Examinando por Autor "Orjeda, Gisella"

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Comparing the differential expression of selected genes in native Peruvian potatoes in response to early and late drought conditions
(Palm Beach State College, 2017-04-01) Cornelio, Laynet; Perez, Indira; Vazquez, Carlos; Martinez, Diana; Ponce, Olga Patricia; Murata, Emi; Torres, Yerisf; Zuñiga López, Luz Noemí; Orjeda, Gisella; Maul, Dora Pilar; Merino, Carlos
Plant response to drought stress comprises growth inhibition, stomatal closure, an increase in abscisic acid (ABA) biosynthesis and increased antioxidant metabolism, among others. Drought tolerance in plants is linked to photosynthesis and carbohydrate metabolism. Drought-inducible functional proteins include those that protect cells from water deficit and oxidation as well as transcription factors and signaling molecules associated with the water-stress response. Native potatoes from the Andean regions of Peru, Ecuador and Bolivia grow at altitudes as high as 11483 ft. (3500m) above sea level. Because of their high genetic diversity, they are well adapted to the harsh environmental conditions that prevail in the high Andes, including drought. This makes them ideal candidates for gene expression studies associated with drought tolerance. St. Thomas University is collaborating with the Universidad Peruana Cayetano Heredia (UPCH, Lima, Peru), and the Instituto Nacional de Innovacion Agraria (INIA, Huancayo, Peru) in a gene expression study in native potatoes associated with early and late drought responses. Selected drought associated candidate genes from RNA-seq analysis were used in primer design and quantitative RT-PCR analysis. Differential gene expression in tolerant vs. susceptible cultivars has been confirmed for two heat shock proteins, a dehydration-response element binding protein and for a major pollen allergen.
Multi-environment multi-QTL association mapping identifies disease resistance QTL in barley germplasm from Latin America
(Springer Nature, 2014-12-30) Gutiérrez, Lucia; Germán, Silvia; Pereyra, Silvia; Hayes, Patrick M.; Pérez, Carlos A.; Capettini, Flavio; Locatelli, Andres; Berberian, Natalia M.; Falconi, Esteban E.; Estrada Zúniga, Rigoberto; Fros, Dario; Gonza Cusipuma, Víctor Antonio; Altamirano Vasquez, Hernan; Huerta Espino, Julio; Neyra Valdez, Edgar; Orjeda, Gisella; Sandoval Islas, Sergio; Singh, Ravi; Turkington, Kelly; Castro, Ariel J.
Diseases represent a major constraint for barley (Hordeum vulgare L.) production in Latin America. Spot blotch (caused by Cochliobolus sativus), stripe rust (caused by Puccinia striiformis f.sp. hordei) and leaf rust (caused by Puccinia hordei) are three of the most important diseases that affect the crop in the region. Since fungicide application is not an economically or environmentally sound solution, the development of durably resistant varieties is a priority for breeding programs. Therefore, new resistance sources are needed. The objective of this work was to detect genomic regions associated with field level plant resistance to spot blotch, stripe rust, and leaf rust in Latin American germplasm. Disease severities measured in multi-environment trials across the Americas and 1,096 SNPs in a population of 360 genotypes were used to identify genomic regions associated with disease resistance. Optimized experimental design and spatial modeling were used in each trial to estimate genotypic means. Genome-Wide Association Mapping (GWAS) in each environment was used to detect Quantitative Trait Loci (QTL). All significant environment-specific QTL were subsequently included in a multi-environment-multi-QTL (MEMQ) model. Geographical origin and inflorescence type were the main determinants of population structure. Spot blotch severity was low to intermediate while leaf and stripe rust severity was high in all environments. Mega-environments were defined by locations for spot blotch and leaf rust. Significant marker-trait associations for spot blotch (9 QTL), leaf (6 QTL) and stripe rust (7 QTL) and both global and environment-specific QTL were detected that will be useful for future breeding efforts.