Mutations Found in the Asc1 Gene That Confer Susceptibility to the AAL-Toxin in Ancestral Tomatoes from Peru and Mexico.

Tomato susceptibility/resistance to stem canker disease caused by Alternaria alternata f. sp. lycopersici and its pathogenic factor AAL-toxin is determined by the presence of the Asc1 gene. Several cultivars of commercial tomato (Solanum lycopersicum var. lycopersicum, SLL) are reported to have a mutation in Asc1, resulting in their susceptibility to AAL-toxin. We evaluated 119 ancestral tomato accessions including S. pimpinellifolium (SP), S. lycopersicum var. cerasiforme (SLC) and S. lycopersicum var. lycopersicum "jitomate criollo" (SLJ) for AAL-toxin susceptibility. Three accessions, SP PER018805, SLC PER018894, and SLJ M5-3, were susceptible to AAL-toxin. SLC PER018894 and SLJ M5-3 had a two-nucleotide deletion (nt 854_855del) in Asc1 identical to that found in SLL cv. Aichi-first. Another mutation (nt 931_932insT) that may confer AAL-toxin susceptibility was identified in SP PER018805. In the phylogenetic tree based on the 18 COSII sequences, a clade (S3) is composed of SP, including the AAL-toxin susceptible PER018805, and SLC. AAL-toxin susceptible SLC PER018894 and SLJ M5-3 were in Clade S2 with SLL cultivars. As SLC is thought to be the ancestor of SLL, and SLJ is an intermediate tomato between SLC and SLL, Asc1s with/without the mutation seem to have been inherited throughout the history of tomato domestication and breeding.

Micropropagación de Prosopis pallida (Humb &Bonpl. Ex Willd.) Kunth a partir de yemas apicales / Micropropagation of Prosopis pallida (Humb &Bonpl. Ex Willd.) Kunth from shoot tips

RESUMEN Prosopis pallida, conocido como algarrobo, es una especie emblemática de los bosques secos del norte del Perú. Es de gran importancia económica por su uso en la producción de leña y carbón, así como en la producción de algarrobina proveniente de sus frutos. Actualmente las actividades humanas han deforestado grandes poblaciones de algarrobo en el bosque seco, por lo que es muy importante una propagación masiva para planes de reforestación a gran escala en esos ecosistemas, con la finalidad de conservar la especie y también las características genéticas de individuos élite. El objetivo de la investigación fue establecer un protocolo para la propagación in vitro de algarrobo. Previo a la siembra in vitro, se evaluaron tres tratamientos pregerminativos para poder acelerar la germinación de las semillas con la finalidad de obtener mayor material de propagación. Luego se evaluó el efecto del medio de plantas leñosas con la adición de cuatro concentraciones (0; 0,5; 1,0 y 1,5 mg/L) de citoquininas (BAP y ZEA) sobre la propagación in vitro de Prosopis pallida, habiendo realizado tres ensayos debido a la poca efectividad de brotación de las yemas apicales, resultando mejor la ausencia de citoquininas en yemas apicales con sus dos cotiledones, usando tapas de algodón en los tubos de ensayo. En esta etapa se evaluó el número de nudos, altura de plántula y número de brotes. Para el enraizamiento se ensayó con tres concentraciones (0; 0,5 y 1,0 mg/L) de auxinas (NAA, IBA y IAA), y se evaluó el porcentaje de enraizamiento, longitud de la raíz y número de raíces; obteniéndose mejores resultados con 0,5 mg/L IBA. En la fase de aclimatación se evaluó el porcentaje de aclimatación en dos tipos de sustratos, obteniéndose mejores resultados con sustrato comercial de turba y vermiculita.

ABSTRACT Prosopis pallida, known as algarrobo, is an emblematic species of the dry forests of northern Peru. It is of great economic importance for its use in the production of firewood and coal, as well as in the production of carob from its fruits. Currently human activities have deforested large populations of algarrobo in the dry forest, so it is very important a massive propagation for large-scale reforestation plans in these ecosystems, in order to conserve the species and also the genetic characteristics of elite individuals. The objective of the research was to establish a protocol for the in vitro propagation of algarrobo. Before in vitro propagation, It was evaluated the effect of three seeds treatments to accelerate seeds germination in order to get more propagation material. Then, the effect of woody plants medium with the addition four concentrations (0, 0.5, 1.0 and 1.5 mg /L) of cytokinins (BAP and ZEA) on the in vitro propagation of Prosopis was evaluated and it has performed three trials for the ineffective budding of apical buds, resulting in a better absence of cytokinins in apical buds with their two cotyledons, and using cotton lids in the test tubes. In this stage the number of nodes, seedling height and number of shoots was evaluated. For rooting, it was tested with three concentrations (0, 0.5 and 1.0 mg /L) of auxins (NAA, IBA and IAA), and the percentage of rooting, root length and amount of roots was evaluated, obtaining better results with 0.5 mg / L IBA. In the acclimation phase, the acclimation percentage was evaluated using two substrates, and the best results were commercial substrate of peat and vermiculite.