Resistance of progenies of cacao to Ceratocystis wilt

Resistance of progenies of cacao to Ceratocystis wilt Seedlings from open-pollinated progenies of 20 clones of cocoa (Theobroma cacao) were inoculated with the fungus Ceratocystis cacaofunesta, the causal agent of Ceratocystis wilt, and their response was assessed based on the percentage of dead plants. Open pollinated progeny of clones TSH1188 and VB1151 were used as standards for resistance, while CCN51 and SJ02 for susceptibility. Contrasts between these benchmarks and the progenies studied were estimated and evaluated by Dunnett's t test (alpha = 0.05). The progenies showed different responses to C. cacaofunesta, and it was possible to classify them into three groups: resistant (FCB01, CSG70, BOBA01, VB902, TSH1188, VB1151, PS1319 and MAC01), moderately susceptible (HW25, PM02, FA13, PH15, M05 and BJ11) and susceptible (CCN51, FB206, PH16, SJ02, CCN10 and FSU77).

Genetic diversity of polysporic isolates of Moniliophthora perniciosa (Tricholomataceae)

The causal agent of witches' broom disease, Moniliophthora perniciosa is a hemibiotrophic and endemic fungus of the Amazon basin and the most important cocoa disease in Brazil. The purpose of this study was to analyze the genetic diversity of polysporic isolates of M. perniciosa to evaluate the adaptation of the pathogen from different Brazilian regions and its association with different hosts. Polysporic isolates obtained previously in potato dextrose agar cultures of M. perniciosa from different Brazilian states and different hosts (Theobroma cacao, Solanum cernuum, S. paniculatum, S. lycocarpum, Solanum sp, and others) were analyzed by somatic compatibility grouping where the mycelium interactions were distinguished after 4-8 weeks of confrontation between the different isolates of M. perniciosa based on the precipitation line in the transition zone and by protein electrophoresis through SDS-PAGE. The diversity of polysporic isolates of M. perniciosa was grouped according to geographic proximity and respective hosts. The great genetic diversity of M. perniciosa strains from different Brazilian states and hosts favored adaptation in unusual environments and dissemination at long distances generating new biotypes.

EVALUATION OF IN VITRO AND IN VIVO EFFECTS OF SEMIPURIFIED PROTEINASE INHIBITORS FROM THEOBROMA SEEDS ON MIDGUT PROTEASE ACTIVITY OF LEPIDOPTERAN PEST INSECTS

We have characterized in vitro and in vivo effects of trypsin inhibitors from Theobroma seeds on the activity of trypsin- and chymotrypsin-like proteins from Lepidopteran pest insects. The action of semipurified trypsin inhibitors from Theobroma was evaluated by the inhibition of bovine trypsin and chymotrypsin activities determined by the hydrolysis of N-Benzoyl-DL-Arginine-p-Nitroanilide (BAPA) and N-Succinyl-Ala-Ala-Pho-Phe p-Nitroanilide (S-(Ala)2ProPhe-pNA). Proteinase inhibitor activities from Theobroma cacao and T. obovatum seeds were the most effective in inhibiting trypsin-like proteins, whereas those from T. obovatum and T. sylvestre were the most efficient against chymotrypsin-like proteins. All larvae midgut extracts showed trypsin-like proteolytic activities, and the putative trypsin inhibitors from Theobroma seeds significantly inhibited purified bovine trypsin. With respect to the influence of Theobroma trypsin inhibitors on intact insects, the inclusion of T. cacao extracts in artificial diets of velvet bean caterpillars (Anticarsia gemmatalis) and sugarcane borer (Diatraea saccharalis) produced a significant increase in the percentage of adult deformation, which is directly related to both the survival rate of the insects and oviposition.

Large Mammals in an Agroforestry Mosaic in the Brazilian Atlantic Forest

The forest-like characteristics of agroforestry systems create a unique opportunity to combine agricultural production with biodiversity conservation in human-modified tropical landscapes. The cacao-growing region in southern Bahia, Brazil, encompasses Atlantic forest remnants and large extensions of agroforests, locally known as cabrucas, and harbors several endemic large mammals. Based on the differences between cabrucas and forests, we hypothesized that: (1) non-native and non-arboreal mammals are more frequent, whereas exclusively arboreal and hunted mammals are less frequent in cabrucas than forests; (2) the two systems differ in mammal assemblage structure, but not in species richness; and (3) mammal assemblage structure is more variable among cabrucas than forests. We used camera-traps to sample mammals in nine pairs of cabruca-forest sites. The high conservation value of agroforests was supported by the presence of species of conservation concern in cabrucas, and similar species richness and composition between forests and cabrucas. Arboreal species were less frequently recorded, however, and a non-native and a terrestrial species adapted to open environments (Cerdocyon thous) were more frequently recorded in cabrucas. Factors that may overestimate the conservation value of cabrucas are: the high proportion of total forest cover in the study landscape, the impoverishment of large mammal fauna in forest, and uncertainty about the long-term maintenance of agroforestry systems. Our results highlight the importance of agroforests and forest remnants for providing connectivity in human-modified tropical forest landscapes, and the importance of controlling hunting and dogs to increase the value of agroforestry mosaics.

Purification, characterization and structural determination of chitinases produced by Moniliophthora perniciosa

The enzyme chitinase from Moniliophthora perniciosa the causative agent of the witches' broom disease in Theobroma cacao, was partially purified with ammonium sulfate and filtration by Sephacryl S-200 using sodium phosphate as an extraction buffer. Response surface methodology (RSM) was used to determine the optimum pH and temperature conditions. Four different isoenzymes were obtained: ChitMp I, ChitMp II, ChitMp III and ChitMp IV. ChitMp I had an optimum temperature at 44-73ºC and an optimum pH at 7.0-8.4. ChitMp II had an optimum temperature at 45-73ºC and an optimum pH at 7.0-8.4. ChitMp III had an optimum temperature at 54-67ºC and an optimum pH at 7.3-8.8. ChitMp IV had an optimum temperature at 60ºC and an optimum pH at 7.0. For the computational biology, the primary sequence was determined in silico from the database of the Genome/Proteome Project of M. perniciosa, yielding a sequence with 564 bp and 188 amino acids that was used for the three-dimensional design in a comparative modeling methodology. The generated models were submitted to validation using Procheck 3.0 and ANOLEA. The model proposed for the chitinase was subjected to a dynamic analysis over a 1 ns interval, resulting in a model with 91.7% of the residues occupying favorable places on the Ramachandran plot and an RMS of 2.68.