Revista Brasileira de Fisiologia Vegetalhttps://www.scielo.br/feed/rbfv/2001.v13n2/2020-08-09T08:14:55.354000ZVol. 13 No. 2 - 2001WerkzeugSomatic embryogenesis in goiabeira serrana: genotype response, auxinic shock and synthetic seeds10.1590/S0103-313120010002000012020-08-09T08:14:55.354000Z2020-08-09T06:49:05.776000ZGUERRA, MIGUEL P.DAL VESCO, LIRIO L.DUCROQUET, JEAN PIERRE H.J.NODARI, RUBENS O.REIS, MAURÍCIO S. DOS
<em>Guerra, Miguel P.</em>;
<em>Dal Vesco, Lirio L.</em>;
<em>Ducroquet, Jean Pierre H.j.</em>;
<em>Nodari, Rubens O.</em>;
<em>Reis, Maurício S. Dos</em>;
<br/><br/>
The induction and control of in vitro somatic embryogenesis is dependent of a number of factors. The genotype of the mother plant donor of explants and the kind of auxin play essential roles in conferring embryogenic competence. Once obtained somatic embryos may be encapsulated in alginate originating synthetic seeds that can be stored at low temperatures. Considering this the present work aimed at the assessment of five different genotypes, five periods of 2,4-D shock (20 muM for 1, 2, 4, 8 and 16 weeks) (), and different substances supplemented to sodium alginate to obtain synthetic seeds. Zygotic embryos of Feijoa sellowiana were inoculated in basal LP medium (von Arnold and Erikson, 1981) supplemented with Morel’s vitamins, sucrose (3%) and phytagel (0.2%). The highest rates of somatic embryogenesis induction were observed in the genotypes 50-4 and 101. Shock of two weeks in 2,4-D conferred embryogenic competence in the same levels obtained with the shock of 8 weeks. Histological evaluations revealed the direct origin of the somatic embryos from the epidermic surface of cotyledons. Synthetic seeds containing MS salts and sucrose resulted in higher rates of contamination than capsules free of these substances. KNO3 (100 mM) resulted in the opening of 81.2% of the capsules as compared to 0% of opening in the treatment with water.Influence of mechanical root restriction on gas-exchange of four papaya genotypes10.1590/S0103-313120010002000022020-08-09T08:14:55.354000Z2020-08-09T06:49:05.776000ZCAMPOSTRINI, ELIEMARYAMANISHI, OSVALDO KIYOSHI
<em>Campostrini, Eliemar</em>;
<em>Yamanishi, Osvaldo Kiyoshi</em>;
<br/><br/>
Four papaya genotypes, two from the ‘Solo’ group (Sunrise Solo TJ and Improved Sunrise Solo line 72/12) and two from the ‘Formosa’ group (Tainung 02 and Know You 01) grown in ultisol under field conditions in Macaé, RJ, Brazil, were used in this study. Two different effective depths (ED) were determined in the area using a penetrographer with average soil moisture of 11.2%. The area with ED of 0.35 m with a maximum pressure of 4.12 MPa for penetration was defined as an area with restriction (WR) to root growth, while, the area with minimum ED of 0.60 m and a pressure lower than 2.30 MPa as an area with no restriction (NR). The net CO2 assimilation rate (A), stomatal conductance (g s), leaf temperature (Tl), intercellular partial pressure of CO2 (c i) and intrinsic water use efficiency (IWUE) were evaluated for three consecutive days after irrigation. Mechanical root restriction affected gas exchange of the four papaya genotypes. All genotypes grown in the WR area had lower A, g s and c i and higher Tl than the same genotypes in the NR area. All genotypes grown in the WR area had high IWUE and Sunrise Solo TJ had the highest IWUE.Temperature-dependent germination and endo-beta -mannanase activity in sesame seeds10.1590/S0103-313120010002000032020-08-09T08:14:55.354000Z2020-08-09T06:49:05.776000ZCARVALHO, PATRÍCIA GONÇALVES BAPTISTA DEBORGHETTI, FABIANBUCKERIDGE, MARCOS SILVEIRAMORHY, LAUROFERREIRA FILHO, EDIVALDO XIMENES
<em>Carvalho, Patrícia Gonçalves Baptista De</em>;
<em>Borghetti, Fabian</em>;
<em>Buckeridge, Marcos Silveira</em>;
<em>Morhy, Lauro</em>;
<em>Ferreira Filho, Edivaldo Ximenes</em>;
<br/><br/>
