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The genus Cedrela comprises endangered and highly valuable species in the forestry sector. Based on molecular genetics, we describe the natural distribution areas, ecological niches, and current state of four Cedrela species distributed in Argentina, in order to apply proper conservation strategies, guide germplasm collection, and design suitable seed orchards. Genetic variability patterns of C. angustifolia populations are associated with the latitudinal and altitudinal gradients of distribution, as well as with its selective logging history in the Yungas Rainforest; instead, genetic patterns of C. balansae were related to the short geographic distance among their populations and the high levels of historical gene flow between them. Molecular evidence of hybrid zones between C. balansae and C. saltensis in the Yungas Rainforest is presented together with their genetic patterns of variation and geographical delimitation of their altitudinal ranges. In addition, the molecular identification was used for the specific purification of clonal seed orchards of C. balansae. In the Alto Parana Rainforest, genetic variability of C. fissilis populations was evaluated. Strategies for use and conservation of Cedrela genetic resources are discussed.

Species of Cedrela with a high economic value from Northwest and Northeastern Argentina are severely exploited. This work evaluates whether 51 nuclear SSRs, developed to study phylogenetically close species in the Meliaceae family (Cedrela odorata, Cedrela fissilis, Swietenia humilis and Swietenia macrophylla), can be used to study C. fissilis, Cedrela balansae, Cedrela saltensis and Cedrela angustifolia. A 62.8% of the total of 194 SSRs/species combinations showed a successful, homologous and cross-species amplification. As expected, a great success in SSRs transferability among Cedrela species was observed. Twenty-one screened SSRs showed a successful amplification pattern in all target species and many of them were polymorphic (9, 13, 13 and 7 SSRs for C. fissilis, C. balansae, C. saltensis and C. angustifolia, respectively). The high number of evaluated SSRs from the Cedrela genus and Meliaceae family, allowed us to obtain a suitable set of validated markers that are highly variable and easily scored, and also identify those which were less sturdy. We were able to retain a useful set of markers for three of the target species, but not for C. angustifolia. This could be due to its greater phylogenetic and morphological distances to the other three species. The lack of SSRs developed for our target species, transforms the transferred SSRs reported here in a valuable tool to monitor the genetic consequences of forest overexploitation on Cedrela species.

The effects of different simulated rainfall regimes on water relations, growth, and biomass production and allocation of five provenances of Cedrela fissilis, C. saltensis and C. balansae were assessed in a pot-grown seedling experiment in greenhouse under uncontrolled conditions. Four simulated rainfall regimes were applied: 600 mm year−1 (severe water deficit), 800 mm year−1 (mild water deficit), 1,000 mm year−1 (mild wet), and 1,200 mm year−1 (well-watered) used as control. Provenances were compared in terms of water relations (midday leaf water potential, Ψ md and relative water content, RWC), growth (root, shoot and leaf length, neck diameter), growth rate (shoot- and neck growth rate, SGR and NGR), biomass production (root, shoot and leaf dry weight), and biomass allocation (root:shoot ratio, RSR). Multivariate analyses revealed that water relations differed significantly under all simulated rainfall treatments by means of several variables throughout time. Effects of species × treatment, and provenance nested within species × treatment interactions significantly were important. SGR and RSR also were important to explain differences in Ψ md and RWC between treatments and provenances. Broadly C. balansae and C. saltensis provenances seem to display a better performance than C. fissilis provenances under severe water deficit only. However, despite differences between provenances, it was not possible to clearly separate them according to their origin, based on water relations and growth performance. Even though the results of this study performed on pot-grown seedlings are based on relatively few observations and require additional confirmation, they allow an opportunity for speculation on the factors that are related to intraspecific variations that are likely to occur during the growth of seedlings from different geographical sites in field condition. Fil: Ruiz, Verónica Eugenia. Universidad Nacional de Tucuman. Facultad de Cs.naturales E Instituto Miguel Lillo. Catedra de Fisiologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; Argentina Fil: Meloni, Diego. Universidad Nacional de Santiago del Estero. Facultad de Cs.forestales. Instituto de Silvicultura y Manejo de Bosques; Argentina Fil: Fornes, Luis. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucumán-santiago del Estero. Estación Experimental Agropecuaria Famaillá; Argentina Fil: Ordano, Mariano Andrés. Fundacion Miguel Lillo. Direccion de Botanica. Instituto de Ecologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; Argentina Fil: Hilal, Mirna. Universidad Nacional de Tucuman. Facultad de Cs.naturales E Instituto Miguel Lillo. Catedra de Fisiologia Vegetal; Argentina Fil: Prado, Fernando Eduardo. Universidad Nacional de Tucuman. Facultad de Cs.naturales E Instituto Miguel Lillo. Catedra de Fisiologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; Argentina

