After different pre-culturing period (12, 23 or 34 days) on ½ MS medium with 1 mg l-1 paclobutrazol, 1 mg l-1 N6-benzyladenine and 0.1 mg l-1 1- naphthaleneacetic acid , 3 groups of Narcissus poeticus ssp. radiiflorus bulb scales were kept on the same medium without hormones. The results were evaluated monthly and the final one happened after...7 month. The best results were achieved due to the shortest pre-culturing period (12 days; Group 1), with 4.9 bulblets and 4.54% hyperhydricity. The result of the second treatment (pre-culturing period of 23 days; Group 2) was not different significantly but the number of bigger bulblet were higher (4.54 bulblets). After the longest pre-culturing period (34 days; Group 3), the number of bulblets was low (3.68) and more hyperhydricity (18.18%) was detected. The highest number of roots (13.91) was observed in this group
very likely due to the strong after-effect of paclobutrazol.
The influence of antibiotics (cefotaxime, timentin, kanamycin and hygromycin) and growth regulators (indolacetic acid and 6-benzylaminopurine) was evaluated on eggplant organogenesis. Solanum melongena hypocotyl segments (6 to 10 mm length), taken from 16 to 20-days in vitro grown seedlings, were used as explants. The basic medium was...composed by MS salts, Gamborg vitamins and 2% sucrose, solidified with agar 0.8% and pH adjusted to 5.7±0.2. Morphogenesis was impaired at 50 to 100 mg L-I kanamycin and 7.5 mg L-1 hygromycin. Both Timentin and cefotaxime reduced the frequency of regenerating explants meanwhile hyperhydricity was not affected. A decrease in root regeneration was observed with increasing cefotaxime concentrations, although, timentin had no effect on root regeneration, as compared to the control treatment. Interestingly, the number of adventitious roots was more noticeable at 0.25 mg L-I IAA plus 0.5 mg L-1 BAP. However, if just IAA was added led to higher number of regenerated roots compared to other treatments.
Hyperhydricity was observed throughout in vitro multiplication phase of a Eucalyptus grandis clone. Ultrastructural approach of tissue and cell differentiation, izoenzyme patterns, binding protein (BiP) expression, and pigment content were performed. Hyperhydric tissues showed a reduction in cell wall deposition, reduction of...membranous organelles, higher cell vacuolation, and more intercellular spaces than its normal counterpart. Additionally, several vesicles were present in hyperhydric cells suggesting the occurrence of organelle autophagy by autophagic vacuole. Lower pigment content, intercellular spaces on the epidermis and the induction of a molecular chaperone (BiP) were observed in hyperhydric phenotype. Evidences of schizolysigenous process of intercellular space formation are compatible with a stress condition. Although plastoglobulli were observed in normal and hyperhydric chloroplasts, they were more evident in the normal ones. Abnormal stomata also reflected a disruptive situation and morphogenesis disturbances which would difficult plant acclimatization. Further observation of the epidermis ultrastructure allows us to conclude that the presence of intercellular spaces on its surface may be constraining the recovery and development of hyperhydric plants. Similarly to BiP, other proteins such as esterase (EST), acid phosphatase (ACP), malate dehydrogenase (MDH) and peroxidase (PDX) are possible to be used as stress markers in in vitro conditions. Our results confirm earlier findings about negative effects of hyperhydricity on in vitro plant morphogenesis and ultrastructure, which in eucalypt is associated with a stressful condition contributing to lower propagation ratios.