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

Functional Conservation and Divergence of Soybean GmSTOP1 Members in Proton and Aluminum Tolerance

Proton (H⁺) and aluminum (Al) rhizotoxicity are two major factors limiting crop production in acid soils. Orthologs of the zinc-finger transcription factor, Sensitive To Proton Rhizotoxicity1 (STOP1), have been found to play an essential role in the tolerance to both stresses by regulating the transcription of multiple H⁺ and Al tolerant genes. In the present study, color three GmSTOP1 homologs were identified in the soybean genome. All three GmSTOP1 exhibited similar properties as reflected by the harboring of four potential zinc finger domains, localizing in the nucleus, and having transactivation activity. Expression profiling showed that H⁺ stress slightly modulated transcription of all three GmSTOP1s, while Al significantly up-regulated GmSTOP1-1 and GmSTOP1-3 in root apexes and GmSTOP1-3 in basal root regions. Furthermore, complementation assays in an Arabidopsis Atstop1 mutant line overexpressing these GmSTOP1s demonstrated that all three GmSTOP1s largely reverse the H⁺ sensitivity of the Atstop1 mutant and restore the expression of genes involved in H⁺ tolerance. In contrast, only GmSTOP1-1 and GmSTOP1-3 could partially recover Al tolerance in the Atstop1 mutant. These results suggest that the function of three GmSTOP1s is evolutionarily conserved in H⁺ tolerance, but not in Al tolerance.

Aluminium Toxicity to Plants as Influenced by the Properties of the Root Growth Environment Affected by Other Co-Stressors: A Review

Aluminium toxicity to crops depends on the acidity of the soil and specific plant resistance. However, it is also strongly affected by other environmental factors that have to be considered to properly evaluate the resultant effects on plants. Observed weather perturbations and predicted climate changes will increase the probability of co-occurrence of aluminium toxicity and other abiotic stresses.In this review the mechanisms of plant-aluminium interactions are shown to be influenced by soil mineral nutrients, heavy metals, organic matter, oxidative stress and drought. Described effects of aluminium toxicity include: root growth inhibition, reduction in the uptake of mineral nutrients resulting from the inhibition of transport processes through ion channels; epigenetic changes to DNA resulting in gene silencing. Complex processes occurring in the rhizosphere are highlighted, including the role of soil organic matter and aluminium detoxification by mucilage.There is a considerable research gap in the understanding of root growth in the soil environment in the presence of toxic aluminium concentrations as affected by interactions with abiotic stressors. This knowledge is important for the selection of feasible methods aimed at the reduction of negative consequences of crop production in acidic soils affected by adverse growth environment.