Cedrela balansae C.DC. is a native tree species in Argentina, severely exploited for its timber features. We performed a molecular analysis to understand the genetic diversity and its distribution in eight remaining populations, which are distributed within the species' range in the Argentine Yungas Rainforest. We used two molecular markers: (i) seven SSRs, selected from forty-five SSRs developed for phylogenetically close species belonging to the Meliaceae family and (ii) 382 polymorphic AFLPs. The He was 0.643 and 0.222 for SSRs and AFLPs, respectively. The moderate levels of genetic diversity were related to the limited size of the species' distribution area, the latitudinal position of populations, the impacts of logging and the species' spatial distribution pattern. Genetic differentiation among populations was low for both markers (4.9% and 4.1% for SSRs and AFLPs, respectively). Four genetic clusters homogeneously distributed were distinguished. These observations may relate to the considerable historical gene flow measured (3.71 and 4.47 for SSRs and AFLPs, respectively). To safeguard the currently existing genetic base in the species, we identify four priority populations for conservation. To date only one of these is located in a protected area. Therefore, it is urgent to apply additional conservation measures for the remaining populations.

The endangered Cedrela balansae C.DC. (Meliaceae) is a high-value timber species with great potential for forest plantations that inhabits the tropical forests in Northwestern Argentina. Research on this species is scarce because of the limited genetic and genomic information available. Here, we explored the transcriptome of C. balansae using 454 GS FLX Titanium next-generation sequencing (NGS) technology. Following de novo assembling, we identified 27,111 non-redundant unigenes longer than 200 bp, and considered these transcripts for further downstream analysis. The functional annotation was performed searching the 27,111 unigenes against the NR-Protein and the Interproscan databases. This analysis revealed 26,977 genes with homology in at least one of the Database analyzed. Furthermore, 7,774 unigenes in 142 different active biological pathways in C. balansae were identified with the KEGG database. Moreover, after in silico analyses, we detected 2,663 simple sequence repeats (SSRs) markers. A subset of 70 SSRs related to important “stress tolerance” traits based on functional annotation evidence, were selected for wet PCR-validation in C. balansae and other Cedrela species inhabiting in northwest and northeast of Argentina (C. fissilis, C. saltensis and C. angustifolia). Successful transferability was between 77% and 93% and thanks to this study, 32 polymorphic functional SSRs for all analyzed Cedrela species are now available. The gene catalog and molecular markers obtained here represent a starting point for further research, which will assist genetic breeding programs in the Cedrela genus and will contribute to identifying key populations for its preservation. Fil: Torales, Susana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Recursos Biológicos; Argentina Fil: Rivarola, Maximo Lisandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina Fil: Gonzalez, Sergio. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina Fil: Inza, María Virginia. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Recursos Biológicos; Argentina Fil: Pomponio, María Florencia. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Recursos Biológicos; Argentina Fil: Fernández, Paula. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina Fil: Acuña, Cintia Vanesa. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Zelener, Noga. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Recursos Biológicos; Argentina Fil: Fornes, Luis Fernando. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucuman-Santiago del Estero; Argentina Fil: Hopp, Horacio Esteban. Universidad de Belgrano. Facultad de Ciencias Exactas y Naturales; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina Fil: Paniego, Norma Beatriz. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Marcucci Poltri, Susana Noemí. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina

In the Yungas of Northwestern Argentina, three endangered species of Cedrela (C. angustifolia, C. saltensis, and C. balansae) follow altitudinal gradients of distribution with contact zones between them. We sampled 210 individuals from 20 populations that spanned most of Cedrela’s geographical range in the Yungas, and used Amplified Fragment Length Polymorphism (AFLP) markers and DNA sequences of the nuclear Internal Transcribed Spacer (ITS) to investigate hybrid zones. Data analyses employed an array of complementary methods, including principal coordinate analyses, Bayesian clustering analyses, maximum likelihood tree-building, and network techniques. Both nuclear molecular systems – AFLP and ITS – provided insights into the evolutionary history of Cedrela in the Yungas in a congruent manner. We uncovered strong support for the occurrence of natural hybridization between C. balansae and C. saltensis. Additionally, we identified hybrid zones in areas of sympatry (at both the Calilegua National Park and the San Andrés farm) and in transition zones from 820 to 1100 meters above sea level (localities of Pintascayo and Acambuco). There was no evidence for hybridization of either C. balansae or C. saltensis with C. angustifolia. The role of hybrid populations in conservation and use of genetic resources in the Yungas were discussed. Fil: Zelener, Noga. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Recursos Biológicos; Argentina Fil: Tosto, Daniela Sandra. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: de Oliveira, Luiz Orlando. Universidade Federal de Viçosa; Brasil Fil: Soldati, María Cristina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Recursos Biológicos; Argentina Fil: Inza, María Virginia. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Recursos Biológicos; Argentina Fil: Fornes, Luis Fernando. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucuman-Santiago del Estero. Estación Experimental Agropecuaria Famaillá; Argentina