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1- MCP efficiency in quality of ornamental peppers
(Horticultura Brasileira, 2018-10) Ribeiro, Wellington S.; Carneiro, Clebson dos S.; França, Christiane de Fátima M.; Pinto, Cleide Maria F.; Lima, Paula Cristina C.; Finger, Fernando L.
1-MCP has been effectively used as an antagonist of ethylene deleterious actions in flowers and ornamental plants. The objective was to evaluate the efficiency of 1-MCP (0.0, 0.5, 1.0 and 1.5 g m-3) in maintaining post-production quality of exogenous ethylene sensitive ornamental pepper. Two commercial varieties were evaluated: Pimenta Colorida and Pimentão Ornamental, both Capsicum annuum. The pre-treatment with 1-MCP, regardless of the applied concentration, was effective in blocking the ethylene action reducing the leaves abscission, flowers and fruits of both genotypes by 100%. Plants pretreated with 1-MCP had postproduction life increased by eight and nine days for Pimenta Colorida and Pimentão Ornamental, respectively. The 1-MCP application at the concentration of 1.0 g m-3 is efficient in maintaining ornamental quality and prolonging the shelf life of Pimenta Colorida and Pimentão Ornamental.
2-Oxoglutarate: linking TCA cycle function with amino acid, glucosinolate, flavonoid, alkaloid, and gibberellin biosynthesis
(Frontiers in Plant Science, 2014-10-05) Araújo, Wagner L.; Martins, Auxiliadora O.; Fernie, Alisdair R.; Tohge, Takayuki
The tricarboxylic acid (TCA) cycle intermediate 2-oxoglutarate (2-OG) is used as an obligatory substrate in a range of oxidative reactions catalyzed by 2-OG-dependent dioxygenases. These enzymes are widespread in nature being involved in several important biochemical processes. We have recently demonstrated that tomato plants in which the TCA cycle enzyme 2-OG dehydrogenase (2-ODD) was antisense inhibited were characterized by early senescence and modified fruit ripening associated with differences in the levels of bioactive gibberellin (GA). Accordingly, there is now compelling evidence that the TCA cycle plays an important role in modulating the rate of flux from 2-OG to amino acid metabolism. Here we discuss recent advances in the biochemistry and molecular biology of 2-OG metabolism occurring in different biological systems indicating the importance of 2-OG and 2-OG dependent dioxygenases not only in glucosinolate, flavonoid and alkaloid metabolism but also in GA and amino acid metabolism. We additionally summarize recent findings regarding the impact of modification of 2-OG metabolism on biosynthetic pathways involving 2-ODDs.
A família Asteraceae em um fragmento florestal, Viçosa, Minas Gerais, Brasil
(Rodriguésia, 2009-10) Ferreira, Silvana da Costa; Carvalho- Okano, Rita Maria de; Nakajima, Jimi Naoki
Este trabalho consiste no levantamento florístico e estudo taxonômico da família Asteraceae, da Estação de Pesquisa, Treinamento e Educação Ambiental, Viçosa, Minas Gerais. Foram amostradas 61 espécies circunscritas a 39 gêneros e 10 tribos. As tribos mais ricas em número de espécies foram Eupatorieae, com 22 espécies, Heliantheae com 11 spp., Astereae, com 10 spp. e Vernonieae com 8 spp. Os gêneros com maior abundância em número de espécies foram Mikania Willd. com oito spp., Baccharis L., com sete spp., Vernonia Schreb. com seis spp e Chromaloena DC. com três spp. Os demais gêneros apresentaram uma ou duas espécies. São fornecidas nesse trabalho chaves analíticas, descrições, ilustrações, comentários taxonômicos e distribuição geográfica para cada espécie.
