Abstract Karyotypes can provide a relevant information about relationships and evolutionary origin among species of the Andropogon genus. This paper presents the karyotype, C+ and DAPI/CMA3 banding and DNA content of three diploid (2n=20) species belonging to section Leptopogon: A. selloanus, A. macrothrix and A. gyrans. Karyotypes of the three diploid species are symmetrical. We propose a karyotype formulae (18m + 2sm) for each of them. The three species show a pair of metacentric chromosomes with a terminal secondary constriction on short arms. Fluorochrome banding revealed different constitutive heterochromatin patterns and CMA3+/DAPI¬ terminal bands related to the nucleolar organizer region in each species. Nuclear DNA content was estimated by flow cytometry ranged from 2.22 to 2.61 pg. FISH technique revealed that these three species have two 45S rDNA loci at the distal ends of the short arms of two metacentric chromosomes. We compare the genomes of the diploids A. selloanus, A. macrothrix and A. gyrans, and the triploid A. ternatus using GISH. These technique allowed us to confirm the hypotheses that the A. selloanus, A. macrothrix and A. gyrans constitute a homogeneous group that share a common S genome that comprises just one of the genomes in the triploid A. ternatus.

Resumen Los cariotipos pueden proporcionar una información relevante sobre las relaciones y el origen evolutivo entre las especies del género Andropogon. Este trabajo presenta el cariotipo, bandeo C+ y DAPI/ CMA3 y contenido de ADN de tres especies diploides (2n = 20) pertenecientes a la sección Leptopogon: A. selloanus, A. macrothrix y A. gyrans. Los cariotipos de las tres especies diploides son simétricos. Proponemos la fórmula cariotípica (18m + 2sm) para cada una de ellas. Las tres especies muestran un par de cromosomas metacéntricos con una constricción secundaria terminal en los brazos cortos. El bandeo fluorocrómico reveló diferentes patrones de heterocromatina constitutiva y bandas CMA3+/DAPI¬ terminales relacionadas con la región organizadora nucleolar en cada especie. El contenido de ADN nuclear se estimó mediante citometría de flujo variando de 2,22 a 2,61 pg. La técnica FISH reveló que estas tres especies poseen dos loci 45S rDNA en los extremos distales de los brazos cortos de dos cromosomas metacéntricos. Comparamos los genomas de los diploides A. selloanus, A. macrothrix y A. gyrans, y del triploide A. ternatus utilizando GISH. Esta técnica nos permitió confirmar la hipótesis de que A. selloanus, A. macrothrix y A. gyrans constituyen un grupo homogéneo que comparte un genoma S común le cual comprende solo uno de los genomas en el triploide A. ternatus.

"Trigopiros" derive from crosses between different species of Triticum L. and Thinopyrum Löve. These synthetic amphiploids are designed with the aim to obtain cereals similar to wheat but which are perennial, resistant to diseases and to the salinity of the soils. Moreover, they allow the transfer of the agronomic attributes of Thinopyrum to wheat. "Trigopiro" Don Noé INTA, which is currently grown in Argentina, presents valuable agronomic traits as well as a high content of seed proteins. In the present work, the use of classical cytogenetic techniques allowed us to confirm that the chromosome number of "Trigopiro" Don Noé is 2n=56. The application of in situ hybridization (FISH-GISH) allowed us to postulate its genomic composition for the first time. This artificial hybrid has 14 chromosomes from genome J of Thinopyrum and 2 chromosomes pairs with putative translocations between Triticum and Thinopyrum. The rest of chromosomes belong to A, B and D genomes of Triticum.

Caracterización del genoma de un Triticum x Thinopyrum (Poaceae) sintético amfiploide utilizando hibridación in situ. Los "Trigopiros" derivan de cruzamientos entre diferentes especies de Triticum y Thinopyrum. El objetivo es obtener cereales con características similares al trigo, perennes, resistentes a enfermedades y a la salinidad de los suelos. Además estos híbridos sintéticos son útiles para transferir al trigo atributos agronómicos de Thinopyrum. "Trigopiro" Don Noé INTA, que se cultiva actualmente en Argentina, presenta rasgos agronómicos valiosos, así como un alto contenido de proteínas seminales. En el presente trabajo se confirmó que el número de cromosomas de "Trigopiro" Don Noé es 2n = 56. Técnicas de hibridación in situ (FISH-GISH) permitieron postular su composición genómica desconocida hasta el momento. Este híbrido artificial posee 14 cromosomas del genoma J de Thinopyrum y 2 pares de cromosomas con posibles translocaciones entre Triticum y Thinopyrum. El resto de los cromosomas pertenecen a los genomas A, B y D de Triticum.

Bacterial artificial chromosome - fluorescence in situ hybridization (BAC-FISH) and cycling-primed in situ labeling (C-PRINS) techniques were evaluated for integration of physical and genetic maps of sunflower (Helianthus annuus L.). Single-site SSR markers were selected from three linkage groups of a high-density sunflower genetic map. This selection was based on previously identified QTL associated to S. sclerotiorum. These markers were used to select BACs contaning single copy sequences for BAC-FISH aplication. Blocking of highly dispersed repetitive sunflower sequences reduced unspecific hybridization, and allowed the detection of specific signals for BACs containing SSR markers HA4222 and HA2600, anchored to LG 16 and LG 10, respectively. Single-site FISH signal detection was optimized by adjusting the relative quantity and quality of unlabelled repetitive sequences present in the blocking DNA. The SSR marker ORS1247 anchored to the LG 17 was detected by C-PRINS, which yielded fluorescence signals that were specific and intense. This progress in localizing single-copy sequences using BAC-FISH and indirect C-PRINS strategies in sunflower will facilitate the integration of genetic and physical maps, allowing the identification of chromosomes containing key genes and/or QTL associated to agronomic important traits in sunflower.