William Roca

Tissue culture storage of potato germplasm: Culture initiation and plant regeneration

Abstract Plants were regenerated from axillary shoot tips of 12 Andean potato clones, chosen to cover the full range of ploidies from 2X to 5X, and one European tuberosum clone. Using Murashige and Skoog (MS) medium supplemented with 0.1 mg/l gibberellic acid (GA) and naphthaleneacetic acid (NAA) (singly or in combination), single-shoot cultures were initiated from 20–30% of the tuberosum explants but from only 5–10% of explants from the Andean clones. With the latter clones, multiple-shoot cultures were produced from 50–100% of the explants when they were allowed to produce a small basal callus on MS medium supplemented with 3.0 mg/l benzylaminopurine (BAP), before being transferred to MS medium supplemented with 0.1 mg/l GA. Once roots were formed, plantlets could be readily established in soil.

Pesticide Contamination has Little Effect on the Genetic Diversity of Potato Species

Our previous study examining the effects of agrichemicals on the reproductive capacity of potato species revealed that the pesticide carbofuran negatively influenced flowering duration and pollen viability. These changes could limit reproductive ability non-randomly, modify allelic frequencies, and cause genetic drift. This study utilized Simple Sequence Repeat (SSR) markers to examine that possibility by assessing the genetic structure of progenies derived from potato populations exposed to two levels of carbofuran. A total of eight populations of five potato species (acl, buk, hcr, med and rap) were evaluated. An untreated, uncontaminated population was included as control for comparison. The results revealed that most of the 116 SSR allele frequencies assessed did not differ significantly between control and progenies of pesticide-contaminated parents. A few markers showed a significant frequency shift in some species, specifically buk and med. However, this study reveals that although the pesticide reduces reproduction in wild potato species populations, changes in population genetics are minor and do not significantly threaten diversity.ResumenNuestro estudio previo sobre los efectos de los agroquímicos en la capacidad reproductiva de especies de papa reveló que el plaguicida carbofurán influenció negativamente la duración de la floración y la viabilidad del polen. Estos cambios pudieran limitar la habilidad reproductiva no al azar, modificar las frecuencias alélicas y causar cambio genético. En este estudio se utilizaron marcadores de Repeticiones de Secuencia Simple (SSR) para examinar esa posibilidad, mediante el análisis de la estructura genética de las progenies derivadas de poblaciones de papa expuestas a dos niveles de carbofuran. Se evaluaron un total de ocho poblaciones de cinco especies de papa (acl, buk, hcr, med y rap). Se incluyó una población no tratada, no contaminada, como testigo de comparación. Los resultados revelaron que la mayoría de las frecuencias alélicas de los 116 SSR analizados no difirieron significativamente entre el testigo y las progenies de padres contaminados con el plaguicida. Unos cuantos marcadores mostraron una frecuencia de cambio significativa en algunas especies, específicamente buk y med. No obstante, este estudio revela que aunque el plaguicida reduce la reproducción en poblaciones de especies silvestres de papa, los cambios en la genética de las poblaciones son menores, y no amenazan significativamente a la diversidad.