Long-term conservation of Tarenaya rosea (Cleomaceae) root cultures: histological and histochemical analyses during cryopreservation using the encapsulation-vitrification technique.

Adventitious root cultures of Tarenaya rosea were successfully cryopreserved using the encapsulation-vitrification technique. Histological analysis revealed useful information on the successive steps of cryopreservation. Coupled with complementary histochemical approaches, these studies provided cellular and tissue descriptions of T. rosea root cultures during cryopreservation and contributed to an understanding of cellular stress responses, as well as characterization of the anatomical pattern of root regeneration. The effects of exposure duration to PVS3 solution (0-120 min), unloading treatment (direct and gradual), and recovery medium (liquid and solid) on recovery of cryopreserved roots were investigated. The highest recovery (91%) after cooling in liquid nitrogen (LN) was reached with PVS3 treatment for 90 min, gradual rehydration in unloading solution, and recovery on solid MS medium. The cryopreserved roots showed high multiplication capacity, which was maintained for up to four subcultures. The effect of cryopreservation on root structure was investigated by histological and histochemical studies. Plasmolysis intensified during exposure to loading and PVS3 solutions, but decreased after unloading treatment. The proportion of intercellular spaces increased progressively throughout the cryopreservation protocol, culminating in root cortex disruption. Histochemical analyses revealed polysaccharides, proteins, and both lipidic and pectic substances in intercellular spaces. The vascular cylinder remained intact, ensuring the formation of new roots from the pericycle, showing that proliferative capacity of cryopreserved roots had not diminished.

A comparative study of cambium histology of Ceiba speciosa (A. St.-Hil.) Ravenna (Malvaceae) under urban pollution.

Air pollution is considered to be one of the main causes of forest decline. The cambium is responsible for increase in tree girth, and its functioning is determined by environmental pressures. This study compared cambium histology of Ceiba speciosa (A. St.-Hil.) Ravenna (Malvaceae) in polluted and preserved sites in the Atlantic Rainforest domain. Samples were obtained during periods of cambial activity and dormancy and were processed and examined according to standard light microscopy techniques. In addition to differences typically observed in cambium during periods of activity and dormancy, the fusiform initials were shorter in trees of the polluted site. Furthermore, cambial rays were shorter, but larger, in the polluted site. It should be noted that all parameters related to cambial rays showed significant differences between the study sites. This is the first report of the effects of pollution on cambial activity in a South American species. The results suggest a tolerance of C. speciosa to pollution and reveal this species to be an important biomarker for environmental monitoring studies.

Somatic embryogenesis and pant regeneration from callus cultures of Cleome rosea Vahl

This paper describes a protocol for the efficient vegetative propagation of Cleome rosea by somatic embryogenesis. Leaf and stem explants from nursery-grown seedlings of C. rosea were cultivated on Murashige and Skoog (MS) medium supplemented with indole-3-acetic acid (IAA), a -naphthaleneacetic acid (NAA), 4-amino-3,5,6-trichloropicolinic acid (picloram) or 2,4-dichlorophenoxyacetic acid (2,4-D). Nodular calli were produced from both explant types in the presence of 4.5 and 9.0 µM 2,4-D. Embryo development and maturation were achieved when calli from stem explants were transferred to media containing a ten-fold reduction of 2,4-D concentration initially used (0.45 and 0.90 µM). Leaf-derived calli did not form embryos with the same treatments. The highest frequency of embryogenic callus formation (85 percent) and number of embryo per callus (13.45 ± 2.8) were achieved during the first subculture on medium supplemented with 0.90 µM 2,4-D. Embryo conversion into plantlets was achieved following transfer to growth regulator-free MS medium solidified with 2 g.L-1 phytagel. An acclimatization rate of 53 percent was found three months after transfer to ex vitro conditions and the recovered plants presented a normal phenotypic aspect.

O trabalho descreve um protocolo para a propagação in vitro de Cleome rosea por embriogênese somática. Explantes foliares e caulinares, obtidos de plantas germinadas sob condições in vivo, foram cultivados em meio de Murashige and Skoog (MS) suplementado com ácido 3-indolacético (AIA), ácido naftalenoacético (ANA), ácido 4-amino-3,5,6-tricloropicolínico (picloram) ou ácido 2,4-diclorofenoxiacético (2,4-D). Calos de aspecto nodular foram produzidos a partir de ambos os tipos de explante na presença de 4,5 e 9,0 μM de 2,4-D. O desenvolvimento e a maturação de embriões somáticos foram alcançados quando calos obtidos de explantes caulinares foram transferidos para meio de cultura suplementado com uma concentração de 2,4-D dez vezes menor do que aquelas utilizadas na indução do processo de calogênese (0,45 e 0,90 μM). Calos derivados de explantes foliares não produziram embriões ao serem submetidos a estes mesmos tratamentos. Os maiores valores de freqüência de calos embriogênicos (85 por cento) e número médio de embriões por calo (13,45±2,8) foram alcançados durante a primeira subcultura em meio suplementado com 0,90 μM de 2,4-D. O processo de conversão dos embriões somáticos em plantas foi observado após transferência dos embriões para meio MS sem suplementação hormonal solidificado com 2 g.L-1 de fitagel. Três meses após a transferência para condições ex vitro a taxa de aclimatização alcançada foi de 53 por cento e as plantas apresentavam um aspecto fenotípico normal.