Andrés Zurita-Silva

Variation in salinity tolerance of four lowland genotypes of quinoa (Chenopodium quinoa Willd.) as assessed by growth, physiological traits, and sodium transporter gene expression.

Chenopodium quinoa (Willd.) is an Andean plant showing a remarkable tolerance to abiotic stresses. In Chile, quinoa populations display a high degree of genetic distancing, and variable tolerance to salinity. To investigate which tolerance mechanisms might account for these differences, four genotypes from coastal central and southern regions were compared for their growth, physiological, and molecular responses to NaCl at seedling stage. Seeds were sown on agar plates supplemented with 0, 150 or 300mM NaCl. Germination was significantly reduced by NaCl only in accession BO78. Shoot length was reduced by 150mM NaCl in three out of four genotypes, and by over 60% at 300mM (except BO78 which remained more similar to controls). Root length was hardly affected or even enhanced at 150mM in all four genotypes, but inhibited, especially in BO78, by 300mM NaCl. Thus, the root/shoot ratio was differentially affected by salt, with the highest values in PRJ, and the lowest in BO78. Biomass was also less affected in PRJ than in the other accessions, the genotype with the highest increment in proline concentration upon salt treatment. Free putrescine declined dramatically in all genotypes under 300mM NaCl; however (spermidine+spermine)/putrescine ratios were higher in PRJ than BO78. Quantitative RT-PCR analyses of two sodium transporter genes, CqSOS1 and CqNHX, revealed that their expression was differentially induced at the shoot and root level, and between genotypes, by 300mM NaCl. Expression data are discussed in relation to the degree of salt tolerance in the different accessions.

Quinoa biodiversity and sustainability for food security under climate change. A review

Climate change is rapidly degrading the conditions of crop production. For instance, increasing salinization and aridity is forecasted to increase in most parts of the world. As a consequence, new stress-tolerant species and genotypes must be identified and used for future agriculture. Stress-tolerant species exist but are actually underutilized and neglected. Many stress-tolerant species are indeed traditional crops that are only cultivated by farmers at a local scale. Those species have a high biodiversity value. Besides, the human population will probably reach nine billion within coming decades. To keep pace with population growth, food production must increase dramatically despite the limited availability of cultivable land and water. Here, we review the benefits of quinoa, Chenopodium quinoa Willd., a seed crop that has endured the harsh bioclimatic conditions of the Andes since ancient times. Although the crop is still mainly produced in Bolivia and Peru, agronomic trials and cultivation are spreading to many other countries. Quinoa maintains productivity on rather poor soils and under conditions of water shortage and high salinity. Moreover, quinoa seeds are an exceptionally nutritious food source, owing to their high protein content with all essential amino acids, lack of gluten, and high content of several minerals, e.g., Ca, Mg, Fe, and health-promoting compounds such as flavonoids. Quinoa has a vast genetic diversity resulting from its fragmented and localized production over the centuries in the Andean region, from Ecuador to southern Chile, and from sea level to the altiplano. Quinoa can be adapted to diverse agroecological conditions worldwide. Year 2013 has therefore been declared the International Year of Quinoa by the United Nations Food and Agriculture Organization. Here, we review the main characteristics of quinoa, its origin and genetic diversity, its exceptional tolerance to drought and salinity, its nutritional properties, the reasons why this crop can offer several ecosystem services, and the role of Andean farmers in preserving its agrobiodiversity. Finally, we propose a schematic model integrating the fundamental factors that should determine the future utilization of quinoa, in terms of food security, biodiversity conservation, and cultural identity.

Breeding quinoa (Chenopodium quinoa Willd.): potential and perspectives

Quinoa (Chenopodium quinoa Willd.) originated in the Andean region of South America; this species is associated with exceptional grain nutritional quality and is highly valued for its ability to tolerate abiotic stresses. However, its introduction outside the Andes has yet to take off on a large scale. In the Andes, quinoa has until recently been marginally grown by small-scale Andean farmers, leading to minor interest in the crop from urban consumers and the industry. Quinoa breeding programs were not initiated until the 1960s in the Andes, and elsewhere from the 1970s onwards. New molecular tools available for the existing quinoa breeding programs, which are critically examined in this review, will enable us to tackle the limitations of allotetraploidy and genetic specificities. The recent progress, together with the declaration of “The International Year of the Quinoa” by the Food and Agriculture Organization of the United Nations, anticipates a bright future for this ancient species.

