Callus induction in amazonian species of the Theobroma genus

Many works have been done on cocoa (Theobroma cacao) in vitro culture, with few studies being published for other species of the same genus, as cupuassu (T. grandiflorum), whose planted area is increasing expressively, and others that could be used as a source of genes for those with recognized economical importance. Protocols to obtain in vitro somatic embryos from T. cacao,T. grandiflorum,T. speciosum and the hybrid T. grandiflorum x T. obovatum from two sources of explants, staminodes and petals (formed by ligues and cogules) were evaluated, using a primary callus growth medium made of DKW salts, supplemented with 20 g l-1 of sucrose, 250 mg l-1 of glutamine, 200 mg l-1 of myo-inositol, 0.2 mg l-1 of thyamine-HCl; 0.1 mg l-1 of nicotinic acid; 0.2 mg l-1 of glycine; 2 mg l-1 of 2,4-D; 2.2 g l-1 of Gelrite® and the pH adjusted to 5.8. To this media was added different concentrations of thidiazuron (0; 5 and 10 µg l-1). Cultures were maintained at dark for 14 days, at a temperature of 25 ± 2 ºC, and so transferred for the secondary callus growth, made with WPM salts, Gamborg vitamins, 20 g l-1 of sucrose, 2 mg l-1 of 2,4 D; 0.3 mg l-1 of cinetin, 50 ml l-1 of coconut milk, 2.2 g l-1 of Gelrite® and the pH adjusted to 5.8. Callus formation occurred in all species. Somatic embryos were obtained only for T. cacao. Callus formation was influenced by genotype and was higher on staminodes.Vários trabalhos vem sendo desenvolvidos sobre o cultivo in vitro de cacau (T. cacao), mas são raros para a maioria das outras espécies do gênero, como o cupuaçu (T. grandiflorum), cuja a área plantada vem aumentando expressivamente, e outras que poderiam servir de fonte de genes para as espécies economicamente já reconhecidas. Protocolos para obtenção de embriões somáticos in vitro para as espécies T. cacao, T. grandiflorum, T. speciosum e o híbrido T. grandiflorum x T. obovatum foram avaliados a partir de duas fontes de explantes, estaminódios e pétalas (formadas por lígulas e cógulas) cultivados em meio de crescimento primário de calo, consistindo de sais DKW, suplementado com 20 g l-1 de sacarose, 250 mg l-1de glutamina, 200 mg l-1de mio-inositol, 0,2 mg l-1 de tiamina-HCl, 0,1 mg l-1 de ácido nicotínico, 0,2 mg l-1 de glicina, 2 mg l-1 de 2,4-D, 2,2 g l-1 de Gelrite® e pH 5,8. A este meio foram adicionadas diferentes concentrações de tidiazuron (0, 5 e 10 µg l-1). As culturas foram mantidas no escuro por 14 dias, à temperatura de 25 ± 2 ºC, e então transferidas para meio de crescimento secundário de calo, constituído de sais WPM, vitaminas de Gamborg, 20 g l-1 de sacarose, 2 mg l-1 de 2,4 D, 0,3 mg l-1 de cinetina, 50 ml l-1 de água de côco, 2,2 g l-1 de Gelrite® e pH 5,8. A formação de calos ocorreu em todas as espécies. Embriões somáticos foram obtidos somente para T. cacao. A calogênese mostrou-se influenciada pelo genótipo e foi maior nos estaminódios

Mating system and genetic diversity of progenies before and after logging: a case study of Bagassa guianensis (Moraceae), a low-density dioecious tree of the Amazonian forest

The logging of large trees in tropical forests causes a decrease in the density of reproductive individuals, which likely affects the pattern of pollen dispersal and the mating system of the remaining trees in the population. Here, we investigate the impact of logging on mating system and genetic diversity of the low-density, thrip-pollinated, dioecious tree Bagassa guianensis within a 500-ha plot at Tapajós National Forest, Pará State, Brazil. Mating system parameters of the logged population were estimated using mixed-mating model. Six microsatellite loci were used to genotype 232 seeds from ten remnant female trees over three seasons (2006, 2007, and 2008). The data were compared with the mating system of the unlogged population of B. guianensis (18 female trees, 488 seeds) in the same plot. The overall number of alleles found in the open-pollinated progenies decreased after logging (K = 71 before logging and K = 57 after logging, considering the three after logging seasons pooled), as well as the average number of alleles per locus (A = 11.8 and 9.5, respectively). Similarly, the number of private alleles, which is defined in the context of this study as the number of alleles observed in the population exclusively before or after logging, also decreased after logging (15 and 1, respectively). However, the average number of alleles per locus and the observed and expected heterozygosities were not significantly higher before logging than after logging. Logging also did not affect the inbreeding of progenies in the population. Somewhat unexpectedly, the effective number of pollen donors was consistently higher after (Nep = 14.5 in 2006, 8.1 in 2007, and 6.3 in 2008) than before logging (Nep = 3.4), suggesting that the loss of alleles in the population was compensated by the higher heterogeneity in the pollen pool after the removal of the largest trees by logging. Potential causes explaining the patterns found here include the maintenance of large patches of forest around the logged plot and the species’ ability to perform long-distance pollination by airborne thrips. Maintenance of landscape integrity as logged and unlogged forests around the exploited areas is recommended to enhance pollen migration and to avoid long-term losses in genetic diversity. © 2015, Springer-Verlag Berlin Heidelberg

Mating system and genetic diversity of progenies before and after logging: a case study of Bagassa guianensis (Moraceae), a low-density dioecious tree of the Amazonian forest

The logging of large trees in tropical forests causes a decrease in the density of reproductive individuals, which likely affects the pattern of pollen dispersal and the mating system of the remaining trees in the population. Here, we investigate the impact of logging on mating system and genetic diversity of the low-density, thrip-pollinated, dioecious tree Bagassa guianensis within a 500-ha plot at Tapajós National Forest, Pará State, Brazil. Mating system parameters of the logged population were estimated using mixed-mating model. Six microsatellite loci were used to genotype 232 seeds from ten remnant female trees over three seasons (2006, 2007, and 2008). The data were compared with the mating system of the unlogged population of B. guianensis (18 female trees, 488 seeds) in the same plot. The overall number of alleles found in the open-pollinated progenies decreased after logging (K = 71 before logging and K = 57 after logging, considering the three after logging seasons pooled), as well as the average number of alleles per locus (A = 11.8 and 9.5, respectively). Similarly, the number of private alleles, which is defined in the context of this study as the number of alleles observed in the population exclusively before or after logging, also decreased after logging (15 and 1, respectively). However, the average number of alleles per locus and the observed and expected heterozygosities were not significantly higher before logging than after logging. Logging also did not affect the inbreeding of progenies in the population. Somewhat unexpectedly, the effective number of pollen donors was consistently higher after (Nep = 14.5 in 2006, 8.1 in 2007, and 6.3 in 2008) than before logging (Nep = 3.4), suggesting that the loss of alleles in the population was compensated by the higher heterogeneity in the pollen pool after the removal of the largest trees by logging. Potential causes explaining the patterns found here include the maintenance of large patches of forest around the logged plot and the species’ ability to perform long-distance pollination by airborne thrips. Maintenance of landscape integrity as logged and unlogged forests around the exploited areas is recommended to enhance pollen migration and to avoid long-term losses in genetic diversity. © 2015, Springer-Verlag Berlin Heidelberg