Resistance to Diatraea (Lepidoptera: Crambidae) stem borers in sugarcane is independent of species.

Evaluation of host-plant resistance on sugarcane to the sugarcane stem borers of Diatraea spp. is normally conducted in Colombia under field conditions, where environmental variations make the study of the insect-plant relationships difficult. Additionally, several species (i.e., D. saccharalis, D. indigenella, D. tabernella, and D. busckella), which are predominant in Colombia, can overlap in their distribution, raising the question of whether different varieties have the same responses to different pest species. The present study conducted evaluations of host-plant resistance under screen house conditions using two contrasting varieties (CC 93-3895, resistant, and CC 93-3826, susceptible) that were infested with the above-mentioned borer species. Observations of pest injury were conducted on internodes, leaves, and spindles. Survival and size (body mass) of the individuals recovered were analyzed and a Damage Survival Ratio (DSR) was proposed. The resistant CC 93-3895 exhibited less stalk injury, less emergence holes on internodes, and lower DSR; additionally, recovery of pest individuals was lower in comparison with CC 93-3826, independent of the borer species. Insect-plant interactions are discussed, as no previous information was available for three of the species tested (i.e., D. tabernella, D. indigenella, and D. busckella). This screen house protocol is proposed to characterize host-plant resistance among several cultivars from the Colombian sugarcane germplasm bank, using CC 93-3826 and CC 93-3895 as contrasting controls and D. saccharalis as the species model.

COMPARACIÓN MORFO-AGRONÓMICA Y MOLECULAR DE CATORCE VARIEDADES DE ARROZ (Oryza sativa) CON LAS LÍNEAS QUE DIERON SU ORIGEN / Morpho-agronomic and molecular comparison of fourteen varieties of rice (Oryza sativa) with the lines that gave them the origin

RESUMEN Con el objetivo de determinar las diferencias morfo-agronómicas y de calidad, y la diversidad genética entre 14 variedades de arroz de América Latina con sus respectivas líneas de origen, se estableció un estudio (Bloques completos al azar, con 28 genotipos, tres repeticiones y dos siembras en el tiempo), en el cual se midieron 25 variables morfo-agronómicas y de calidad de grano. El análisis molecular se hizo mediante un arreglo de 96 marcadores tipo SNP de alta capacidad de discriminación para arroces Indica. El análisis estadístico se hizo combinando los datos de las dos siembras porque no hubo diferencias estadísticas entre ellas. Además, se analizaron en conjunto los datos moleculares con los morfo-agronómicos y de calidad, usando el índice de Gower para generar una matriz de similitud. Mediante el programa SAS se analizaron los datos agronómicos y moleculares tanto en forma independiente como en conjunto. Los resultados mostraron que, de las 14 variedades, ocho se agruparon con su línea de origen y hubo una variedad que se agrupó con una línea hermana de su ancestro. Los resultados fueron consistentes cuando el análisis de datos se hizo independientemente o combinado. Dada la amplia diversidad encontrada dentro de las variedades y que ninguna fue homocigota al 100 % no se pudieron establecer los perfiles genéticos distintivos de ellas, por lo que se debe hacer la purificación de las variedades para establecer su huella genética.

ABSTRACT This research aimed to determine the morpho-agronomic, grain quality, and molecular differences between 14 rice varieties and their ancestors. These rice varieties from Latin America were tested for 25 variables in a randomized complete block design with 28 genotypes, two planting dates, and three replications. The molecular analysis was done using an array of 96 SNP markers with a high discrimination capacity for Indica rice. A combined statistical analysis was done because there were no statistical differences between the planting dates. Also, molecular, morpho-agronomic, and grain quality data were analyzed together, using the Gower index to generate a similarity matrix. Agronomic and molecular data were analyzed both, together and independently, through the SAS program. Results showed that eight varieties were grouped with their respective ancestor, and one variety was grouped with a sibling of their ancestor and was consistent in all the analyses. However, given the wide heterozygosity found within the varieties, distinctive genetic profiles could not be established; the varieties must be purified to establish their genetic footprint.