The effects of temperature on germination and endo-beta-mannanase activity in seeds of Sesamum indicum was investigated. The minimum germination temperature (Tmin) lies between 12.8°C and 13.2°C while the maximum temperature (Tmax) is located between 45.5°C and 46°C. Germinabilities are statistically not different from estimated viability (88%) between 18.8°C and 43.2°C. The Mann-Whitney test indicated the interval 31.9°C to 35.1°C as the optimum temperature (Topt) range for germination rate. When seeds incubated at temperatures at or below the Tmin and close to or above the Tmax were transferred to 30°C, those incubated at lower temperatures achieved high germinability. On the other hand, the higher the pre-incubation temperature above Tmax, the lower the germinability achieved near Topt. Seed endosperm cell wall was found to contain mannose as the main monosaccharide. An increase in endo-beta-mannanase activity in the micropylar endosperm prior to seed germination was observed only at supra-optimum temperature.Concentration of photosynthetic pigments and chlorophyll fluorescence of mahogany and tonka bean under two light environments10.1590/S0103-313120010002000042020-08-09T08:14:55.354000Z2020-08-09T06:49:05.776000ZGONÇALVES, JOSÉ FRANCISCO DE CARVALHOMARENCO, RICARDO ANTONIOVIEIRA, GIL
<em>Gonçalves, José Francisco De Carvalho</em>;
<em>Marenco, Ricardo Antonio</em>;
<em>Vieira, Gil</em>;
<br/><br/>
This study was carried out in a plantation of a degraded area in Central Amazon, Brazil, in order to assess environmental light effects on leaf pigment concentrations and chlorophyll a fluorescence in mahogany (Swietenia macrophylla King) and tonka bean (Dipteryx odorata Aubl. Willd). Three-year old saplings were grown in an open site (sun) with maximum radiation of approximately 2000 mumol m-2 s-1 and under the shade of a Ochroma pyramidale (Cav. ex Lam. Urb) canopy. A leaf area index of 2.46 was optically determined for the Ochroma foliage with 13% of full sunlight (maximum radiation about 260 mumol m-2 s-1). Carotenoid and chlorophyll concentrations were spectrophotometrically determined. Initial (Fo), maximum (Fm) and variable fluorescence (Fv) were determined with a portable fluorometer. Chlorophyll concentrations (Chl a, Chl b and Chl tot) on a fresh mass basis were greater in shade leaves than in sun acclimated leaves in both species. On the other hand, when comparisons were made on a per area basis, Chl a concentrations were greater in the sun than in shade leaves of tonka bean. In contrast, Chl b concentrations were higher in the shade environment for this species. No differences were observed in Chl concentrations per unit area in mahogany leaves. Carotenoid concentrations were higher for sun-acclimated leaves of mahogany, both on a per unit area and on a fresh mass basis. In tonka bean, higher carotenoid concentrations in shade leaves were only observed on a fresh weight basis. No differences were found between environments when carotenoid concentrations were expressed as a function of leaf area. Fluorescence variables (Fo, Fm, and Fv) were greater in sun leaves than in shade leaves of mahogany. In contrast, Fv and Fm, but not Fo, values were higher in shade acclimated leaves than in full sunlight-adapted leaves of tonka bean. However, there was a higher Fv/Fm ratio value for tonka bean in sunlight environments. We conclude that these species, classified as mid and late successional species, differ markedly regarding the utilization of photosynthetic pigments, increasing either light harvesting efficiency at low irradiance or protection against photosynthetic machinery damage in higher solar radiation environments.Relação da leitura do clorofilômetro com os teores de clorofila extraível e de nitrogênio na folha de milho10.1590/S0103-313120010002000052020-08-09T08:14:55.354000Z2020-08-09T06:49:05.776000ZARGENTA, GILBERSILVA, PAULO REGIS FERREIRA DABORTOLINI, CLAYTON GIANIFORSTHOFER, EVERTON LEONARDOSTRIEDER, MÉRCIO LUIZ
<em>Argenta, Gilber</em>;
<em>Silva, Paulo Regis Ferreira Da</em>;
<em>Bortolini, Clayton Giani</em>;
<em>Forsthofer, Everton Leonardo</em>;
<em>Strieder, Mércio Luiz</em>;
<br/><br/>
