In vitro germination and reserve mobilization of Vriesea friburgensis Mez.

Studies on the germination and establishment of plants are key pieces to understanding the reproductive success of plants. This work aimed to describe in vitro germination and reserve mobilization in the bromeliad Vriesea friburgensis through morphological, histochemical, and biochemical analysis. The conditions used in this study for the in vitro germination are adequate. From the third day of in vitro inoculation, a uniform germination of 98% was obtained, exhibiting a high physiological quality of the seeds and a high potential to produce seedlings (94%). There is early reserve mobilization, which began in the imbibition phase. The accumulated reserves in the endosperm cytoplasm are degraded by hydrolytic enzymes provided by the aleurone layer. It is possible that compounds in the cell walls of the endosperm contribute to a lesser extent in mobilization. Additionally, it was observed that starch accumulation in the cotyledon increases when the seedling has formed. Results from this study provide insights for future studies on ecology, seed technology, and conservation in this species. This study contributes to the limited knowledge of the dynamics of reserves during germination and seedling establishment in Bromeliaceae. To the best of our knowledge, this is the first study with this approach in the genus Vriesea.

Ananas ananassoides (Baker) L.B.Sm. a bromeliad from the savanna: seed morpho-anatomy and histochemistry.

Ananas ananassoides (Baker) L.B.Sm. is a wild pineapple, commonly found in the savannas. This study aimed to describe the morpho-anatomy and histochemistry of its seed. The observations were made in the longitudinal and transverse sections, using an optical microscope. The cell arrangement in the seed coat, ripples in the integument, the ratio of embryo size and endosperm amount, and the number of strata in the aleurone layer are anatomical characteristics that may contribute to distinguishing this species. The starch in the endosperm, lipids and proteins in the embryo, constitute the seed's main nutritional reserves. The homogeneous embryo and phenolic compounds present in the seed coat and in the aleurone layer possibly contribute to the dormancy in this species. This study presents information relevant to the taxonomy and physiology of A. ananassoides, which represents contributions to the global knowledge of this species with a high potential as ornamental.

Magnitude and Allele Frequency of Cry1F Resistance in Field Populations of the Fall Armyworm (Lepidoptera: Noctuidae) in Brazil.

Bacillus thuringiensis (Bt) corn producing the Cry1F protein was the first highly efficacious Bt corn deployed against the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in Brazil, but reduced efficacy of this technology against the fall armyworm has been reported in some regions of the country. Here, we surveyed Cry1F resistance allele frequency and susceptibility of eight S. frugiperda populations collected in 2013 from non-Bt fields in different regions of Brazil. In F1 screen experiments, the overall frequency of the Cry1F resistance alleles in Brazilian populations was estimated at 0.24, with 95% credibility interval between 0.18 and 0.25. In concentration-response bioassays, five of the eight populations surveyed exhibited significant resistance levels, which were over 32 times higher than that of the standard susceptible laboratory strain. The estimates of Cry1F resistance allele frequency were positively correlated with those of median effective or lethal concentrations (i.e., EC50 or LC50). These results show that the allelic frequency and the magnitude of Cry1F resistance are high in field populations of S. frugiperda in Brazil, indicating a challenging situation for resistance management.