Ação do flúor dissolvido em chuva simulada sobre a estrutura foliar de Panicum maximum jacq. ( colonião) e Chloris gayana kunth. ( capim- rhodes)- Poaceae
(Acta Botanica Brasilica, 2002-10) Chaves, Alba Lucilvânia Fonseca; Silva, Eldo Antônio Monteiro da; Azevedo, Aristéa Alves; Cano, Marco Antonio Oliva; Matsuoka, Kiyoshi
Panicum maximum e Chloris gayana foram submetidas à chuvas simuladas com soluções de fluoreto de potássio (15mg ml-1) com objetivo de identificar as injúrias causadas pelo flúor (F-), como poluente atmosférico, na estrutura da lâmina foliar e fornecer subsídios para a seleção de características diagnósticas a serem utilizadas na bioindicação. Os principais sintomas foram clorose e necrose, principalmente no ápice e margens das lâminas. Nos cortes transversais, quatro tipos de alterações causadas pelo flúor são relacionadas: redução do número, tamanho e arranjo dos cloroplastos; necrose dos tecidos principalmente nas margens das folhas; erosões na superfície da folha e hipertrofia das células. Em C. gayana, no entanto, não foram observadas as alterações nos cloroplastos e os outros sintomas foram bem mais discretos que em P. maximum. A ocorrência de compostos fenólicos foi registrada pela coloração com fucsina em todas as regiões da lâmina onde foram observadas lesões. Ao microscópio eletrônico de varredura foi observado o achatamento e formação de concavidades nas paredes externas das células. Este experimento confirma a maior sensibilidade de P. maximum ao flúor e revela algumas características anatômicas de C. gayana que, entre outros fatores, podem estar contribuindo para a maior resistência desta espécie a este poluente.
Action of essential oils on sprouting of non - dormant potato tubers
(Brazilian Archives of Biology and Technology, 2018) Finger, Fernando Luiz; Santos, Mirelle Mayana de Sousa; Araujo, Fernanda Ferreira; Lima, Paula Cristina Carvalho; Costa, Lucas Cavalcante da; França, Christiane de Fatima Martins; Queiroz, Matheus da Costa
The breakdown of dormancy and early sprouting is one of the main causes of losses of stored potatoes. Sprouting control becomes important especially when tubers are submitted to long-term storage for further processing by the potato industry. The objective of this work is to evaluate the effect of organic sprout inhibitors, eugenol and menthol essential oils, on the suppression of growth on non-dormant ‘Asterix’ tubers stored at 8 °C. Administration of eugenol and menthol essential oils reduced the number and the length of sprouts during cold storage up to fifty days. Nevertheless, the essential oils stimulated the break of bud apical dominance, stimulating auxiliary buds growth. The effect of the oils was restricted to inducing necrosis of superficial sprout cells without any apparent effect on the skin periderm structure. Repeated applications of oils are necessary to prolong the inhibitory effects of the essential oils on sprouts growth.
Action of abscisic and gibberellic acids on senescence of cut gladiolus flowers
(Bragantia, 2016-10) Costa, Lucas Cavalcante da; Araujo, Fernanda Ferreira de; Lima, Paula Cristina Carvalho; Pereira, Ariana Mota; Finger, Fernando Luiz
The gladiolus flower is classified as insensitive to ethylene. Thus, the signals that initiate senescence are poorly understood. This study evaluated the role of abscisic and gibberellic acids on postharvest senescence of 3 cultivars of cut gladiolus flowers (Gladiolus grandiflora Hort.). Stalks were harvested and placed in test tube containing 100 mL distilled water or an aqueous solution of abscisic acid (100 and 150 µM ABA), gibberellic acid (100 µM GA3), and fluridone (1 mM) for 24 h. Subsequently, flower stalks were placed in a test tube with distilled water, and the following variables were determined: stem longevity, fresh weight change, water uptake rate and transpiration rate during the vase life, as well as membrane stability index and lipid peroxidation in 5 stages of flower development. In another experiment, the florets were removed by cutting down the pedicel. After removal, florets were placed in a beaker containing 10 mL distilled water or the following solutions: 100 or 150 µM ABA; 100 µM GA3; 1 mM fluridone; and 100 µM ABA + 100 µM GA3, followed by immersion in distilled water after 24 h in each treatment. Fresh weight change and transpiration rate of florets were assessed every 24 h. Abscisic acid is involved in the induction of senescence-related events in gladiolus flowers, such as high loss of membrane stability and abnormal flower opening. GA3 regulates the action of ABA in the maintenance of cell membrane and opening of gladiolus flowers.
