When exposed to salt, every plant takes up Na+ from the environment. Once in the symplast, Na+ is distributed within cells and between different tissues and organs. There it can help to lower the cellular water potential but also exert potentially toxic effects. Control of Na+ fluxes is therefore crucial and indeed, research shows that the divergence between salt tolerant and salt sensitive plants is not due to a variation in transporter types but rather originates in the control of uptake and internal Na+ fluxes. A number of regulatory mechanisms has been identified based on signaling of Ca2+, cyclic nucleotides, reactive oxygen species, hormones, or on transcriptional and post translational changes of gene and protein expression. This review will give an overview of intra- and intercellular movement of Na+ in plants and will summarize our current ideas of how these fluxes are controlled and regulated in the early stages of salt stress.

Salinity is an ever increasing menace that affects agriculture worldwide. Crops such as rice are salt sensitive, but its degree of susceptibility varies widely between cultivars pointing to extensive genetic diversity that can be exploited to identify genes and proteins that are relevant in the response of rice to salt stress. We used a diversity panel of 306 rice accessions and collected phenotypic data after short (6 h), medium (7 d) and long (30 d) salinity treatment (50 mm NaCl). A genome-wide association study (GWAS) was subsequently performed, which identified around 1200 candidate genes from many functional categories, but this was treatment period dependent. Further analysis showed the presence of cation transporters and transcription factors with a known role in salinity tolerance and those that hitherto were not known to be involved in salt stress. Localization analysis of single nucleotide polymorphisms (SNPs) showed the presence of several hundred non-synonymous SNPs (nsSNPs) in coding regions and earmarked specific genomic regions with increased numbers of nsSNPs. It points to components of the ubiquitination pathway as important sources of genetic diversity that could underpin phenotypic variation in stress tolerance.

Drought and salinity are considered two major abiotic stresses that diminish cotton production worldwide. Studying common morphological and physiological responses in cotton cultivars may help plant biologists to develop and apply standard screening criteria for either of these stresses and for their combination. Therefore, this research aimed to assess the suitability of several physiological parameters as diagnostic to report on osmotic and salinity tolerance in six elite cotton genotypes. Data for relative growth rate (RGR), RGR-reduction, potassium (K + ) concentrations in roots, xylem sap and shoots, stomatal conductance (gs) and net photosynthesis rate (Pn) were assessed. Based on RGR and RGR-reduction, we observed an association between osmotic tolerance and salinity tolerance of cotton genotypes. Furthermore, this study found that tolerant cotton genotypes were better able to maintain high RGR, tissue K + , and gas exchange under both hyperosmotic and saline conditions. Shoot K + levels showed high negative correlations with both osmotic and salinity stress and emerged as a convenient and suitable parameter to assess cotton tolerance to either stress.

El presente artículo discute los hongos fitopatógenos potenciales que afectan al cultivo de arroz en condiciones de desbalance nutricional. A nivel mundial el arroz es considerado como el tercer cultivo alimentario de mayor importancia. Sin embargo, es afectado por diversos hongos fitopatógenos que ocasionan daños en hojas, tallos, panículas y granos del cultivo. La incidencia de estos hongos se debe a factores como la temperatura (25-37 ºC), humedad relativa (70-76%), humedad en el suelo, el viento y desbalance nutricional. El género Rhizoctonia causa manchas con forma elíptica de coloración marrón, pudrición de tallos y panículas, lo que reduce el 19% del rendimiento. Por otra parte, los hongos que se encuentran dentro de los géneros Alternaria, Fusarium, Curvularia y Pyricularia provocan manchas de color café y disminuyen la germinación, rendimiento, peso específico del grano (g L-1). Aunque existen investigaciones acerca de los hongos que afectan al cultivo del arroz, la asociación entre el desbalance nutricional y la incidencia de patógenos aún está por evaluarse en germoplasmas superiores a 100 variedades de arroz en condiciones óptimas y de desbalance nutricional.