Author Archive

Integration of phenotyping and genetic platforms for a better; understanding of wheat performance under drought

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Experimental Botany, 2014.

Lopes, M.S.; Rebetzke, G.J.; Reynolds, M.P.

Identifying markers for physiological traits of proven value in breeding, especially ones that are consistent across environments with different patterns of stress, strengthens the toolkit to increase confidence in the value and delivery from physiological breeding. To identify markers relevant to drought adaptation, this review will highlight the importance of development and implementation of robust and repeatable phenotyping that is relevant to the different target drought types, and practical examples of managed environment facilities in Australia and Mexico are given. These facilities can be used as models to: (i) improve reliability and consistency of environments and genetic responses to the environment at a global scale; (ii) improve the capacity to deliver quantitative trait loci (QTLs) as user-friendly markers for enriching populations; and (iii) illustrate the use of populations with a narrow range of variation for phenology allowing the identification of QTLs for drought-adaptive traits. However, the importance of further optimizing phenology and plant height at a global scale is highlighted. Finally, the impact of physiological trait-based crossing is demonstrated and supports the need for urgent development of robust genetic markers.

Socio-economic factors affecting adoption of modern information and communication technology by farmers in India: analysis using multivariate

Posted by Carelia Juarez on , in Journal Articles

Published in The Journal of Agricultural Education and Extension, 2014.

Mittal, S.; Mehar, M.

Purpose: The paper analyzes factors that affect the likelihood of adoption of different agriculture-related information sources by farmers. Design/Methodology/Approach: The paper links the theoretical understanding of the existing multiple sources of information that farmer use, with the empirical model to analyze the factors that affect the farmer’s adoption of different agriculture-related information sources. The analysis is done using a multivariate probit model and primary survey data of 1,200 farmer households of five Indo-Gangetic states of India, covering 120 villages. Findings: The results of the study highlight that farmer’s age, education level and farm size influence farmer’s behaviour in selecting different sources of information. The results show that farmers use multiple information sources, that may be complementary or substitutes to each other and this also implies that any single source does not satisfy all information needs of the farmer. Practical implication: If we understand the likelihood of farmer’s choice of source of information then direction can be provided and policies can be developed to provide information through those sources in targeted regions with the most effective impact. Originality/Value: Information plays a key role in a farmer’s life by enhancing their knowledge and strengthening their decision-making ability. Farmers use multiple sources of information as no one source is sufficient in itself.

Holistic risk index: A case study of cattle producers in the protected area of farrapos estuaries-Uruguay

Posted by Carelia Juarez on , in Journal Articles

Published in Agroecology and Sustainable Food Systems 39 (2209-223, 2014.

Gazzano, I.; Altieri, M.A.; Achkar, M.; Burgueño, J.

Agricultural intensification promotes floods and threatens family livestock production in the protected area of Farrapos Estuaries, Uruguay. Using the Holistic Risk Index (Barrera, J. F., Herrera, J., and J. Gómez. Riesgo-vulnerabilidad hacia la broca del café bajo un enfoque de manejo holístico. La Broca del Café en América Tropical: Hallazgos y Enfoques. ECOSUR-SME 2007), this study analyzes the interrelationships among threat, vulnerability and responsiveness. Four livestock producers were shown to have low risk due to their high responsiveness; eighteen producers were shown to have medium risk and were divided into high vulnerability, low vulnerability and increased responsiveness groups; and three producers were shown to have high risk due to high threat and vulnerability and a lower responsiveness. Responsiveness is related to the use of agroecological principles and the agroecological criteria that guide strategies among producers and within the protected area.

A DNA Microarray-based assay to detect dual infection with two dengue virus serotypes

Posted by Carelia Juarez on , in Journal Articles

Published in Sensors 14 (57580-7601, 2014.

Diaz-Badillo, A.; Muñoz, M.L.; Perez-Ramirez, G.; Altuzar, V.; Burgueño, J.; Mendoza-Alvarez, J.G.; Martínez-Muñoz, J.P.; Cisneros, A.; Navarrete-Espinosa, J.; Sanchez-Sinencio, F.