Action of ethylene, 1-methylcyclopropene and silver thiosulfate in two developmental stages of potted ornamental pepper
(Sociedade Brasileira de Floricultura e Plantas Ornamentais, 2017-08-08) Lima, Paula Cristina Carvalho; Oliveira, Milena Maria Tomaz; Ribeiro, Wellington Souto; Costa, Lucas Cavalcante; Finger, Fernando Luiz
The species of Capsicum genus have great genetic variability with enormous potential for marketing as ornamental potted plants. The exposure at ethylene induces various deleterious responses during plants life cycle, but there are few studies on how the ethylene affects early developmental stages of these ornamental plants. Thus, this study aimed to evaluate the effects of the application of ethylene and ethylene inhibitors, 1-methylcyclopropene (1-MCP) and silver thiosulphate (STS) in two early development stages (seedling or initial flowering) of potted ornamental peppers of the cultivars ‘Calypso’ and ‘MG 302’. Cultivar ‘MG 302’ showed intermediate sensitivity to ethylene, while the cultivar ‘Calypso’ showed complete abscission of leaves when exposed to 10 µl of ethylene for 48 hours in both development stages. Plants treated with 1-MCP showed similar durability to control for both varieties and developmental stages, and the treatment with 1-MCP + ethylene was beneficial only for ‘MG 302’. STS was the most efficient substance in delaying the ethylene, wherein at stage 1 there was no leaf abscission and at stage 2 had much reduced leaf abscission occurred, regardless the cultivar. Treatment with STS + ethylene was efficient only at stage 1 for ‘Calypso’ and at stage 2 for ‘MG 302’. According to the data, cultivars showed different levels of sensitivity to ethylene, ‘Calypso’ is very sensitive and ‘MG 302’ showed intermediate sensitivity. Regardless the cultivar, STS treatment significantly blocked the ethylene action in both development stages and the use of 1-MCP was less efficient
Action of ferric and aluminium ions on the dormancy breakage of Stylosanthes humilis seeds
(Acta Physiologiae Plantarum, 2011-04-05) Ribeiro, Dimas Mendes; Mapeli, Ana Maria; Delatorre, Carla Andréa; Carnelossi, Marcelo Augusto Gutierrez; Barros, Raimundo Santos
Dormancy of scarified seeds of Stylosanthes humilis was broken by acidic Al^3+ and Fe^3+ solutions. Fe^+3-stimulated seeds exhibited a high activity of 1-aminocyclopropane-1-carboxylate (ACC) oxidase and produced great amounts of ethylene, which showed correlated with the germination process. In addition, specific inhibitors of ethylene biosynthesis and action largely depressed the Fe^3+-stimulated germination, leading to the conclusion that the ion broke dormancy by triggering ethylene production by the seeds. By contrast, inhibitors of ethylene biosynthesis and action did not impair germination of Al^3+-stimulated dormant seeds. Moreover, ethylene production and activity of ACC oxidase of Al^3+-treated seeds was substantially decreased by inhibitors of ethylene biosynthesis, but germination kept large. Together these data suggest that ethylene biosynthesis was not required in the chain of events triggered by Al^3+ leading to dormancy breakage. Methyl viologen (MV), a reactive oxygen species-generating compound, broke dormancy of seeds to the same extent as Al^3+ did. Germination of both Al^3+- and MV-stimulated dormant seeds was inhibited by sodium selenate, an antioxidant compound; selenate, however had no effect on germination of Fe^3+-stimulated seeds. Together these data indicate that the mechanisms underlying the germination of Al^3+- and Fe^3+-treated seeds are not the same.
Activity of alternative oxidase and plant uncoupling mitochondrial protein in potato tubers stored at low temperature or submitted to artificial aging
(Brazilian Journal of Plant Physiology, 2004-05) Pinheiro, Hugo Alves; Borges, Regis; Silva, Marco Aurélio Pedron e; Centeno, Danilo Cruz
Potato tubers (Solanum tuberosum L. cv. Binje) were stored at 18 and 4ºC in order to verify changes in mitochondrial metabolism, especially in the activities of the alternative oxidase (AOX) and plant uncoupling mitochondria protein (PUMP). Tubers were also sliced and submitted to artificial aging. The oxygen consumption rate (OCR), respiratory control (RC) and ADP/O ratio for mitochondria obtained after storage at 18ºC were not altered, regardless of the time of storage. Considerable increment in OCR, for both respiratory states 3 and 4, was observed after storing the tubers for five and ten days at 4ºC; and it was accomplished by reductions in RC and ADP/O. The AOX activity was evident after five days at 4ºC, and it was enhanced after ten days of storage at that temperature. No significant changes in PUMP activities were observed after one day at 18ºC or at 4ºC, neither after artificial aging. However, increased swelling of potato mitochondria was observed in the presence of valinomycin and linoleic acid when the tubers were kept at 4ºC for five and ten days. Besides the changes in AOX and PUMP activities, slight alterations in ascorbate peroxidase (APX) and catalase (CAT) activities were observed after storing the tubers at 4ºC for 5 days. The activities of these enzymes were higher after storage at 4ºC for 10 days. The results suggest the combined effect of low temperature and time of exposure in promoting AOX activity, probably as a protective mechanism against cell damage in response to mitochondrial oxidative stress.
