Stress salinity in plants: New strategies to cope with in the foreseeable scenario.

The excess of salts in soils causes stress in most plants, except for some halophytes that can tolerate higher levels of salinity. The excess of Na+ generates an ionic imbalance, reducing the K+ content and altering cellular metabolism, thus impacting in plant growth and development. Additionally, salinity in soil induces water stress due to osmotic effects and increments the production of reactive oxygen species (ROS) that affect the cellular structure, damaging membranes and proteins, and altering the electrochemical potential of H+, which directly affects nutrient absorption by membrane transporters. However, plants possess mechanisms to overcome the toxicity of the sodium ions, such as internalization into the vacuole or exclusion from the cell, synthesis of enzymes or protective compounds against ROS, and the synthesis of metabolites that help to regulate the osmotic potential of plants. Physiologic and molecular mechanisms of salinity tolerance in plants will be addressed in this review. Furthermore, a revision of strategies taken by researchers to confer salt stress tolerance on agriculturally important species are discussed. These strategies include conventional breeding and genetic engineering as transgenesis and genome editing by CRISPR/Cas9.

Evaluación del potencial biotecnológico de un promotor derivado del virus de la distorsión de la hoja de maracuyá (PLDV), un begomovirus que infecta maracuyá / Evaluation of the biotechnological potential of a promoter derived from passion fruit leaf distortion virus (PLDV), a begomovirus that infects passionfruit

RESUMEN Los avances biotecnológicos en plantas requieren la bioprospección de nuevos promotores para la expresión de genes de interés agronómico, en particular, es necesario caracterizar nuevos promotores con expresión tejido específica. El objetivo de esta investigación fue evaluar la actividad de expresión del promotor del gen AV1 que codifica para la proteína de la cápside (CP) del virus de la distorsión de la hoja de maracuyá (Passion fruit leaf distortion virus, PLDV) mediante ensayos transitorios de biobalística de baja presión. Se realizó un análisis de la región promotora del gen AV1 empleando herramientas bioinformáticas. Se construyó una fusión traduccional (CP-PLDV-GUS), que porta la región promotora del gen AV1 de PLDV fusionada al gen reportero uidA (GUS). CP-PLDV-GUS fue bombardeado sobre hojas de plántulas de tabaco cultivadas in vitro empleando una pistola de genes. Como control positivo se utilizó el plásmido pBI121 que porta el gen GUS bajo el control del promotor 35S de CaMV. Se llevaron a cabo 11 repeticiones, donde la unidad experimental fue la hoja y la variable de respuesta, la expresión transitoria del gen GUS representado por el número de puntos azules observados en las hojas bombardeadas. Como resultado, el análisis estadístico no paramétrico demostró que existe evidencia muestral suficiente para confirmar que, tanto el promotor AV1 del PLDV y 35S de CaMV presentan una actividad de expresión semejante. Finalmente, el promotor del gen AV1 de PLDV mostró una fuerte actividad de expresión del gen reportero en las células del mesófilo de las hojas, el cual podría ser usado para conferir expresión tejido específica en plantas transgénicas.

ABSTRACT Biotechnological advances in plants require the bioprospecting of new promoters for the gene´s expression of agronomic interest, in particular, it is necessary to characterize new promoters with tissue-specific expression The objective of this research was to evaluate the expression activity of the AV1 gene promoter that codes for the capsid protein (CP) of the Passion fruit leaf distortion virus (PLDV) by means of transient tests of low pressure biobalistics. An analysis of the promoter region was carried out using bioinformatics tools. A CP-PLDV-GUS translational fusion was constructed, which carries the promoter region of the AV1 gene of PLDV fused to the uidA reporter gene (GUS). CP-PLDV-GUS was bombarded on leaves of tobacco seedlings grown in vitro using a gene gun. As a positive control pBI121 carrying the GUS gene under the control of the 35S promoter of CaMV was used. It was carried out 11 repetitions where the experimental unit was the leaf and the response variable the transient expression of the GUS gene represented by number of blue dots observed in the bombarded leaves. As a result, the non-parametric statistical analysis showed that there is sufficient sample evidence to confirm that both the AV1 promoter of PLDV and 35S of CaMV exhibit similar expression activity. Finally, the promoter of the AV1 gene of PLDV showed a strong activity of expression of the reporter gene in the leaf mesophyll cells, which could be used to confer tissue-specific expression in transgenic plants.

