Photoperiod, water deficit and salt stress in the profile of essential oils in Lippia alba L. cultured in vitro

Lippia alba (Miller) N.E. Brown, conhecida como erva-cidreira brasileira, é uma planta tradicionalmente utilizada pela medicina popular brasileira. Possui importância econômica devido à produção de óleos essenciais aos quais são utilizados para melhoria da qualidade do sono, alívio do estresse, controle de doenças respiratórias, gastrointestinais, anti-inflamatórias e sedativo natural. Podem também ser utilizados no controle biológico contra diversos patógenos e na conservação de alimentos. O objetivo desse estudo foi avaliar o efeito do fotoperíodo, estresse salino e défice hídrico no perfil de óleos essenciais em L. alba cultivada in vitro, utilizando-se de técnicas de análises morfoanatômicas, fisiológicas e moleculares. Desse modo, avaliou-se aspectos anatômicos, o crescimento, metabólitos primários, taxa fotossintética, perfil de óleos essenciais e expressão de genes relacionaods à síntese de óleos essenciais e ao relógio molecular. Foram conduzidos três experimentos: I) Avaliação do efeito de diferentes fotoperíodos (4, 8, 16 e 24 h); II) Avaliação do efeito do estresse salino sob diferentes concentrações de NaCl (0, 30 e 60 mM); e III) Avaliação do efeito do défice hídrico sob diferentes concentrações de PEG [0, 1, 2 e 3% (m/v)] no crescimento, nos metabólitos primários, na taxa fotossintética, no perfil de óleos essenciais e na expressão de genes relacionados à síntese dos óleos essenciais. Os resultados demonstraram que L. alba é uma espécie que apresenta destacada plasticidade fisiológica nos diferentes fotoperíodos com melhor desempenho em dias longos. O melhor desempenho em crescimento, organização anatômica do mesofilo, caule, raízes e feixes, pigmentos fotossintéticos, maior taxa fotossintética e maior síntese de proteínas totais foi sob fotoperíodo de 24 h. A biossíntese de linalol, componente majoritário do quimiotipo BGEN-04, foi aumentada sob fotoperíodo de 24 h, com a redução da expressão de LaGES. O estresse salino afeta negativamente o metabolismo primário de L. alba, em que o crescimento, desenvolvimento e atividades fisiológicas foram comprometidas. O metabolismo secundário foi modulado, tendo aumento nos teores de linalol e redução dos teores de eucaliptol em plantas sob estresse salino mais severo (60 mM). Elevadas concentrações de NaCl podem comprometer a fisiologia das plantas no cultivo in vitro, entretanto, esta é uma espécie que apresenta plasticidade fisiológica sob estresse salino moderado sendo capaz de crescer e desenvolver e não comprometer a via dos monoterpenos e sesquiterpenos. A Lippia alba mostrou-se uma espécie capaz de adaptar em solos com baixa disponibilidade hídrica. O metabolismo primário é afetado com redução do crescimento, área foliar e taxa fotossintética. A limitação hídrica aumentou no conteúdo de aminoácidos e proteínas totais. O metabolismo secundário foi modulado, com aumento nos teores de linalol e redução nos teores de germacreno em plantas sob défice hídrico.Lippia alba (Miller) N.E. Brown is a plant traditionally used by Brazilian popular medicine. It has economic importance due to the production of essential oils, which are used for improve sleep quality, stress relief, control of respiratory and gastrointestinal diseases, anti-inflammatory and natural sedative. They can also be used in biological control against various pathogens and in food preservation.The objective of this study is to evaluate the effect of photoperiod, saline stress and water deficit on the profile of essential oils in L. alba cultivated in vitro, using morphological, physiological and molecular analysis techniques. For this, three experiments were conducted: I) Evaluation of the effect of different photoperiods (4, 8, 16 and 24 h) on anatomy, growth, primary metabolites, photosynthetic rate, essential oils profile and expression of genes related to the synthesis of essential oils and circadian clocks; II) Evaluation of the effect of saline stress under different concentrations of NaCl (0, 30 and 60 mM) in anatomy, growth, primary metabolites, essential oils profile and expression of genes related to the synthesis of essential oils; and III) Evaluation of the effect of the water deficit under different PEG concentrations [0, 1, 2 and 3% (m / v)] on growth, primary metabolites, photosynthetic rate, essential oils profile and related gene expression to the synthesis of essential oils. The results showed that L. alba is a species that presents outstanding physiological plasticity in the different photoperiods with better performance in long days. The best growth performance, anatomical organization of the mesophyll, stem, roots and bundles, photosynthetic pigments, higher photosynthetic rate and higher synthesis of total proteins was under photoperiod of 24 h. The biosynthesis of linalool, a major component of the BGEN-04 chemotype, was increased under a 24-h photoperiod, with reduced expression of LaGES. Saline stress negatively affects the primary metabolism of L. alba, in which growth, development and physiological activities were compromised. Secondary metabolism was modulated, with increase in linalool levels and reduction of eucalyptol contents in plants under more severe salt stress (60 mM). High concentrations of NaCl may compromise the physiology of plants in in vitro culture, however, this is a species that presents physiological plasticity under moderate salt stress being able to grow and develop and not compromise the pathway of monoterpenes and sesquiterpenes. L. alba has been shown to be able to adapt to soils with low water availability. The primary metabolism is affected with reduced growth, leaf area and photosynthetic rate. Water limitation increased in the content of amino acids and total proteins. Secondary metabolism was modulated, with increase in linalool contents and reduction in germacrene levels in plants under water deficit.Fundação de Amparo à Pesquisa do Estado de Minas Gerai