Acúmulo e efeitos fitotóxicos do flúor em folhas de boldo-gambá e capim-cidreira utilizadas para chás
(Pesquisa Agropecuária Brasileira, 2010-07) Campos, Naiara Viana; Azevedo, Aristéa Alves; Sant' Anna- Santos, Bruno Francisco
O objetivo deste trabalho foi avaliar o potencial de acúmulo de fluoreto em folhas de boldo-gambá (Plectranthus neochilus) e capim-cidreira (Cymbopogon citratus), determinar o percentual de liberação do poluente por meio da infusão e caracterizar, visual e microscopicamente, os danos foliares causados pelo poluente. Mudas das duas espécies foram submetidas a nevoeiro simulado com fluoreto de potássio. O acúmulo de fluoreto na matéria seca foi mensurado com eletrodo específico em folhas lavadas e não lavadas, infundidas e não infundidas. O percentual de flúor disponibilizado nos chás foi superior para capim-cidreira, embora essa espécie apresente acúmulo de flúor menor que o boldo-gambá. Não foram observados sintomas visuais nas folhas das espécies estudadas, mas ao microscópio eletrônico de varredura, constatou-se a alteração da turgidez das células epidérmicas, ruptura da cutícula e deformação de estômatos e tricomas. O elevado teor de fluoreto nas folhas de C. citratus e P. neochilus e a ausência de sintomas visuais evidenciam que as espécies são tolerantes ao poluente. A lavagem das folhas em água é ineficiente para a remoção do flúor. O acúmulo e a liberação diferenciais de flúor estão relacionados às características morfoanatômicas das espécies analisadas.
Age-related mechanism and its relationship with secondary metabolism and abscisic acid in Aristotelia chilensis plants subjected to drought stress
(Plant Physiology and Biochemistry, 2018-01-12) Rodrigues-Salvador, Acácio; González-Villagra, Jorge; Nunes-Nesi, Adriano; Cohen, Jerry D.; Reyes-Díaz, Marjorie M.
Drought stress is the most important stress factor for plants, being the main cause of agricultural crop loss in the world. Plants have developed complex mechanisms for preventing water loss and oxidative stress such as synthesis of abscisic acid (ABA) and non-enzymatic antioxidant compounds such as anthocyanins, which might help plants to cope with abiotic stress as antioxidants and for scavenging reactive oxygen species. A. chilensis (Mol.) is a pioneer species, colonizing and growing on stressed and disturbed environments. In this research, an integrated analysis of secondary metabolism in Aristotelia chilensis was done to relate ABA effects on anthocyanins biosynthesis, by comparing between young and fully-expanded leaves under drought stress. Plants were subjected to drought stress for 20 days, and physiological, biochemical, and molecular analyses were performed. The relative growth rate and plant water status were reduced in stressed plants, with young leaves significantly more affected than fully-expanded leaves beginning from the 5th day of drought stress. A. chilensis plants increased their ABA and total anthocyanin content and showed upregulation of gene expression when they were subjected to severe drought (day 20), with these effects being higher in fully-expanded leaves. Multivariate analysis indicated a significant positive correlation between transcript levels for NCED1 (9-cis-epoxycarotenoid dioxygenase) and UFGT (UDP glucose: flavonoid-3-O-glucosyltransferase) with ABA and total anthocyanin, respectively. Thus, this research provides a more comprehensive analysis of the mechanisms that allow plants to cope with drought stress. This is highlighted by the differences between young and fully-expanded leaves, showing different sensibility to stress due to their ability to synthesize anthocyanins. In addition, this ability to synthesize different and high amounts of anthocyanins could be related to higher NCED1 and MYB expression and ABA levels, enhancing drought stress tolerance.
