Seed morphoanatomy of the genus Passiflora L. (Passifloraceae) by scanning electron microscopy and light microscopy.

Morphoanatomical analysis of seeds contributes to knowledge of the development of seedlings and identification of species, as well as supporting conservation studies. The conservation of the species belonging to the Passiflora genus is crucial due to of the threats to the genetic resources of these species. Thus, the objective of this study was to morphoanatomically characterize Passiflora seeds, verify possible injuries to the tissues after cryopreservation and thus contribute to the conservation strategies of the species of this genus. Initially, seeds of Passiflora coccinea, P. edulis, P. gibertii, P. maliformis, P. morifolia, P. setacea, P. suberosa, and P. tenuifila collected from the Passion Fruit Active Germplasm Bank of the Embrapa Cassava and Fruits research unit (Embrapa Mandioca e Fruticultura) were analyzed. Then, their length, width and thickness, shape of the base and tip, and ornamentations present on the body and edge of the seeds were evaluated. The seeds of the species were placed in cryotubes and immersed in liquid nitrogen to assess possible cryoinjuries. The tegument and tissues of the seeds were examined by scanning electron microscopy. The seeds had varied biometric data, with average values of 4.63 mm for length, 3.28 mm for width, and 1.51 mm for thickness. Six ornamentation types were observed: reticulate for the species P. coccinea; finely reticulate for P. edulis; foveolate reticulate for P. gibertii and P. setacea; alveolate reticulate for P. maliformis and P. tenuifila; coarsely reticulate for P. morifolia; and falsifoveolate reticulate for P. suberosa. Some seeds suffered tegument cracks due to the freezing in liquid nitrogen, but without physiological damages to the embryo and endosperm. The cryopreservation of the seeds in the presence of the tegument significantly reduced the cryoinjuries caused to the embryo. Cryopreservation can be promising for long-term conservation of passion fruit seeds.

Cryopreservation and germinative behavior of Passiflora spp. seeds.

Cryopreservation is an interesting strategy for the long-term conservation of the seeds of the majority of cultivated plants as well as many of the corresponding wild parents. The objective of this study was to evaluate the response of the seeds of different passion fruit species to cryopreservation, as well as to apply multivariate tools to better understand the germinative behavior after thawing, to support the application and repeatability of these methods with other Passiflora species. Seeds of P. coccinea, P. edulis, P. gibertii, P. maliformis, P. morifolia, P. setacea, P. suberosa and P. tenuifila were submitted to cryopreservation, and after thawing the following variables were analyzed: emergence percentage (%); mean emergence time (days); mean emergence speed (plantlets.day-1); uncertainty (bit); and synchrony (bit). We applied multivariate analysis of variance (MANOVA) and canonical discriminant analysis (CDA) to the data. The seeds of all the species withstood the freezing well, indicating that cryopreservation is a viable alternative for long-term conservation of Passiflora genetic material. The emergence percentage, average emergence speed and average emergence time were the variables that contributed the most to separation of the species in the first canonical discriminant function (Can1). The seeds of the species studied were found to be tolerant to desiccation because they remained viable even with low water content. The results showed that seeds could be cryopreserved successfully both with and without prior desiccation.

Evaluation of Effectiveness of Cement Removal From Implant-Retained Crowns Using a Proposed "Circular Crisscross" Flossing Technique.

Extruded cement during dental implant crown cementation may cause peri-implant diseases if not removed adequately. The purpose of this study was to evaluate the efficiency of removal of cement after cementation of implant crowns using an experimental circular crisscross flossing technique (CCFT) flossing technique, compared to the conventional "C"-shape flossing technique (CSFT). Twenty-four patients rendered 29 experimental and 29 control crowns. Prefabricated abutments were secured to the implant such that the margins were at least 1 mm subgingivally. The abutments were scanned using computer-aided design/computer-aided manufacturing technology and Emax crowns were fabricated in duplicates. Each crown was cemented individually and excess cement was removed using the CSFT and the CCFT techniques. After completion of cementation was completed, the screw access holes were accessed and the crown was unscrewed along with the abutment. The samples were disinfected using 70% ethanol for 10 minutes. Crowns were divided into 4 parts using a marker to facilitate measurement data collection. Vertical and horizontal measurements were made for extruded cement for each control and experimental groups by means of a digital microscope. One-hundred and seventeen measurements were made for each group. Mann-Whitney test was applied to verify statistical significance between the groups. The CCFT showed a highly statistically significant result (104.8 ± 13.66, P < .0001) for cement removal compared with the CSFT (291.8 ± 21.96, P < .0001). The vertical measurements of the extruded cement showed a median of 231.1 µm (IQR = 112.79-398.39) and 43.62 µm (IQR = 0-180.21) for the control and the experimental flossing techniques, respectively. The horizontal measurements of the extruded cement showed a median of 987.1 µm (IQR = 476.7-1,933.58) and 139.2 µm (IQR = 0-858.28) for the control and the experimental flossing techniques, respectively. The CCFT showed highly statistically significant less cement after implant crowns cementation when compared with the CSFT.