SummaryThe genetic nature of tree adaptation to drought stress was examined by utilizing variation in the drought response of a full-sib second generation (F 2 ) mapping population from a cross between Populus trichocarpa (93-968) and P. deltoides Bart (ILL-129) and known to be highly divergent for a vast range of phenotypic traits. We combined phenotyping, quantitative trait loci (QTL) analysis and microarray experiments to demonstrate that 'genetical genomics' can be used to provide information on adaptation at the species level. The grandparents and F 2 population were subjected to soil drying, and contrasting responses to drought across genotypes, including leaf coloration, expansion and abscission, were observed, and QTL for these traits mapped. A subset of extreme genotypes exhibiting extreme sensitivity and insensitivity to drought on the basis of leaf abscission were defined, and microarray experiments conducted on these genotypes and the grandparent species. The extreme genotype groups induced a different set of genes: 215 and 125 genes differed in their expression response between groups in control and drought, respectively, suggesting species adaptation at the gene expression level. Co-location of differentially expressed genes with drought-specific and drought-responsive QTLs was examined, and these may represent candidate genes contributing to the variation in drought response.

Dedicated non‐food bioenergy crops like poplar are needed as sustainable, low‐input feedstocks for renewable energy in a future drier climate, where they can be grown on marginal soils. Such plants should have a low water, carbon, and chemical footprint. Capturing natural variation in traits associated with water use efficiency (WUE) is the first step to developing trees that require less water and may be adapted to drier environments. We have assessed stomatal conductance (gs) and leaf carbon isotope composition (δ13C, an indirect indicator of leaf WUE) in two Populus species, P. deltoides and P. trichocarpa and their F2 progeny, grown in the United Kingdom and in Italy. Populus deltoides leaves showed lower δ13C than P. trichocarpa, suggesting a higher WUE in P. trichocarpa, although without drought preconditioning, gs of P. trichocarpa was less responsive to dehydration and abscisic acid treatment than P. deltoides, suggesting that leaf anatomy may also contribute to δ13C in Populus. Quantitative trait loci (QTL) were identified for δ13C on eight linkage groups (LG) and two QTL for gs. From these. QTL and differential gene expression in response to drought from microarray data, we focused on three hotspots and identified 23 novel candidate genes on LG VI, X, and XVI. We have begun to unravel the genetic basis of WUE in bioenergy Populus revealing important underpinning data for breeding and improvement in poplar genotypes for a future drier climate.

RESUMEN:La relación maguey-hombre mesoamericano data de hace 10 mil años y el aprovechamiento de la planta para elaborar pulque se remonta aproximadamente a tres mil años. Esta agroindustria que floreció entre 1870 a 1900 ha decaído, lo que pone en riesgo el aprovechamiento tradicional y otros más rentables como la producción de inulina y jarabe de fructosa. Se documentó el aprovechamiento del maguey pulquero en localidades de Puebla y Tlaxcala, seleccionadas por muestreo aleatorio estratificado. Los datos taxonómicos, socioeconómicos, de gestión y actividades de productores, tlachiqueros y consumidores, se recabaron mediante entrevistas estructuradas y observación participativa. Se identificaron siete tipos de magueyes, cultivados en superficies promedio de tres ha; se describieron las labores culturales y actividades propias de los productores. El aprovechamiento sustantivo fue la elaboración del pulque a partir de magueyes de 10 a 14 años de madurez, mediante prácticas culturales tradicionales. Las herramientas para la producción, transporte de aguamiel y elaboración de pulque han sido sustituidas por materiales más resistentes y duraderos, que no necesariamente han mejorado el proceso y calidad del pulque. La duración del ciclo del cultivo, poca demanda de pulque, baja rentabilidad económica y ausencia de normas de protección para la planta, han provocado la disminución de la superficie de cultivo del maguey y la erosión del conocimiento del cultivo y su aprovechamiento. La permanencia del maguey pulquero dependerá de las acciones efectuadas en conjunto por las autoridades, los miembros de la cadena productiva e investigadores, y programas que incentiven el interés e incremento del cultivo de esta planta. ABSTRACT:The man-maguey relationship in Mesoamerica, and the use of the plant for pulque production goes back 10 000 years ago and three thousand years respectively. This agro-industry that flourished in the last third of the nineteenth century is at risk even its traditional use and others more profitable uses such as the production of inulin and fructose syrup with high demand in the international market. The use of maguey was documented and compared in localities of four municipalities of Puebla and Tlaxcala, selected by means of stratified random sampling. Data of taxonomic, socio-economic, management and activities of producers, "tlachiqueros" 207 and consumers, were collected through structured interviews and observational participation. The results showed seven types of maguey, on areas of three ha in average, imbricated with maize, barley and bean, of which cultural practices and activities proper of producers are described. The most important was the elaboration of pulque, using maguey plants from 10 to 14 years of age. The cultivation and use have been maintained over the years. The tools used for the recollection, transport and processing of aguamiel and production of pulque have been replaced by more resistant and durable materials, which have not necessarily improved the process and quality of p...

No abstract

No abstract