Alelopatia de extratos aquosos de canela-sassafrás ( Ocotea odorifera ( Vell.) Rohwer)
(Acta Botanica Brasilica, 2007-07) Carmo, Flávia Maria da Silva; Borges, Eduardo Euclydes de Lima e; Takaki, Massanori
Estudos de alelopatia investigam os efeitos positivos e negativos que metabólitos secundários de plantas, microrganismos ou fungos exercem sobre o desenvolvimento de indivíduos vizinhos. Nesse trabalho foram investigados os efeitos de extratos aquosos de folhas, cascas de tronco e cascas de raízes de canela-sassafrás (Ocotea odorifera (Vell.) Rowher) sobre a germinabilidade das sementes, desenvolvimento do sistema radicular e da parte aérea, teor de clorofila da parte aérea e respiração das células radiculares de plântulas de sorgo (Sorghum bicolor L. Moench cv. Embrapa BR 303). Os extratos foram preparados adicionando o material vegetal seco e moído oriundo de cada órgão à água destilada e deionizada na proporção 1:10 (p/v). Após agitação constante por 24 h, as soluções foram decantadas e filtradas através de papel de filtro sob vácuo, constituindo os extratos testados. Os extratos aquosos de cascas de tronco e de raízes causaram inibição do desenvolvimento do sistema radicular das plântulas de sorgo e a sua parte aérea teve o crescimento estimulado pelo extrato de cascas de raízes. Os extratos de folhas e de cascas de tronco induziram aumento da biomassa fresca do sistema radicular e diminuição significativa do teor de clorofila. Todos os extratos causaram efeitos negativos sobre a respiração radicular das plântulas de sorgo. Concluiu-se que metabólitos secundários da canela-sassafrás causaram alterações metabólicas e morfológicas nas plantas de sorgo e que, portanto, a presença de canela-sassafrás no ambiente pode desencadear efeitos similares sobre outras espécies vegetais na sua vizinhança.
Allometric models for non‐destructive leaf area estimation in coffee (Coffea arabica and Coffea canephora)
(Annals of Applied Biology, 2008-07-29) Antunes, W. C.; Pompelli, M. F.; Carretero, D. M.; DaMatta, F. M.
We aimed to evaluate the currently used allometric models, as well as to propose a reliable and accurate model using non-destructive measurements of leaf length (L) and/or width (W), for estimating the area of leaves of eight field-grown coffee cultivars. For model construction, a total of 1563 leaves were randomly selected from different levels of the tree canopies and encompassed the full spectrum of measurable leaf sizes (0.3–263 cm 2 ) for each genotype. Power models better fit coffee leaf area (LA) than linear models. To validate the model, an independent data set of 388 leaves was used. We demonstrated that the currently used allometric models are biased, underestimating the area of a coffee leaf. We developed a single power model Y= 1⁄4 β◦ x β1 based on two leaf dimensions [LA = 0.6626 (LW) 1.0116 ; standard errors: β◦ = 0.0064, β1 = 0.0019; R2 = 0.996] with high precision and accuracy, random dispersion pattern of residuals and also unbiased, irrespective of cultivar and leaf size and shape. Even when the L (but not width) alone was used as the single leaf dimension, the power model developed still predicted with good accuracy the LA but at the expense of some loss of precision, as particularly found for 8% of the leaves sampled with length-to-width ratios below 2.0 or above 3.0.
Alterações florísticas ocorridas num período de quatorze anos na vegetação arbórea de uma Floresta Estacional Semidecidual em Viçosa-MG
(Revista Árvore, 2002-12-03) Paula, Alessandro de; Silva, Alexandre Francisco da; Souza, Agostinho Lopes de; Santos, Flavio Antonio Maës dos
Estudou-se um fragmento de Floresta Estacional Semidecidual Submontana, localizado no município de Viçosa (de 20o35' a 28o50'S e de 42o45' a 43o00'W), Estado de Minas Gerais, com os objetivos de identificar e analisar as alterações florísticas entre levantamentos realizados em 1984 e 1998. A listagem florística foi determinada a partir de um estudo fitossociológico no qual foi utilizado o método de parcelas contíguas, cobrindo uma área de 1 ha, tendo sido amostrados os indivíduos que apresentassem no mínimo 15 cm de CAP. Em 1998 foram encontradas 94 espécies, distribuídas em 77 gêneros e 32 famílias botânicas. Comparando os levantamentos de 1984 e 1998, constatou-se que dez espécies entraram no perfil, sendo cinco secundárias tardias e cinco secundárias iniciais.
