Particle bombardment-mediated transient expression to identify localization signals in plant disease resistance proteins and target sites for the proteolytic activity of pathogen effectors

Transgene-free Genome Editing in Plants

Genome editing is widely used across plant species to generate and study the impact of functional mutations in crop improvement. However, transgene integration in plant genomes raises important legislative concerns regarding genetically modified organisms. Several strategies have been developed to remove or prevent the integration of gene editor constructs, which can be divided into three major categories: 1) elimination of transgenic sequences via genetic segregation; 2) transient editor expression from DNA vectors; and 3) DNA-independent editor delivery, including RNA or preassembled Cas9 protein-gRNA ribonucleoproteins (RNPs). Here, we summarize the main strategies employed to date and discuss the advantages and disadvantages of using these different tools. We hope that our work can provide important information concerning the value of alternative genome editing strategies to advance crop breeding.

Factores que afectan la expresión transitoria del gen GUS en yuca (Manihot esculenta Crantz)

La expresión transitoria es una métodología ampliamente utilizada para el estudio de genes. Sin embargo, hasta la fecha no existe un reporte en donde se utilice esta técnica en hojas de yuca de plantas adultas. Por esta razón este trabajo se centró en la determinación de algunos parámetros críticos para la expresión transitoria del gen GUS en yuca como son: la metodología para introducir la bacteria, la cepa de Agrobacterium, el tiempo post-inoculación, la introducción del gen VirG y la expresión del gen GUS en algunas variedades de yuca. Los resultados indicaron niveles más altos de expresión del gen GUS entre 5-7 días post-inoculación (dpi), agroinfiltrando con la cepa GV3101 y un incremento en la virulencia de esta cepa mediante la introducción del gen VirG. Por último se observaron diferentes niveles de expresión del gen GUS entre las variedades de yuca evaluadas, lo que indica que el factor genético es clave en la eficiencia de la agroinfiltración en este cultivo.

Arabidopsis galactinol synthase AtGolS2 improves drought tolerance in the monocot model Brachypodium distachyon

Brachypodium distachyon (purple false brome) is a herbaceous species belonging to the grass subfamily Pooideae, which also includes major crops like wheat, barley, oat and rye. The species has been established as experimental model organism for understanding and improving cereal crops and temperate grasses. The complete genome of Bd21, the community standard line of B. distachyon, has been sequenced and protocols for Agrobacterium-mediated transformation have been published. Further improvements to the experimental platform including better evaluation systems for transgenic plants are still needed. Here we describe the growth conditions for Bd21 plants yielding highly responsive immature embryos that can generate embryogenic calli for transformation. A prolonged 20-h photoperiod produced seeds with superior immature embryos. In addition, osmotic treatment of embryogenic calli enhanced the efficiency of transfection by particle bombardment. We generated transgenic plants expressing Arabidopsis thaliana galactinol synthase 2 (AtGolS2) in these experiments. AtGolS2-expressing transgenics displayed significantly improved drought tolerance, increasing with increased expression of AtGolS2. These results demonstrate that AtGolS2 can confer drought tolerance to monocots and confirm that Brachypodium is a useful model to further explore ways to understand and improve major monocot crop species.