Molecular identification of a new begomovirus infecting yellow passion fruit (Passiflora edulis) in Colombia.

The complete genome sequence of a bipartite begomovirus (genus Begomovirus, family Geminiviridae) infecting yellow passion fruit (Passiflora edulis) in the state of Valle del Cauca (Colombia) has been determined. The complete DNA-A and DNA-B components were determined to be 2600 and 2572 nt in length, respectively. The DNA-A showed the highest nucleotide sequence identity (87.2 %) to bean dwarf mosaic virus (M88179), a begomovirus found in common bean crops in Colombia, and only 77.4 % identity to passion fruit severe leaf distortion virus (FJ972767), a begomovirus identified infecting passion fruit in Brazil. Based on its sequence identity to all other begomoviruses known to date and in accordance with the ICTV species demarcation criterion for the genus Begomovirus (≥91 % sequence identity for the complete DNA-A), the name passion fruit leaf distortion virus is proposed for this new begomovirus. To our knowledge, this is the first report of a bipartite begomovirus affecting passion fruit in Colombia and the second report of a geminivirus affecting this crop worldwide.

Primer reporte de un begomovirus presente en maracuyá amarillo [Passiflora edulis f. flavicarpa (Degener)] en Valle del Cauca, Colombia / First report of a begomovirus presents in yellow passionfruit [Passiflora edulis f. flavicarpa (Degene)] in Valle del Cauca, Colombia

El maracuyá amarillo es un cultivo de importancia económica para el Valle del Cauca, pero en los últimos años ha presentado una reducción de hasta un 80% en la producción debido a problemas virales. El objetivo del presente trabajo fue detectar y caracterizar parcialmente begomovirus que podrían estar afectando los cultivos de maracuyá amarillo localizados en dos zonas productoras del Valle del Cauca (La Unión y Palmira). Se colectaron hojas de maracuyá con síntomas típicos de enfermedad viral, se purificó su DNA genómico y se detectó la presencia de begomovirus bipartitas mediante PCR empleando cebadores específicos para el componente A y B, respectivamente. Cinco fragmentos de DNA correspondientes al genoma geminiviral A y B, fueron clonados, secuenciados y analizados con herramientas bioinformáticas. Los resultados evidencian por primera vez en Colombia de la presencia de un begomovirus en maracuyá amarillo. El análisis de la secuencias de nucleótidos indica que este begomovirus está más relacionado con el virus del mosaico enano del frijol, un geminivirus que afecta frijol en Colombia, y no con el virus de la distorsión severa de la hoja de maracuyá, el cual se reportó afectando maracuyá amarillo en Brasil. A la fecha, este resultado constituiría el primer reporte de un begomovirus (perteneciente a la familia Geminiviridae) que afecta maracuyá amarillo en Colombia y que podría ser diferente de otros begomovirus previamente reportados a nivel mundial afectando este cultivo.

The yellow passion fruit is a crop of economic importance to the Valle del Cauca, but in recent years has been a reduction of up to 80% in production due to viral problems. The aim of this study was to detect and characterize partially begomovirus that could be affecting crops of yellow passionfruit located in two growing areas of the Valle del Cauca (La Union and Palmira). Passionfruit leaves with typical symptoms of viral disease were collected, purified genomic DNA and its bipartite begomovirus were detected by PCR using primers specific for component A and B, respectively. Five DNA fragments corresponding to geminiviral A and B genome were cloned, sequenced and analyzed with bioinformatics tools. The results show for the first time in Colombia the presence of a begomovirus in yellow passionfruit. The analysis of the nucleotide sequences indicates that this begomovirus is more related to bean BDMV, a geminivirus affecting beans in Colombia, not PSLDV, which was reported affecting yellow passionfruit in Brazil. To date, this result would be the first report of a begomovirus (belonging to the family Geminiviridae) affecting yellow passion fruit in Colombia, and that might be different from other begomovirus previously reported worldwide affecting this crop.