Sugarcane is one of the most important industrial crops in tropical and subtropical regions. INTA (Argentina) administrates a Sugarcane Germplasm Bank and carries out a breeding program. The current study was designed to assess the phenotypic and genetic diversity among 65 sugarcane accessions selected from the INTA bank. Clustering and ordination methods based on quantitative and qualitative morphological traits and SSR data, were applied. Generalized Procrustes Analysis allowed evaluating the correlation between relationships established with both markers. A good fit between dendrograms and similarity matrices were revealed by high cophenetic coefficients (r=0.82, p<0.0001; r=0.73, p<0.0001; r=0.82, p<0.0001 for phenotypic quantitative, phenotypic qualitative and molecular data respectively). The presence of different reliable population structure was observed when considering different data sources. Procrustes allowed finding those accessions that should have been responsible for the low correlation found between the individual configurations (73%). Both morphologic and molecular markers resulted discriminative enough to differentiate among accessions. It was not possible, however, to correlate associations of markers with the origin of materials. Phenotypic and genetic distances based on morphology and molecular information serves to assist conservation and organization of collection of materials, and the choice of parent combinations for breeding purposes.

La caña de azúcar es uno de los cultivos industriales más importantes de regiones tropicales y subtropicales. El INTA (Argentina) administra un Banco de Germoplasma de caña de azúcar y lleva a cabo un programa de mejora. El presente trabajo fue diseñado para estimar la variabilidad fenotípica y genética entre 65 accesiones de caña de azúcar seleccionadas del INTA. Se aplicaron métodos de clasificación y ordenamiento en el análisis de datos morfológicos y de SSR. EL Análisis de Procrustes Generalizado permitió evaluar la correlación entre las relaciones establecidas a partir de ambos tipos de marcadores. Un buen ajuste entre los dendrogramas y las matrices de similitud fue soportado por un alto coeficiente de correlación cofenética (r=0,82, p<0,0001; r=0,73, p<0,0001; r=0,82, p<0,0001 para datos cuantitativos, cualitativos y moleculares respectivamente). La presencia de una estructura poblacional fue reconocida cuando se consideraron los diferentes tipos de datos. El Procrustes permitió detectar aquellas accesiones que serían responsables de la baja correlación detectada entre configuraciones individuales (73%). Tanto los marcadores morfológicos como los moleculares resultaron lo suficientemente discriminativos para diferenciar accesiones. No obstante, no fue posible correlacionar las asociaciones establecidas por los marcadores con el origen de los materiales. Las distancias fenotípicas y genéticas basadas en información morfológica y molecular será de utilidad para asistir en la conservación y organización de los materiales de la colección y elegir combinaciones parentales con propósito de mejora.

Understanding the population structure and genetic diversity in sugarcane (Saccharum officinarum L.) accessions from INTA germplasm bank (Argentina) will be of great importance for germplasm collection and breeding improvement as it will identify diverse parental combinations to create segregating progenies with maximum genetic variability for further selection. A Bayesian approach, ordination methods (PCoA, Principal Coordinate Analysis) and clustering analysis (UPGMA, Unweighted Pair Group Method with Arithmetic Mean) were applied to this purpose. Sixty three INTA sugarcane hybrids were genotyped for 107 Simple Sequence Repeat (SSR) and 136 Amplified Fragment Length Polymorphism (AFLP) loci. Given the low probability values found with AFLP for individual assignment (4.7%), microsatellites seemed to perform better (54%) for STRUCTURE analysis that revealed the germplasm to exist in five optimum groups with partly corresponding to their origin. However clusters shown high degree of admixture, F ST values confirmed the existence of differences among groups. Dissimilarity coefficients ranged from 0.079 to 0.651. PCoA separated sugarcane in groups that did not agree with those identified by STRUCTURE. The clustering including all genotypes neither showed resemblance to populations find by STRUCTURE, but clustering performed considering only individuals displaying a proportional membership > 0.6 in their primary population obtained with STRUCTURE showed close similarities. The Bayesian method indubitably brought more information on cultivar origins than classical PCoA and hierarchical clustering method.

