SUMMARYFruit ripening in tomato (Solanum lycopersicum L.) is well understood at the molecular level. However, information regarding genetic pathways associated with tomato ovary and early fruit development is still lacking. Here, we investigate the possible role(s) of the microRNA156/SQUAMOSA promoter-binding protein-like (SPL or SBP box) module (miR156 node) in tomato ovary development. miR156-targeted S. lycopersicum SBP genes were dynamically expressed in developing flowers and ovaries, and miR156 was mainly expressed in meristematic tissues of the ovary, including placenta and ovules. Transgenic tomato cv. MicroTom plants over-expressing the AtMIR156b precursor exhibited abnormal flower and fruit morphology, with fruits characterized by growth of extra carpels and ectopic structures. Scanning electron microscopy and histological analyses showed the presence of meristem-like structures inside the ovaries, which are probably responsible for the ectopic organs. Interestingly, expression of genes associated with meristem maintenance and formation of new organs, such as LeT6/TKN2 (a KNOX-like class I gene) and GOBLET (a NAM/ CUC-like gene), was induced in developing ovaries of transgenic plants as well as in the ovaries of the natural mutant Mouse ear (Me), which also displays fruits with extra carpels. Conversely, expression of the MADS box genes MACROCALYX (MC) and FUL1/TDR4, and the LEAFY ortholog FALSIFLORA, was repressed in the developing ovaries of miR156 over-expressors, suggesting similarities with Arabidopsis at this point of the miR156/SPL pathway but with distinct functional consequences in reproductive development. Altogether, these observations suggest that the miR156 node is involved in maintenance of the meristematic state of ovary tissues, thereby controlling initial steps of fleshy fruit development and determinacy.

This study aimed to fingerprint 36 water yam (Dioscorea alata) accessions using microsatellite markers. Ten accessions were collected in local markets from several municipalities in Brazil, eight were obtained from the 'Instituto Agronômico de Campinas' (IAC) germplasm collection and eighteen were collected directly from growers from São Paulo state. A total of nine microsatellite loci were used in the analysis. Loci revealed high polymorphism verified by elevated PIC values (0.57-0.77), and by high gene diversity and Shannon-Wiener indices (0.69 and 1.29 on average, respectively). The accessions were classified into two groups based on clustering analysis. One group contained mostly accessions from the IAC collection, including a commercial cultivar acquired in a market in the city of Cuiabá, Mato Grosso state. The second group was composed of most accessions, including those collected directly from growers and markets in São Paulo, a few accessions from the IAC collection, and an accession from Puerto Rico, named 'Florida', which is the most cultivated in Brazil. Several duplicates were identified in this study, including accessions obtained from two farmers in Mogi Guaçu and Mogi Mirim, São Paulo state. However, some of these accessions were allocated in different sub-groups, within this second group. Results suggested the hypothesis of different origins for accessions currently cultivated in Brazil. Similar accessions obtained from different municipalities revealed the commercialization of the same accessions at different locations.

IntroducciónLa diversidad de pisos ecológicos presentes en la Amazonía peruana, ha permitido a través de los siglos, la domesticación de numerosas especies de plantas nativas con una alta variabilidad genética (Zapata 2003). La impresionante diversidad biológica hace que muchas de estas especies no hayan sido estudiadas en profundidad, desconociendo aún muchas características biológicas, genéticas y fitoquímicas. Plukenetia volubilis L., sacha inchi es una planta nativa de la Amazonía peruana, cuyas semillas presentan altos contenidos de proteínas, ácidos grasos (esenciales: omegas 3, 6; omega 9) y vitamina E (tocoferoles y tocotrienoles) en cantidades significativamente mayores que otras semillas de oleaginosas como el maní, palma, soya, maíz, colza y girasol (Hamaker 1992).El valor del sacha inchi radica no sólo en los aspectos alimenticios, culturales e históricos, sino también en su rentabilidad económica. Siendo un cultivo con potencial rendimiento económico y grandes posibilidades de industrialización (Arévalo 1995), viene siendo intensamente cultivado; sin embargo, se observa una alta variabilidad genética, morfológica y fitoquímica, lo que ha generado que en el proceso de expansión del cultivo se hayan llegado a confundir especies del género Plukenetia. Hasta el año 2008 fueron descritas para la Amazonía peruana, cuatro especies en base a caracteres morfológicos: P. volubilis L., P. brachybotrya Müll. Arg., P. loretensis Ule, y P. polyadenia Müll. Arg. Recientemente fue descrita, para la región Amazonas, P. huayllabambana Bussmann, C. Téllez & A. Glenn. Nuestras observaciones en la morfología de algunas colecciones biológicas del Herbarium Amazonense (AMAZ) indican cierta sobreposición en algunos de los caracteres de estas especies, lo que podría dificultar su correcta determinación.Los marcadores moleculares constituyen poderosas herramientas para esclarecer cuestiones no resueltas mediante la taxonomía morfológica y para determinar los límites taxonómicos. Así, el ADN han sido utilizado para comprobar la sistemática morfológica o para cuestionarla (Judd et al. 1999). La litera- ResumenEn el presente trabajo se estudian cinco especies del género Plukenetia de la Amazonía peruana: P. brachybotrya, P. loretensis, P. polyadenia, P. huayllabambana, P. volubilis (procedencia San Martín); y de un supuesto morfotipo (P. volubilis, procedencia Cusco). Los 126 especímenes estudiados fueron identificados mediante claves de caracteres morfológicos (formas de hojas, tallos y semilla; posición de glándulas basilaminares) y posteriormente mediante marcadores moleculares ISSR (CAA, CAG, GACA). Los análisis morfológicos permitieron separar las cinco especies descritas: P. brachybotrya, P. loretensis, P. polyadenia, P. volubilis y P. huayllabambana. Los dos supuestos morfotipos de P. volubilis fueron discriminados por la posición de las glándulas, tamaño de semillas y forma del tallo. Los resultados proporcionados por el Análisis Factorial de Correspondencia (AFC) y corroborados por el Índice de fijación (F ST ), distan...