Seasonal fluctuations in Vitis vinifera root respiration in the field

We studied the seasonal fluctuation of soil respiration (R(S)), and its root-dependent (R(R)) and basal (R(B)) components, in a Vitis vinifera (Chardonnay) vineyard. The R(S) components were estimated through independent field methods (y-intercept and trenching) and modeled on the basis of a Q(10) response to soil temperature, and fine and coarse root respiration coefficients. The effect of assimilate availability on R(R) was assessed through a trunk girdling treatment. The apparent Q(10) for R(R) was twice that of R(B) (3.5 vs 1.6) and increased linearly with increasing vine root biomass. The fastest R(R) of fine roots was during rapid fruit growth and the fastest R(R) of coarse roots was immediately following fruit development. R(S) was estimated at 32.6 kg ha(-1) d(-1) (69% as a result of R(R) ) for the hottest month and at 7.6 kg ha(-1) d(-1) (18% as a result of R(R)) during winter dormancy. Annual R(S) was low compared with other natural and cultivated ecosystems: 5.4 Mg ha(-1) (46% as a result of R(R)). Our estimates of annual vineyard R(S) are the first for any horticultural crop and suggest that the assumption that they are similar to those of annual crops or forest trees might lead to an overestimation.

Root-endophytes improve the ecophysiological performance and production of an agricultural species under drought condition

Antarctic root-endophytes can improve the physiological tolerance and productivity of lettuce crops by means of several different physiological and molecular mechanisms, and could be a successful strategy to maximize water use efficiency and hence maintain an optimal yield in zones affected by desertification. Thus, application of antarctic root-endophytes to different crops could be a biotechnological tool for food security.

Effect of water availability on physiological performance and lettuce crop yield (Lactuca sativa)

M.A. Molina-Montenegro, A. Zurita-Silva, and R. Oses. 2011. Effect of water availability on physiological performance and lettuce crop yield (Lactuca sativa). Cien. Inv. Agr. 38(1): 65-74. Water is essential for plants, affecting the majority of the physiological processes related to growth and productivity. Water shortage is one of the most common factors that limit crop productivity worldwide. Many cultivars have elevated water requirements, nevertheless in some countries due to global climate change effects, the availability of water for irrigation is becoming limited. In fact, current models of climate changes predict that central Chile will be a sensitive zone where precipitation will drastically decrease. In this study, the variation of gas exchange and production of fresh biomass in a lettuce cultivar, grown under different water availability regimes, was evaluated. Additionally, the concentration of total soluble sugar and water use efficiency (WUE) as mechanisms related to water shortage responses were also evaluated. Overall, individuals with the lowest water availability (50%) showed lower gas exchange and fresh biomass values than their conspecifics grown in optimal irrigated conditions. On the other hand, those individuals with moderate water shortage showed the highest concentration of total soluble sugars and WUE. Our results suggested that cultures exposed to extensive or intense drought events, could be negatively affected in both physiological performance and productivity. Nevertheless, slight decreases in water availability can enable lettuce plants to exhibit a high WUE, maintaining high levels of physiological performance and productivity.

Evaluación de la tolerancia a estrés por sequía en cuatro genotipos naturalizados de vid (Vitis vinifera) provenientes del norte de Chile

El cultivo de la vid (Vitis vinifera) se caracteriza por sufrir sequias estacionales en la mayoria de las regiones productoras, situacion que se incrementa en ambientes aridos y semiaridos de Chile, los cuales han sufrido disminuciones de precipitaciones y prolongados periodos de sequia, siendo una de las principales problematicas que afectan la productividad de las vides en el norte del pais. El objetivo planteado fue analizar las respuestas morfo-fisiologicas en genotipos naturalizados de vides expuestas a estres hidrico y determinar su nivel de tolerancia. Se evaluaron parametros fisiologicos y arquitecturales en cuatro genotipos de vides (10, 93, 134, 148), provenientes de un gradiente latitudinal en zonas aridas y semiaridas del norte de Chile (18°S a 32°S). Mediante el uso de un sistema de mini-rizotrones, material clonal de los cuatro genotipos fue sometido a tratamientos de estres hidrico leve y severo (60% y 40% de capacidad de campo, respectivamente), durante tres meses, bajo un diseno completamente aleatorio. Se obtuvieron diferencias significativas a nivel de tratamientos para la sobrevivencia y longitud de tallo, distancia entrenudos y todos los parametros de desempeno fisiologico evaluados. Asimismo, se obtuvieron diferencias significativas entre los genotipos en caracteres de longitud de raiz, distancia entrenudos, fotosintesis y potencial hidrico. Ello permitio identificar genotipos an-hisohidricos como 134 y 148, de genotipos isohidricos, como 10 y 93 en relacion al comportamiento de respuesta al estres. La determinacion de efectos tempranos de la sequia en desarrollo, sobrevivencia, y desempeno fisiologico, permitio diferenciar al genotipo 134 como el mas tolerante de los evaluados. La metodologia utilizada permitira seleccionar nuevos genotipos para uso potencial como portainjertos o injertos en zonas aridas y semiaridas, subrayando el rol fundamental de explorar la variabilidad genetica de vides y su uso como cultivo modelo