Al 3+ . Cells exposed to low pH without Al, did not produce wall thickenings. Severely damaged cytoplasm and localized death in some cortical cells or groups of cells contrasting with almost intact cells exposed to Al 3+ stress were found. In this respect, a strong correlation between the occurrence of cell wall thickenings and a better preserved structure of the cytoplasm was observed. The frequency of cell damage in the more tolerant cultivar UFRGS was generally lower, significantly more cortical cells capable of maintaining their resting membrane potential were present than in the sensitive INIA Draco. The difference in their tolerance is related rather to the exudation of citrate and oxalate that was higher in UFRGS than to the accumulation of tannins, which increased after Al treatment in both cultivars.

Unraveling Morphophysiological and Biochemical Responses of <em>Triticum aestivum </em>L. to Extreme pH: Coordinated Actions of Antioxidant Defense and Glyoxalase Systems

“…overgeneration of ROS (O2 •− , H2O2, OH • ). In line with other abiotic stress factors, under extreme pH, both acidic and alkaline-stress, we observed elevated lipid peroxidation (measured as MDA), H2O2 overgeneration and increased LOX activity in the leaf tissue of wheat seedlings, which keep in with other studies [11,13,27,28]. Alkali stress induced greater cellular structural damage and higher lipid peroxidation was found in tomato plants [27].…”

“…Yet, ionic imbalance and disturbance in pH homeostasis within plant tissue under alkalinity-stress cause the precipitation of metal ions, consequently responsible for photosynthetic pigments breakdown and subsequent leaf chlorosis, reduced photosynthetic rate and consequently stunted growth [9] . Similar, decreased photochemical efficiency, chl and car content were reported also under higher pH (alkali stress) in Cucumis sativus, Medicago sativa, and O. sativa [28]. Thus, this reduction in photosynthesis leads to lower biomass accumulation.…”

“…Similarly, acidic stress (pH 4.5) induced lipid peroxidation (higher MDA content) was also observed in H. vulgare seedlings [11]. Parallel, rising ROS content and lipid peroxidation was also found in P. sylvestris and Lotus corniculatus, Oryza sativa and citrus following exposure towards acidity [13,28,29,30].…”

Regulation of gene expression in roots of the pH-sensitive Vaccinium corymbosum and the pH-tolerant Vaccinium arboreum in response to near neutral pH stress using RNA-Seq

“…Furthermore, acidification of the cytoplasm of plants grown in acidic conditions leads to accumulation of reactive oxygen species (ROS) and subsequent activation of antioxidative mechanisms in the roots [ 20 , 21 ]. Oxidative damage is likely to be responsible for the damage to root epidermal cells observed in non-calcifuge plants grown in acidic soils and media [ 22 ].…”

Physiological, Biochemical and Microstructural Changes in Rice (Oryza sativaL.) under Varying pH Levels

“…Plants exposed to strong acidic conditions have enormous impact on root cell structures and its functions [7,8]. At pH 4.0, legume Lotus corniculatus suffered significant damage in the epidermal and cortical cells of roots and depolarized membranes [9,10]. Reduced root elongations, swollen root hairs and cracks between root meristem region and damaged plasma membranes were observed in arabidopsis [11], alfalfa [12], spinach [13], common bean [14], and barley [15] under acidic stress conditions.…”