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A new arbuscular mycorrhizal (AM) fungus, Microkamienskia peruviana, was detected in bait cultures for arbuscular mycorrhizal fungi established with rhizospheric soil substrates of the inka nut (Plukenetia volubilis). The field soil derived from three agricultural plantations in the Amazonia lowlands of the province Lamas, San Martin State, in Peru. The fungus was subsequently propagated in single species cultures on Sorghum sp., Brachiaria sp.,Medicago sativa and P. volubilis as host plants. The new species differentiates hyaline spores regularly in spore clusters, up to 500–800×400–600 μm. The spores are 16–31(–36)×13–29(–35) μm in diam, formed on cylindrical or slightly funnel-shaped hyphae, without a septum at or close to the spore base. Phylogenetically, the new fungus belongs to a new genus, named Microkamienskia, which has as type species M. perpusilla comb. nov. and to which also M. divaricata comb. nov. belongs. Both are transferred from Kamienskia to Microkamienskia in the present study. The new fungus can be identified by the ballooning semi-persistent to evanescent outer spore wall layer in PVLG-based mountants that is not known for the other species of these two genera, nor for any other glomeromycotan species of similar small spore sizes. Kamienskia and Microkamienskia species can be distinguished by their position in the phylogenetic tree and by hyaline spores, open pores at the spore bases and in the subtending hyphae, and by their spore sizes that are for Microkamienskia among the smallest spore sizes so far detected for AM fungi (15–35 μm).

La diversidad genética poblacional de sacha inchi Plukenetia volubilis L. fue estimado mediante la técnica DALP (Amplificación Directa de Polimorfismo de Longitud), en cuatro localidades deL departamento de San Martín. Para lo cual, un total de 83 muestras fueron colectadas en las localidades de Habana (21), Shica (20), Cerro Alto (21) y Tununtunumba (21). El estudio fue basado en el análisis de ocho marcadores DALP; de los cuales, tres (DALP221, DALP233 y DALP242) resultaron ser informativos para esta especie, mostrando diferencias a nivel intra e interpoblacional. Los resultados del Análisis Factorial de Correspondencia (AFC), Índice de fijación (promedio de Fst = 0.83) y distancia genética (promedio de D = 2.56) muestran que las cuatro poblaciones estudiadas forman entidades genéticas independientes. Esto, podría ser atribuido al sistema mixto de polinización (autógamo y alógamo) presente en esta especie, que estaría actuando preferentemente dentro de cada población y no entre las poblaciones. A nivel intrapoblacional, la población Shica presento la mayor diversidad genética (15 genotipos) entre las cuatro poblaciones estudiadas, lo cual estaría relacionado con el mayor tamaño y densidad poblacional, que favorecería la polinización cruzada, trayendo como consecuencia una mayor diversidad genética. La alta divergencia (diferenciación) genética encontrada entre las cuatro poblaciones evaluadas, podría ser causada por la ausencia de insectos polinizadores directos, así como por la presencia de barreras naturales y por la distancia geográfica entre ellas, que estaría restringiendo el flujo de genes entre las poblaciones.

Arbuscular mycorrhizal (AM) fungi are key soil microorganisms that establish a mutualistic symbiotic relationship with plants. The establishment of crops represents an environmental filter that usually reduces the diversity and variability of AM fungal communities, affecting the ecosystem stability and functionality. Despite several studies addressing these effects, the temporal development of these soil microbes since crop establishment has not been studied. We hypothesized that the negative effect of cropping practices in terms of reducing AM fungal richness, phylogenetic, and beta diversity will increase in time as far as the new dynamics progressively filter the AM fungal community composition. This research tested the impact of crop establishment and the role that time has in the progressive assembly of soil microbial communities. The AM fungal communities were characterized using terminal restriction fragment length polymorphism in coffee (Coffea arabica) plantations of different ages established in previous pristine tropical forest. We found that intraradical colonization and AM fungal phylogenetic diversity increased with plantation age. AM fungal richness was constant across time but a significant compositional turnover was detected. In relation to our initial hypothesis, these unexpected results face the current general view of the negative effects of crops on soil microbial diversity and highlight the need of studying temporal dynamics when assessing human impacts on soil biodiversity. Nevertheless, next steps would imply to put in context the found patterns by relativizing them to the original natural diversity inhabiting the studied areas.

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