Here; we have described and tested a microarray based-method for the screening of dengue virus (DENV) serotypes. This DNA microarray assay is specific and sensitive and can detect dual infections with two dengue virus serotypes and single-serotype infections. Other methodologies may underestimate samples containing more than one serotype. This technology can be used to discriminate between the four DENV serotypes. Single-stranded DNA targets were covalently attached to glass slides and hybridised with specific labelled probes. DENV isolates and dengue samples were used to evaluate microarray performance. Our results demonstrate that the probes hybridized specifically to DENV serotypes; with no detection of unspecific signals. This finding provides evidence that specific probes can effectively identify single and double infections in DENV samples.

Functional water flow pathways and hydraulic regulation in the xylem network of Arabidopsis hydraulic regulation of water flows in xylems

Posted by Carelia Juarez on , in Journal Articles

Published in Plant and Cell Physiology, 2014.

Park, J.; Hae Koo Kim; Ryu, J.; Ahn, S.; Lee, S.J.; Hwang, I.

In vascular plants, the xylem network constitutes a complex microfluidic system. The relationship between vascular network architecture and functional hydraulic regulation during actual water flow remains unexplored. Here, we developed a method to visualize individual xylem vessels of the three-dimensional xylem network of Arabidopsis thaliana, and to analyze the functional activities of these vessels using synchrotron X-ray computed tomography with hydrophilic gold nanoparticles as flow tracers. We show how the organization of the xylem network changes dynamically throughout the plant, and reveal how the elementary units of this transport system are organized to ensure both long-distance axial water transport and local lateral water transport. Xylem vessels form distinct clusters that operate as functional units and the activity of these units, which determines water flow pathways, is modulated by varying not only the number and size of xylem vessels, but also by altering their interconnectivity and spatial arrangement. Based on these findings, we propose a regulatory model of water transport that ensures hydraulic efficiency and safety.

Accelerating the switchgrass (Panicum virgatum L.) breeding cycle using genomic selection approaches

Posted by Carelia Juarez on , in Journal Articles

Published in PLoS ONE, 2014.

Lipka, A.E.; Fei Lu; Cherney, J.H.; Buckler, E.S.; Casler, M.D.; Costich, D.E.

Switchgrass (Panicum virgatum L.) is a perennial grass undergoing development as a biofuel feedstock. One of the most important factors hindering breeding efforts in this species is the need for accurate measurement of biomass yield on a per-hectare basis. Genomic selection on simple-to-measure traits that approximate biomass yield has the potential to significantly speed up the breeding cycle. Recent advances in switchgrass genomic and phenotypic resources are now making it possible to evaluate the potential of genomic selection of such traits. We leveraged these resources to study the ability of three widely-used genomic selection models to predict phenotypic values of morphological and biomass quality traits in an association panel consisting of predominantly northern adapted upland germplasm. High prediction accuracies were obtained for most of the traits, with standability having the highest ten-fold cross validation prediction accuracy (0.52). Moreover, the morphological traits generally had higher prediction accuracies than the biomass quality traits. Nevertheless, our results suggest that the quality of current genomic and phenotypic resources available for switchgrass is sufficiently high for genomic selection to significantly impact breeding efforts for biomass yield.

Genome size variation in guayule and mariola: fundamentaldescriptors for polyploid plant taxa

Posted by Carelia Juarez on , in Journal Articles

Published in Industrial Crops and Products 54 1-5, 2014.

Sanchez, P.L.;Costich, D.E.; Friebe, B.; Coffelt, T.A.; Jenks, M.A.; Gore, M.A.

Guayule (Parthenium argentatum A. Gray) has tremendous potential as a domestic source of natural rubber production in the southwestern United States. However, genetic improvement of guayule has been slowed by its complex mode of reproduction, natural ploidy series, and lack of genetic and genomic resources. The interspecific hybridization of guayule with its closest sister taxon mariola (P. incanum Kunth) offers an opportunity to access novel genetic variation for guayule breeding programs, but mariola accessions available from the U.S. National Plant Germplasm System (NPGS) have never been evaluated for natural variation in ploidy level. In addition, the nuclear genome sizes for guayule and mariola at any ploidy level are unknown. To that end, we examined the ploidy of 10 mariola accessions, which revealed a natural polyploid series ranging from triploid (2n = 3x = 54) to pentaploid (2n = 5x = 90). In contrast, a ploidy analysis of five guayule accessions uncovered a natural polyploid series that ranged from diploid (2n = 2x = 36) to hexaploid (2n = 6x = 108). More than one ploidy level among individual plants (mixed ploidy) and instances of aneuploid plants were observed for accessions of both guayule and mariola. The nuclear genome sizes of guayule and mariola were similar at identical ploidy levels, and the genome size of diploid guayule (1624 Mb) was almost twofold smaller than the genomes of sunflower (H. annuus L. 2n = 2x = 34) and lettuce (L. sativa L.; 2n = 2x = 18), two other Compositae (Asteraceae) species that are being genome-sequenced. The results from this study will serve as a foundation for interspecific breeding and genome sequencing of guayule and mariola.