Alternative carbon sources for isoprene Emission
(Trends in Plant Science, 2018-12-01) Araújo, Wagner L.; Souza, Vinícius Fernandes de; Niinemets, Ülo; Rasulov, Bahtijor; Vickers, Claudia E.; Duvoisin Júnior, Sergio; Gonçalves, José Francisco de Carvalho
Isoprene and other plastidial isoprenoids are produced primarily from recently assimilated photosynthates via the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. However, when environmental conditions limit photosynthesis, a fraction of carbon for MEP pathway can come from extrachloroplastic sources. The flow of extrachloroplastic carbon depends on the species and on leaf developmental and environmental conditions. The exchange of common phosphorylated intermediates between the MEP pathway and other metabolic pathways can occur via plastidic phosphate translocators. C1 and C2 carbon intermediates can contribute to chloroplastic metabolism, including photosynthesis and isoprenoid synthesis. Integration of these metabolic processes provide an example of metabolic flexibility, and results in the synthesis of primary metabolites for plant growth and secondary metabolites for plant defense, allowing effective use of environmental resources under multiple stresses.
Amino acid catabolism in plants
(Molecular Plant, 2015-09-15) Hildebrandt, Tatjana M.; Nesi, Adriano Nunes; Araújo, Wagner L.; Braun, Hans-Peter
Amino acids have various prominent functions in plants. Besides their usage during protein biosynthesis, they also represent building blocks for several other biosynthesis pathways and play pivotal roles during signaling processes as well as in plant stress response. In general, pool sizes of the 20 amino acids differ strongly and change dynamically depending on the developmental and physiological state of the plant cell. Besides amino acid biosynthesis, which has already been investigated in great detail, the catabolism of amino acids is of central importance for adjusting their pool sizes but so far has drawn much less attention. The degradation of amino acids can also contribute substantially to the energy state of plant cells under certain physiological conditions, e.g. carbon starvation. In this review, we discuss the biological role of amino acid catabolism and summarize current knowledge on amino acid degradation pathways and their regulation in the context of plant cell physiology.
Análise da estrutura de uma comunidade lenhosa em área de cerrado sensu stricto no município de Senador Modestino Gonçalves, norte de Minas Gerais, Brasil
(Revista Árvore, 2006-08-20) Neri, Andreza Viana; Meira Neto, João Augusto Alves; Silva, Alexandre Francisco da; Martins, Sebastião Venâncio; Batista, Márcio Luiz
Com a finalidade de conhecer a estrutura de uma comunidade arbórea de uma área de Cerrado, fez-se um estudo fitossociológico no Município de Senador Modestino Gonçalves. Para tal foram delimitadas 30 parcelas de 10 x 20m para levantamento dos dados, utilizando-se como critério de inclusão os indivíduos com circunferência do tronco à altura do solo (CAS) = 10 cm. Foram encontradas 91 espécies de 38 famílias. As espécies que se destacaram como as mais importantes foram Qualea grandiflora, Eriotheca pubescens, Caryocar brasiliense, Byrsonima coccolobaefolia, Myrsine guianensis, Qualea parviflora, Dalbergia miscolobium, Stryphnodendron adstringens, Plathymenia reticulata e Lafoensia pacari. Essas 10 espécies representaram 49,32% do VI e 51,26% dos indivíduos amostrados. A área não apresentou espécie com dominância marcante, como mostrou o valor de equabilidade (J'= 0,80). Além de se destacar pela riqueza, o cerrado estudado destacou-se também pelos altos valores de densidade (6.476,67 ind/ha), de área basal (28,93 m2/ha) e pelo alto índice de diversidade (H'=3,61).
Análise dialélica de cafeeiros enxertados, em condições de campo valiação do Carfentrazone-ethyl como dessecante em pré-colheita de sementes de feijão (Phaseolus vulgaris L.)
