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Influence of antiobiotics on NAA- induced somatic embryogenesis in eggplant (Solanum melongena L. cv. Embil)
88-95.Views:302The influence of increasing concentrations of naphthaleneacetic acid and the antibiotics cefotaxime, timentin, kanamycin, and hygromycin on eggplant (Solantun melongena L. cv. Embil) somatic embryogenesis was investigated. Cotyledon explants were excised from 16 to 20 days old in vitro grown seedlings. NAA promoted somatic embryogenesis, although its concentrations had no influence on the mean number of embryos. Callusing decreaSed significantly with increasing NAA concentrations. Morphogenesis was stopped with 50 to 100 mg L-1 kanamycin and 7.5 to 15 mg L-1 hygromycin. Although early globular embryos were observed up to 15 mg L-1, further embryo development was inhibited at 10 mg L-1. Interestingly, cefotaxime (250 and 500 mg L-1) promoted a marked effect on enhancing fresh weight of calli, accompanied by decrease in embryo regeneration, whereas timentin concentrations (150 and 300 mg L-1) did not affect embryo differentiation as compared to the control treatment.
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Left, right, up and downstage: leaves and lateral roots histological trait prospection for drought tolerance in commercial Coffea arabica cultivars
44-65.Views:568The climate change and water deficit challenges plant producers all over the world, and have consequences to coffee production and quality. In this research we have approached anatomical traits from vegetative organs of 13 Coffea arabica genotypes, selected based on their contrasting behavior to water deficit. Leaf blade, petiole and primary root cross sections were evaluated, and the epidermal, fundamental, and vascular tissues descriptive anatomy, histometric and histochemistry examined. Despite all plants were in the same environment (CEPC/EPAMIG, Patrocínio, MG, Brazil), there were differences among the genotypes and groups of more tolerant and more susceptible accesses. Petiole cross section, vascular tissue and phloem and cambium; and percentage of stele, pericycle and phloem and cambium in primary roots exhibited differences among the contrasting genotypes, highlighting an inborn association of vascular tissue and other features with water deficit resistance. This association was observed in the mild to medium correlations among vascular tissue, epidermis, phloem and cambium in roots and petioles. Possible relation of qualitative traits such as the lignification of root epidermis, lipidic substances in outer cortical cell layers, and area/number of cell layers in the cortex are approached as possible traits in the seek for water deficit tolerance in C. arabica.
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Linking bark anatomy to Eucalyptus Physiological Disorder (EPD) in commercial clones
73-87.Views:380Abiotic stresses trigger the Eucalyptus Physiological Disorder (EPD) which poses a threat to planted and native stands. This research seeks links between eucalyptus bark histological features and EPD, in which the descriptive bark anatomy and histochemistry are approached. Barks from 5-year eucalyptus trees, from commercial clones of E. grandis, E. urophylla and its hybrids, were collected at breast height (DBH), and 50% and 75% of the commercial height, and evaluated. The eucalyptus bark consisted of a periderm (or rhytidome) and a secondary phloem with conspicuous solitary sieve tube elements (STE). The outer bark revealed a secondary phloem with collapsed STE, whereas its inner counterpart displayed non-collapsed STEs. A region crowded with calcium oxalate (CaOx) crystals in axial parenchyma, covering the non-collapsed and partially overlapped collapsed secondary phloem, was observed. Eucalyptus barks exhibited similar anatomical organization at DBH, 50% and 75% of the commercial height, irrespective of expected EPD phenotype or scores. Notwithstanding, there are qualitative differences that are associated with the proportion of non-collapsed phloem and phloem with crystals, which were higher in the tolerant clones and in trees with score 0. The more resistant clones or samples with lower EPD scores exhibited a higher proportion of the regions of living phloem, phloem with CaOx crystals, and non-collapsed phloem. These results support the hypothesis that an increased proportion of STE collapse will occur concurrently with elevated EPD scores and are the basis for an ongoing histometric approach.
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Ultrastructural and biochemical aspects of normal and hyperhydric eucalypt
61-69.Views:426Hyperhydricity 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.
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Resistance gene Sw-5 of tomato confers resistance to TCSV in Solanum melongena
41-47.Views:280Eggplants transformed with Sw-5 gene, regenerated by organogenesis and somatic embryogenesis, were resistant to the Tomato chlorotic spot virus, while wild plants did present systemic infection. TO plants were selfed and the segregation analysis of T1 and T2 generation indicated the existence of one or more insertion sites. Southern blot analysis confirmed one or two independent insertions in T2 plants. Different lesions associated with the insertion number were observed in TI and T2 plants. T2 plants with two copies displayed faster hypersensitive reactions and characteristic necrotic lesions that contrasted with slower responses and necrotic ring lesions in plants with one copy. These results suggest that the Sw-5 confers resistance to tospovirus in transgenic eggplants and that the resistant phenotype depends on the number of transgene copies.
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Study of genetic transformation efficiency via organogenesis and embryogenesis in eggplant (Solanum melongena L. cv. Embti): effects of co-culture, temperature and kanamycin and hygromycin-based selection procedures
15-23.Views:358The effects of kanamycin and hygromycin-based selection and co-culture temperature ranging from 22 to 28 °C upon eggplant transformation efficiency were evaluated. Both morphogenic pathways, somatic embryogenesis and organogenesis, were adopted using cotiledonary and hypocotyl explants, respectively. Somatic embryos were recovered in the presence of both antibiotics, although lesser escapes were observed in hygromycin-supplemented medium. Indeed, selection provided by this antibiotic was more efficient compared to kanamycin, nevertheless, shoot regeneration was not observed with hygromycin. Significant difference on the frequency of cotiledonary explants displaying callus (FEC) was observed as embryogenesis was concerned, although a higher number of embryos was observed in hygromycin selective media. The frequency of explants presenting callus (FEC), embryos (FEE) and shoots or buds (FERG) did not differ statistically for the tested co-culture temperatures, although higher regenerant number was observed at 24 °C.
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Organogenesis in eggplant (Solanum melongena L. cv. Embu) as affected by antibiotics and growth regulators
76-82.Views:413The 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.