Os métodos utilizados para determinar a quantidade de clorofila na folha requerem destruição de amostras de tecido e muito trabalho no processo de sua obtenção. O recente desenvolvimento do medidor portátil de clorofila, que permite leituras instantâneas do teor relativo de clorofila na folha sem destruí-la, surgiu como uma nova técnica para estimar esse parâmetro. Com os objetivos de avaliar a relação entre leitura do clorofilômetro com os teores de clorofila extraível e de nitrogênio na folha em três estádios de desenvolvimento da planta de milho e de validar o uso do equipamento como parâmetro para estimar o teor relativo de clorofila na folha, conduziu-se um experimento no município de Eldorado do Sul, na região fisiográfica da Depressão Central do Estado do Rio Grande do Sul, no ano agrícola de 1999/2000. Os tratamentos constaram de dois híbridos de milho (Pioneer 32R21 e Premium) e de oito sistemas de manejo de nitrogênio em cobertura. As leituras com clorofilômetro, a extração de clorofila e a determinação do teor de nitrogênio da folha foram realizadas nos estádios de seis a sete folhas, 10 a 11 folhas e de espigamento do milho. Nos dois híbridos, as quantidades de clorofila total e das clorofilas a e b extraíveis foram significativamente relacionadas às leituras do clorofilômetro, nos três estádios de desenvolvimento avaliados. A leitura realizada com clorofilômetro estimou com boa precisão o teor relativo de clorofila na folha de milho, além de apresentar as vantagens de maior rapidez, menor custo e de não implicar em destruição de folhas. No entanto, o clorofilômetro não é muito preciso para avaliação do nível de N na planta nos estádios iniciais de desenvolvimento de milho (seis a sete folhas).Expressão gênica diferencial durante déficit hídrico em soja10.1590/S0103-313120010002000062020-08-09T08:14:55.354000Z2020-08-09T06:49:05.776000ZCASAGRANDE, ELAINE CRISTINAFARIAS, JOSÉ RENATO BOUÇASNEUMAIER, NORMANOYA, TETSUJIPEDROSO, JÚLIOMARTINS, POLYANA KELLYBRETON, MICHÈLLE CLAIRENEPOMUCENO, ALEXANDRE LIMA
<em>Casagrande, Elaine Cristina</em>;
<em>Farias, José Renato Bouças</em>;
<em>Neumaier, Norman</em>;
<em>Oya, Tetsuji</em>;
<em>Pedroso, Júlio</em>;
<em>Martins, Polyana Kelly</em>;
<em>Breton, Michèlle Claire</em>;
<em>Nepomuceno, Alexandre Lima</em>;
<br/><br/>
Tolerância à seca em plantas não é uma característica simples, mas sim um complexo de mecanismos que trabalham em conjunto ou isoladamente para evitar ou tolerar períodos de déficit hídrico. Genótipos que diferem em tolerância ao déficit hídrico devem apresentar diferenças qualitativas e quantitativas na expressão gênica quando submetidos a períodos de seca. Três cultivares de soja (BR-4, BR-16 e MG/BR-46 Conquista), com respostas contrastantes ao déficit hídrico, foram estudadas com o uso da técnica "Differential Display" (DD) para identificar e isolar genes que podem apresentar diferenças de expressão durante períodos de seca entre os genótipos estudados. Um total de 84 fragmentos de DNAc diferencialmente expressos foram detectados. Trinta e cinco fragmentos foram clonados em vetores pGEM-T, onde vinte e oito puderam ser seqüenciados. Comparação das seqüências obtidas com seqüências em bancos de genes mostraram identidade de seqüência com genes conhecidos. Um dos clones, por exemplo, mostrou homologia com um ativador de transcrição encontrado em Arabidopsis thaliana, ao passo que outro clone mostrou-se homólogo a uma subunidade de NADH Desidrogenase de Spinacia oleracea. O ativador de transcrição apresentou-se diferencialmente expresso somente em raízes, e o homólogo à subunidade de NADH Desidrogenase foi expresso somente no genótipo considerado tolerante à seca e somente durante a condição de estresse hídrico. Pelos resultados deste trabalho, foi possível identificar alguns fragmentos potencialmente envolvidos em respostas à condição de seca em soja. Com essas informações, o estudo desses genes pode ser aprofundado, visando à confirmação desses resultados e a auxiliar no desenvolvimento de novos genótipos mais adaptados às condições de seca em soja e possivelmente em outras culturas.Dry matter partitioning differences between shoots and roots in two contrasting genotypes of orchids and their relationship with endogenous levels of auxins, cytokinins and abscisic acid10.1590/S0103-313120010002000072020-08-09T08:14:55.354000Z2020-08-09T06:49:05.776000ZPERES, LÁZARO E. P.MAJEROWICZ, NIDIAKERBAUY, GILBERTO B.