(Revista Ceres, 2005-05-16) Ferreira, Evander Alves; Santos, Jose Barbosa Dos; Silva, Antonio Alberto da; Silva, Fernanda Monteiro da; Santos, Edson Aparecido dos; Ferreira, Lino Roberto
Conduziu-se esta pesquisa com o objetivo de avaliar a eficácia do herbicida carfentrazone-ethyl como dessecante na cultura do feijoeiro para produção de sementes com antecipação da colheita. Utilizou-se o cultivar Talismã do grupo Carioca, plantado em campo e dessecado em três épocas: aos 25, 30 e 35 dias após o florescimento (DAF), com cinco doses do carfentrazone-ethyl: 0, 10, 30, 60 ou 120 g ha^-1. Em intervalos de dois dias após cada dessecação, quantificou-se a porcentagem de desfolha para ema tratamento. Oito dias após cada aplicação foi realizada a colheita, sendo determinadas a produtividade e o índice de velocidade de emergência (IVE) das sementes. O carfentrazone-ethyl promoveu boa dessecação ao feijoeiro, sendo mais rápida conforme o aumento da dose e dos dias após aplicação. Houve redução da produtividade das sementes, entre 30 e 120 g ha^-1, quando o arfentrazone-ethyl foi aplicado aos 25 DAF, e a maior dose também diminuiu o IVE das ementes. A aplicação de 10 e 30 g ha^-1 de carfentrazone-ethyl, aos 30 DAF, além de não fetar a produtividade e o IVE, antecipou a colheita do feijoeiro em sete dias.
Analysis of a modern hybrid and an ancient sugarcane implicates a complex interplay of factors in affecting recalcitrance to cellulosic ethanol production
(PLOS ONE, 2015-08-07) Poelking, Viviane Guzzo de Carli; Giordano, Andrea; Ricci-Silva, Maria Esther; Williams, Thomas Christopher Rhys; Peçanha, Diego Alves; Ventrella, Marília Contin; Rencoret, Jorge; Ralph, John; Barbosa, Márcio Henrique Pereira; Loureiro, Marcelo
Abundant evidence exists to support a role for lignin as an important element in biomass recalcitrance. However, several independent studies have also shown that factors apart from lignin are also relevant and overall, the relative importance of different recalcitrance traits remains in dispute. In this study we used two genetically distant sugarcane genotypes, and performed a correlational study with the variation in anatomical parameters, cell wall composition, and recalcitrance factors between these genotypes. In addition we also tracked alterations in these characteristics in internodes at different stages of development. Significant differences in the development of the culm between the genotypes were associ- ated with clear differential distributions of lignin content and composition that were not correlated with saccharification and fermentation yield. Given the strong influence of the environment on lignin content and composition, we hypothesized that sampling within a single plant could allow us to more easily interpret recalcitrance and changes in lignin biosynthesis than analysing variations between different genotypes with extensive changes in plant morphology and culm anatomy. The syringyl/guaiacyl (S/G) ratio was higher in the oldest internode of the modern genotype, but S/G ratio was not correlated with enzymatic hydrolysis yield nor fermentation efficiency. Curiously we observed a strong positive correlation between ferulate ester level and cellulose conversion efficiency. Together, these data support the hypothesis that biomass enzymatic hydrolysis recalcitrance is governed by a quantitative heritage rather than a single trait.
Analysis of knockout mutants reveals non-redundant functions of poly(ADP-ribose)polymerase isoforms in Arabidopsis
(Plant Molecular Biology, 2015-10-01) Pham, Phuong Anh; Wahl, Vanessa; Tohge, Takayuki; Souza, Laise Rosado de; Zhang, Youjun; Do, Phuc Thi; Olas, Justyna J.; Stitt, Mark; Araújo, Wagner L.; Fernie, Alisdair R.
The enzyme poly(ADP-ribose)polymerase (PARP) has a dual function being involved both in the poly(ADP-ribosyl)ation and being a constituent of the NAD+ salvage pathway. To date most studies, both in plant and non-plant systems, have focused on the signaling role of PARP in poly(ADP-ribosyl)ation rather than any role that can be ascribed to its metabolic function. In order to address this question we here used a combination of expression, transcript and protein localization studies of all three PARP isoforms of Arabidopsis alongside physiological analysis of the corresponding mutants. Our analyses indicated that whilst all isoforms of PARP were localized to the nucleus they are also present in non-nuclear locations with parp1 and parp3 also localised in the cytosol, and parp2 also present in the mitochondria. We next isolated and characterized insertional knockout mutants of all three isoforms confirming a complete knockout in the full length transcript levels of the target genes as well as a reduced total leaf NAD hydrolase activity in the two isoforms (PARP1, PARP2) that are highly expressed in leaves. Physiological evaluation of the mutant lines revealed that they displayed distinctive metabolic and root growth characteristics albeit unaltered leaf morphology under optimal growth conditions. We therefore conclude that the PARP isoforms play non-redundant non-nuclear metabolic roles and that their function is highly important in rapidly growing tissues such as the shoot apical meristem, roots and seeds.