Evaluation of advance wheat lines for agronomic traits in rainfed environment

Posted by Carelia Juarez on , in Journal Articles

Published in Pakistan Journal Agricultural Research 27 (279-88, 2014.

Sohail, M.; Hussain, I.; Din, R.;Tanveer, S.K.; Qamar, M.; Abbas, S.H.

Wheat under rainfed conditions of Pothwar region of Pakistan is usually exposed to limited soil moisture during early growth period and high temperature stress during reproductive growth stage. Better yield under stressful environment is the main objective while evaluating genotypes for rainfed ecologies. A field study was conducted at National Agricultural Research Centre (NARC), Islamabad, Pakistan to evaluate the agronomic traits of three advance lines (NR-397, NR-379 and NR-400) in comparison to released variety (NARC-09) under rainfed conditions during crop season 2010-2011. Crop was sown on normal (November 15) and late (December 15) planting times to create variable growing conditions especially during reproductive growth period. The adverse effect of the late planting was significant (P<0.05) on grain yield of the crop. Late planting produced 29% lower grain yield than normal planting. Genotypes also showed significant variation (P<0.05) regarding grain yield production under both normal and late sowing dates. Under more stressful growing conditions (late planting), minimum grain yield reduction was noticed in line NR-397 (19%) followed by NARC-09 (20%), NR-400 (30%) and NR-379 (35%). Late planting conditions also signi- -2 ficantly reduced days to maturity, spikes m and 1000-grain weight in all genotypes as compared to normal sowing; however, the reduction in these parameters were significantly less (P<0.05) in wheat lines NR-397 and NARC-09 as compared to other two genotypes. Results showed that comparatively higher grain yields of lines NR-397 and NARC-09 were correlated to their better leaf chlorophyll retention and maintenance of low canopy temperature during grain filling periods particularly under late planting conditions. Findings of this study have indications that wheat sowing up to November 15 is more appropriate time and advance lines NR- 397 and NARC-09 have the genetic potential to tolerate adverse rainfed growing conditions under agro-ecological conditions of Pothwar region, Pakistan.

Physio-agronomic traits evaluation of wheat genotypes for Adaptability under rainfed conditions

Posted by Carelia Juarez on , in Journal Articles

Published in Sarhad Journal AGriculture 30 (2151-156, 2014.

Sohail, M.;Hussain, I.; Din, R.; Tanveer, S.K.; Qamar, M.; Abbas, S.H.

High temperature stress during grain filling stages is one of the main wheat yield limiting factors under rainfed conditions of Pakistan. A field experiment was carried out to evaluate physio-agronomic traits of different wheat genotypes for better yield and heat tolerance under rainfed conditions. Variable growing conditions during grain filling period were created by sowing crop on normal (November 15) and late sowing dates (December 15). Crop planted on normal sowing date had significant affect (p<0.05) and produced 29% higher grain yield as compared to late planting. Significant variation (p<0.05) was also noticed among genotypes in terms of physiological and agronomic traits under both under both normal and late sowing dates, as advance line NR-397 and NARC-09 produced significantly higher (p<0.05) grain yields as compared to NR-400 and NR-379. Higher grain yields of these two cultivars were associated with their more number of days to maturity, higher spikes m2 and heavier grains as compared to other two genotypes. At the same time, grain yields of wheat genotypes showed a strong correlation to their leaf chlorophyll (+0.98) and canopy temperature (-0.99) measurements. Higher grain yields of NR-397 and NARC-09 were directly correlated to the