<em>Peres, Lázaro E. P.</em>;
<em>Majerowicz, Nidia</em>;
<em>Kerbauy, Gilberto B.</em>;
<br/><br/>
Epiphytic orchids have been considered an interesting model for plant development and may have unusual features related to the hormonal control of shoot and root growth. In the present experiment we have studied two genotypes of Catasetum fimbriatum Lindl. (Orchidaceae) with an inverse pattern of shoot and root dry matter accumulation. Whereas the CFC1 genotype directs 60% of dry matter towards the shoot system, this same amount is directed towards the root system in the CFC4 genotype. Differences in the endogenous content of cytokinins, IAA and ABA, as well as differences in IAA conjugation and oxidation in shoots and roots were observed in the two genotypes. These differences were correlated with their dry matter partitioning patterns. Thus, the genotype that directed 60% of dry matter towards the root system showed a 20-fold higher auxin accumulation in those organs, while the one that accumulated 60% of dry matter in the shoots showed a 10-fold higher cytokinin accumulation in this plant part. Based on the well established information about auxin and cytokinin biosynthesis, conjugation, oxidation, transport, and effect on organ growth, we have presented an integrative working hypothesis to interpret the data obtained in this study. This working hypothesis may also account for the understanding of the complex relationships involving the hormonal control of the relative growth of shoots and roots in other plant models.Regulation of in vitro somatic embryogenesis with emphasis on to the role of endogenous hormones10.1590/S0103-313120010002000082020-08-09T08:14:55.354000Z2020-08-09T06:49:05.776000ZJIMÉNEZ, VÍCTOR M.
<em>Jiménez, Víctor M.</em>;
<br/><br/>
Different aspects of the in vitro somatic embryogenesis regulation are reviewed in this paper.work. A description of g General aspects, such as terminology, uses, stages of development and factors associated with the somatic embryogenesis, are described. is carried out. Although a brief description ofn the effects of the addition of different plant growth regulators to the culture medium wasis given, the article is centereds itself on the effect that the endogenous hormone concentrations in the initial explants and in the tissue cultures derived from them could play oin the induction and expression of somatic embryogenesis. It is significant that few to emphasize the low amount of systematic studies have been conducted, in this subject, in which different species and hormone groups were compared in cultures with and without embryogenic capacity. Moreover, the lack of correlation between the results presented in different studies the distinct works indicates that the hormone content of the cultures is not the only factor involved.Pectin degradation in ripening and wounded fruits10.1590/S0103-313120010002000092020-08-09T08:14:55.354000Z2020-08-09T06:49:05.776000ZHUBER, DONALD J.KARAKURT, YASARJEONG, JIWON
<em>Huber, Donald J.</em>;
<em>Karakurt, Yasar</em>;
<em>Jeong, Jiwon</em>;
<br/><br/>
Pectin depolymerization during fruit ripening has been shown to be largely due to pectinolytic enzymes, including polygalacturonases (E.C. 3.2.1.15) and pectinmethylesterases (E.C. 3.2.1.11). Studies have shown that these enzymes are not the primary determinants of softening, although participation in texture changes during the late stages of ripening seems evident. Pectin depolymerization differs significantly between various fruit types, notably avocado and tomato, even though levels of extractable PG activity in these fruits are similar. Collective evidence indicates that the activities of some cell wall enzymes are restricted in vivo, with maximum hydrolytic potential expressed only in response to tissue disruption or wounding. In contrast, other enzymes reported to participate in pectin degradation, notably beta-galactosidases/exo-galactanases, exhibit in vitro activity far below that anticipated to be required for the loss of cell wall galactosyl residues during ripening. Factors controlling in vivo hydrolysis have not been fully explored but might include apoplastic pH, cell wall inorganic ion levels, non-enzymic proteins including the noncatalytic beta-subunit and expansins, wall porosity, and steric hindrances. Recent studies of cell wall metabolism during ripening have demonstrated an orderly process involving, in the early stages, cell wall relaxation and hemicellulose degradation followed, in the later stages, by pectin depolymerization. A limited number of studies have indicated that radical oxygen species generated either enzymically or non-enzymically might participate in scission of pectins and other polysaccharides during ripening and other developmental processes. Similar mechanisms might also occur in response to wounding, an event typically followed by an oxidative burst. Cell wall degradation as influenced by physical wounding could be of particular relevance to the deterioration of lightly processed fruits.