Balancing trade-offs: Enhanced carbon assimilation and productivity with reduced nutritional value in a well-watered C4 pasture under a warmer CO2-enriched atmosphere.

The concentration of atmospheric CO2 and temperature are pivotal components of ecosystem productivity, carbon balance, and food security. In this study, we investigated the impacts of a warmer climate (+2 °C above ambient temperature) and an atmosphere enriched with CO2 (600 ppm) on gas exchange, antioxidant enzymatic system, growth, nutritive value, and digestibility of a well-watered, managed pasture of Megathyrsus maximus, a tropical C4 forage grass, under field conditions. Elevated [CO2] (eC) improved photosynthesis and reduced stomatal conductance, resulting in increased water use efficiency and plant C content. Under eC, stem biomass production increased without a corresponding increase in leaf biomass, leading to a smaller leaf/stem ratio. Additionally, eC had negative impacts on forage nutritive value and digestibility. Elevated temperature (eT) increased photosynthetic gains, as well as stem and leaf biomass production. However, it reduced P and K concentration, forage nutritive value, and digestibility. Under the combined conditions of eC and eT (eCeT), eT completely offset the effects of eC on the leaf/stem ratio. However, eT intensified the effects of eC on photosynthesis, leaf C concentration, biomass accumulation, and nutritive value. This resulted in a forage with 12% more acid detergent fiber content and 28% more lignin. Additionally, there was a decrease of 19% in crude protein leading to a 15% decrease in forage digestibility. These changes could potentially affect animal feeding efficiency and feedback climate change, as ruminants may experience an amplification in methane emissions. Our results highlight the critical significance of conducting multifactorial field studies when evaluating plant responses to climate change variables.

Genetic characterization of 12 heterologous microsatellite markers for the giant tropical tree Cariniana legalis (Lecythidaceae)

Twelve microsatellite loci previously developed in the tropical tree Cariniana estrellensis were genetically characterized in Cariniana legalis. Polymorphisms were assessed in 28 C. legalis individuals found between the Pardo and Mogi-Guaçu River basins in the state of São Paulo, Brazil. Of the 12 loci, 10 were polymorphic and exhibited Mendelian inheritance. The allelic richness at each locus ranged from 2-11, with an average of 7 alleles per locus, and the expected heterozygosity ranged from 0.07-0.88. These loci showed a high probability of paternity exclusion. The characteristics of these heterologous microsatellite markers indicate that they are suitable tools for investigating questions concerning population genetics in C. legalis.

An efficient and rapid DNA minipreparation procedure suitable for PCR/SSR and RAPD analyses in tropical forest tree species

An efficient and rapid DNA minipreparation modified method for frozen samples was developed for five tropical tree species: Copaifera langsdorffii, Hymenaea courbaril, Eugenia uniflora, Tabebuia roseo alba and Cariniana estrellensis. This procedure that dispenses the use of liquid nitrogen, phenol and the addition of proteinase K, is an adaptation of the CTAB-based DNA extraction method. The modifications included the use of PVP to eliminate the polyphenols, only one chloroform-isoamyl alcohol step and the addition of RNase immediately after extraction with chloroform. The yields of the DNA samples ranged from 25.7 to 42.1 µg from 100 mg leaf tissue. The DNA samples extracted by this method were successfully used for PCR (SSR and RAPD) analyses in these five and other twelve tropical tree species.

Este trabalho teve como objetivo otimizar um protocolo econômico, rápido e eficaz de minipreparação de DNA genômico, para as espécies florestais Copaifera langsdorffii (Óleo de Copaíba), Hymenaea courbaril (Jatobá), Eugenia uniflora (Pitanga), Tabebuia roseo alba (Ipê Branco) e Cariniana estrellensis (Jequitibá Branco). Este método é uma adaptação da técnica de extração CTAB de Doyle e Doyle (1990), o qual consiste principalmente na adição de PVP para eliminar polifenoles, somente uma etapa de extração com clorofórmio-álcool isoamílico e a adição da RNase A imediatamente após a extração com clorofórmio. O método também dispensa o uso de nitrogênio líquido, o uso do fenol e a adição de proteinase K. Os DNAs das espécies florestais extraídos apresentaram alto rendimento e boa qualidade, com rendimento de 25.7 a 42.1 µg de DNA a partir de 100 mg de tecido foliar congelado. Com este protocolo, em apenas 1 dia de trabalho, uma pessoa pode completar o isolamento do DNA de aproximadamente 50 amostras de folhas (dependendo da capacidade da centrífuga). O DNA obtido pode ser usado para métodos de análise baseados em PCR (SSR e RAPD).

Transferability and characterization of microsatellite markers in two Neotropical Ficus species

Microsatellite markers were transferred and characterized for two Neotropical fig tree species, Ficus citrifolia and Ficus eximia. Our study demonstrated that microsatellite markers developed from different subgenera of Ficus can be transferred to related species. In the present case, 12 of the 15 primer pairs tested (80 percent) were successfully transferred to both of the above species. Eleven loci were polymorphic when tested across 60 F. citrifolia and 60 F. eximia individuals. For F. citrifolia, there were 4 to 15 alleles per locus, whereas expected heterozygosities ranged from 0.31 to 0.91. In the case of F. eximia, this was 2 to 12 alleles per locus and expected heterozygosities from 0.42 to 0.87.