O metabólito secundário 2-tridecanona, secretado pelos tricomas glandulares tipo VI das folhas de tomateiro silvestre, Lycopersicon hirsutum L., confere-lhe resistência a uma grande variedade de insetos, inclusive a traça-do-tomateiro, Tuta absoluta (Meyrick). O objetivo do trabalho foi avaliar a concentração de 2- tridecanona, a densidade de tricomas glandulares tipo VI e o grau de infestação da traça-do-tomateiro na cultivar suscetível 'Uco Plata' (Lycopersicon esculentum Mill.), na linhagem resistente PI 134417 (L. hirsutum f. glabratum) e em suas progênies F1 e F2. Foram avaliadas ainda as possíveis associações entre a concentração de 2-tridecanona, a densidade de tricomas glandulares tipo VI e o grau de infestação da traça-do-tomateiro. O grau médio de infestação da traça-do-tomateiro em 'Uco Plata' foi significativamente superior ao obtido em PI 134417. Ainda que a concentração de 2-tridecanona tenha sido significativamente superior no parental resistente, a presença deste metabólito somente explicaria parcialmente a resistência (R² = 8,17%). Não se detectaram diferenças significativas na densidade de tricomas tipo VI entre o parental suscetível e o resistente. Este comportamento ocorreu independentemente do conteúdo de 2-tridecanona e do grau de infestação da traça-do-tomateiro.

The secondary metabolite 2-tridecanone, secreted by the type VI glandular trichomes present in the leaves of Lycopersicon hirsutum L., make it resistant to a great variety of insects, including the tomato pinworm, Tuta absoluta (Meyrick). The 2-tridecanone concentration, the type VI glandular trichome densities and the pinworm infestation degree were evaluated on the Lycopersicon esculentum Mill. susceptible cultivar 'Uco Plata', on the Lycopersicon hirsutum f. glabratum resistant accession PI 134417 and on their F1 and F2. The mean infestation degree with pinworm larvae was significantly higher in 'Uco Plata' than in PI 134417. The 2-tridecanone concentration was significantly higher in the resistant parent, but the presence of this metabolite could only partially account for the resistance (R²= 8.17%). No significant differences were detected in the type VI glandular trichomes densities between the susceptible and resistant parents. This trait was independent of the 2-tridecanone level and the pinworm infestation degree.

Os tricomas glandulares presentes nas folhas e ramos das plantas do gênero Lycopersicon são responsáveis pela secreção de metabólitos de diferentes naturezas. A presença de alguns desses compostos tem sido associada à resistência do tomate a diferentes insetos. A traça-do-tomateiro, Tuta absoluta (Meyrick), é uma das pragas mais nocivas da América do Sul. O adulto oviposita sobre as folhas do tomate e suas larvas abrem galerias no mesófilo das folhas, ramos, flores e frutos. As espécies silvestres do tomate conservam a capacidade de biossintetizar compostos químicos que lhes conferem resistência a esta praga. No presente trabalho, foi avaliada a preferência para oviposição desse inseto sobre folhas com e sem tricomas glandulares de L. esculentum (Mill.) cv. Uco Plata, suscetível, e de L. hirsutum f. glabratum (Mull.) PI 134417, espécie silvestre afim ao tomate, e resistente à traça. Os resultados sugerem que as fêmeas ovipositam indistintamente sobre as folhas de ambas espécies, independentemente da presença, ou não, dos tricomas glandulares. E a presença destes e de seus exsudatos não têm efeito inibidor na oviposição do inseto.

In the genus Lycopersicon, different metabolites are secreted by the glandular trichomes of leaves and stems. These compounds have been associated to different tomato pests resistance. The South American tomato pinworm, Tuta absoluta (Meyrick), is one of the most harmful pests in South America. The females oviposit on tomato leaves and the larvae mine the leaf mesophyl, stems, flowers and fruits. Some wild accessions of Lycopersicon keep their capacity to synthesize allelochemicals that protect them from the pest. In this paper a comparison was made between the tomato pinworm oviposition on leaves with and without trichomes of L. esculentum (Mill.) cv. Uco Plata, a susceptible cultivar, and L. hirsutum f. glabratum (Mull.) PI 134417, a resistant wild accession. Results suggest that the female oviposit without distinction on the leaves of both species, with or without glandular trichomes. The presence of these trichomes and their exudates do not have an inhibitor effect on the insect oviposition.