Abstract Crops tolerant to drought and salt stress may be developed by two approaches. First, major crops may be improved by introducing genes from tolerant plants. For example, many major crops have wild relatives that are more tolerant to drought and high salinity than the cultivated crops, and, once deciphered, the underlying resilience mechanisms could be genetically manipulated to produce crops with improved tolerance. Secondly, some minor (orphan) crops cultivated in marginal areas are already drought and salt tolerant. Improving the agronomic performance of these crops may be an effective way to increase crop and food diversity, and an alternative to engineering tolerance in major crops. Quinoa (Chenopodium quinoa Willd.), a nutritious minor crop that tolerates drought and salinity better than most other crops, is an ideal candidate for both of these approaches. Although quinoa has yet to reach its potential as a fully domesticated crop, breeding efforts to improve the plant have been limited. Molecular and genetic techniques combined with traditional breeding are likely to change this picture. Here we analyse protein-coding sequences in the quinoa genome that are orthologous to domestication genes in established crops. Mutating only a limited number of such genes by targeted mutagenesis appears to be a promising route for accelerating the improvement of quinoa and generating a nutritious high-yielding crop that can meet the future demand for food production in a changing climate.

Estudio preliminar de la diversidad genética de Ilex guayusa ecuatoriana mediante marcadores inter simple sequence repeat (ISSR) ResumenEvaluamos el grado de diversidad genética de Ilex guayusa, una especie de importancia etnobotánica y comercial para las comunidades indígenas de la Amazonía ecuatoriana. Caracterizamos genéticamente a 157 individuos, provenientes de chacras ubicadas a lo largo de seis provincias, con nueve marcadores ISSR (Inter Simple Sequence Repeats). Se detectó en total 91 bandas polimórficas, pero el índice de heterocigosidad estimada (H e =0.19) de la población reveló un nivel reducido de variabilidad genética para la especie. Los índices de distancias genéticas de Nei (0.013 ≤ Ds ≤ 0.086) revelaron un nivel reducido de divergencia genética entre individuos provenientes de provincias diferentes. De manera similar, el análisis de varianza molecular (AMOVA) demostró que solamente el 18% de la variación observada para I. guayusa ocurre entre poblaciones. El bajo grado de diversidad genética encontrado para I.guayusa puede ser atribuido al hecho de que esta especie es cultivada exclusivamente mediante propagación clonal; una actividad cultural que probablemente ha homogenizado el acervo genético de la especie a lo largo de su rango geográfico de cultivo. El análisis de coordenadas principales (PCoA) demostró que el germoplasma colectado puede estructurarse en tres grupos distintos caracterizados por un leve contraste genético en gradiente direccional, de norte a sur. La inclusión de un mayor número de muestras de provincias sub-representadas (ej. Sucumbíos) y poblaciones silvestres, si existen, ayudaría a esclarecer el nivel de diversidad genética y estructura poblacional de la especie, y la historia de su cultivo en la región.Palabras Clave. Aquifoliaceae, Guayusa, propagación clonal, baja diversidad genética. AbstractWe assessed the degree of genetic diversity of llex guayusa, a species of ethnobotanic and commercial relevance for indigenous communities of the Ecuadorian Amazon. We characterized 157 individuals, from small cultivation sites across six provinces, using nine Inter Simple Sequence Repeat (ISSR) markers. A total of 91 polymorphic bands were detected in, but estimated heterozygosity (He = 0.19) revealed a reduced level of genetic variability. Pairwise-Nei genetic distance indices (0.013 ≤ Ds ≤ 0.086) implied a reduced level of genetic divergence between individuals from different provinces. Accordingly, partitioning of genetic diversity (AMOVA) indicated that only 18% of variation observed for I. guayusa occurred between populations. The low degree of genetic diversity found for I. guayusa could be ascribed to the fact that the species is exclusively cultivated via clonal propagation; a cultural activity which has probably homogenized the species' genetic pool across its geographic range of cultivation. However, PCoA analysis resolved collected germplasm into three distinct groups displaying a subtle genetic contrast in a directional gradient, from north to south. The inclusion o...

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