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.

A hybrid, named tricepiro, was obtained in 1972, by crossing a hexaploid triticale (2n=6x=42) and an octoploid trigopiro (2n=8x=56). The lines achieved include the tricepiro Don René INTA, which has shriveled kernels, and FA-L2, which has smooth ones. The relationship between the heterochromatin content of the rye chromosomes, the seed weight, the presence of meiotic abnormalities and the kernel shriveling has been documented previously in other intergeneric hybrids. The purpose of this study was to determine the average percentage of heterochromatin content in the rye chromosomes of the two tricepiro lines mentioned above and to relate this feature to some characteristics of the meiosis and seeds. We confirmed that the two lines have the same total chromosome number (2n=42) and the same number of rye chromosomes (14). We found that both lines have a complete chromosome mating until late diakinesis, but differ in the percentage of cells with univalents outside the equatorial plate in Metaphase I (Don René 42.85% and FA-L2 14.00%). In addition, the two lines differed in their meiotic index (Don René 66.47% and FA-L2 87.90%) and seed weight (Don René 0.029 ± 0.000 g and FA-L2 0.038 ± 0.001 g). The C-banding in rye chromosomes in mitotic metaphase indicated that the average percentage of heterochromatin content did not differ significantly between the two lines. In contrast to our expectations, the meiotic behavior and seed characteristics were not related to the heterochromatin percentage of the rye chromosomes of the tricepiro lines studied.

Al cruzar un triticale hexaploide (2n=6x=42) y un trigopiro octoploide (2n=8x=56) se obtuvo, en 1972, un híbrido denominado tricepiro. Entre las líneas que se lograron están tricepiro Don René INTA que posee semillas arrugadas y FA-L2 con semillas lisas. El contenido de heterocromatina de los cromosomas de centeno en otros híbridos intergenéricos ha sido relacionado con la rugosidad y peso de las semillas, así como con la presencia de anormalidades meióticas. El objetivo del presente trabajo fue determinar, en ambas líneas mencionadas anteriormente, el porcentaje promedio de heterocromatina presente en los cromosomas de centeno y relacionar este valor con características de la meiosis y de las semillas. Confirmamos que las dos líneas tienen el mismo número cromosómico (2n=42) y el mismo número de cromosomas de centeno (14). Encontramos que ambas presentan un apareamiento completo de los cromosomas hasta diacinesis tardía, pero difieren en el porcentaje de células con univalentes fuera de la placa ecuatorial en Metafase I (Don René 42,.85 % y FA-L2 14,00 %). Además, ambas líneas difieren en el Índice Meiótico (Don René 66,47 % y FA-L2 87,90 %) y en el peso de las semillas (Don René 0,029 ± 0,000 g y FA-L2 0,038 ± 0,001 g). El análisis de las bandas C, hecho en metafases mitóticas, indicó que el porcentaje promedio del contenido de heterocromatina presente en los cromosomas de centeno, no difiere significativamente entre las dos líneas. Contrariamente a nuestras expectativas, el comportamiento meiótico y las características de las semillas no mostraron relación con el porcentaje de heterocromatina presente en los cromosomas de centeno de las líneas híbridas estudiadas.

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.

We studied three different tricepiros: (Don Santiago x Don Noé), (Cumé x Horovitz) and (Cumé x Don Noé). The tricepiro (Don Santiago x Don Noé) was obtained by crossing the triticale Don Santiago INTA (AABBRR, 2n = 6x = 42) with the trigopiro Don Noé INTA (AABBDDJJ, 2n = 8x = 56). The number of chromosomes for the F1 was 2n = 49, the most frequent meiotic configuration being 14 bivalents and 21 univalents. The univalents were situated in the periphery of the equatorial plane, whereas the bivalents were located in the central zone. The chromatids in some of the univalents split when bivalents underwent reductional division in anaphase I. There were few laggard chromosomes or chromatids at this phase. The number of chromosomes (2n = 48-58) was high and variable, and the number of bivalents per cell (18-23) also high in F3 individuals. In all F8 tricepiros (Don Santiago x Don Noé), F12 tricepiros (Cumé x Horovitz) and F12 tricepiros (Cumé x Don Noé), the number of chromosomes (2n = 42) was the same, these retaining the rye genome, as demonstrated by GISH and FISH. These new synthesized allopolyploids constitute interesting models for investigating the evolutionary changes responsible for diploidization, and the chromosomal and genomic re-ordering that cannot be revealed in natural allopolyploids.