Ethylene responses and ACC oxidase gene expression in Lippia alba (Verbenaceae) chemotypes with varying ploidy levels

Lippia alba (Mill.) N. E. Br ex Britton & P. Wilson is a species of great economic importance due to the medicinal activity conferred by its essential oils. Ethylene (ET) is a gaseous hormone that affects several processes in plant growth and development. This hormone is synthesized through a reaction in which 1-aminocyclopropane-1-carboxylic acid (ACC) is converted to ET by the action of the enzyme ACC oxidase (ACO). The ET activity in three L. alba chemotypes (BGEN-01, triploid; BGEN-02, diploid; and BGEN-42, hexaploid) was evaluated by culturing plants in vitro in the presence of the ET precursor (ACC), scavenger mercury perchloride (MP), the inhibitors aminoethoxyvinylglycine (AVG) and silver thiosulfate (STS), and a CO2-enriched atmosphere. Leaf abscission rate, ET accumulation, and ACO gene expression (LaACO) were investigated. Leaf abscission was higher in BGEN-42, regardless of the precursor/inhibitor. ACC had the highest ET accumulation in BGEN-02 and BGEN-01, whereas BGEN-42 presented lower ET accumulation than the control. MP and AVG were effective in preventing ET production when compared to the control. LaACO was upregulated in BGEN-01 and BGEN-42 treated with ACC and in BGEN-01 treated with STS. In the CO2 enrichment experiments, LaACO expression was higher in BGEN-42 in the treatments without forced ventilation. Thus, the expression of this gene in L. alba can be altered by elevating CO2 levels and also by the addition of ACC. This is the first report of ET interactions in L. alba cultured in vitro

Light quality affects in vitro growth and essential oil profile in Lippia alba (Verbenaceae)

This study evaluated the influence of light quality on growth and essential oil production in three chemotypes of Lippia alba (BGEN-01, BGEN-02, and BGEN-42) grown in vitro. These chemotypes differed both in ploidy and in the predominant essential oil produced. The treatments were fluorescent lamps, white light-emitting diode (LED) bulbs, and blue/red LEDs, all with the same irradiance. After 40 d of culture on hormone-free MS medium, analysis of the essential oil profile and quantitative analysis of growth parameters—plant height, fresh, and dry weight, total chlorophyll, and total carotenoids—were performed. Light quality significantly influenced the in vitro growth of L. alba. Compared to the control, blue/red LEDs induced greater fresh and dry weight in BGEN-01 and BGEN-02 and less in BGEN-42. Photosynthetic pigment levels were higher in plants grown under blue/red LEDs for all chemotypes. Multivariate analysis allowed the identification of different patterns of essential oil production among the treatments. The composition of the volatile compounds varied with light quality and chemotype, with the differences due mainly to the amounts of eucalyptol and linalool. The knowledge of this relationship between light quality and essential oil profile provides a basis for further studies at the genetic level that may elucidate how this regulation works, thereby enabling tailored production of compounds of interest

Light quality in plant tissue culture: does it matter?

The primary issues regarding the lack of protocol reproducibility among laboratories are environmental factors. Light (quantity and particularly quality), is one of those main factors, and studies seldom present the spectral quality of the light sources used. With the advent of light-emitting diode (LED) technology, impressive progress has been made in environmental controls and morphogenetic responses, as directed by the light used in the culture shelves. A wide array of LED lights with different spectra are currently available and light is important in large-scale propagation, especially liquid bioreactor systems. LED technology continues to evolve rapidly and has created additional possibilities. This laboratory has dedicated extensive efforts to implement photoautotrophic propagation, and light is a key component of the system. This review presents relevant topics on the influence of light in various plant tissue culture-based techniques

Ethylene Responses and ACC oxidase Gene Expression in Lippia alba (Verbenaceae) Chemotypes with Varying Ploidy Levels

Lippia alba (Mill.) N. E. Br ex Britton & P. Wilson is a species of great economic importance due to the medicinal activity conferred by its essential oils. Ethylene (ET) is a gaseous hormone that affects several processes in plant growth and development. This hormone is synthesized through a reaction in which 1-aminocyclopropane-1-carboxylic acid (ACC) is converted to ET by the action of the enzyme ACC oxidase (ACO). The ET activity in three L. alba chemotypes (BGEN-01, triploid; BGEN-02, diploid; and BGEN-42, hexaploid) was evaluated by culturing plants in vitro in the presence of the ET precursor (ACC), scavenger mercury perchloride (MP), the inhibitors aminoethoxyvinylglycine (AVG) and silver thiosulfate (STS), and a CO2-enriched atmosphere. Leaf abscission rate, ET accumulation, and ACO gene expression (LaACO) were investigated. Leaf abscission was higher in BGEN-42, regardless of the precursor/inhibitor. ACC had the highest ET accumulation in BGEN-02 and BGEN-01, whereas BGEN-42 presented lower ET accumulation than the control. MP and AVG were effective in preventing ET production when compared to the control. LaACO was upregulated in BGEN-01 and BGEN-42 treated with ACC and in BGEN-01 treated with STS. In the CO2 enrichment experiments, LaACO expression was higher in BGEN-42 in the treatments without forced ventilation. Thus, the expression of this gene in L. alba can be altered by elevating CO2 levels and also by the addition of ACC. This is the first report of ET interactions in L. alba cultured in vitro

Resumos concluídos - Saúde Coletiva

Resumos concluídos - Saúde Coletiv

Resumos concluídos - Saúde Coletiva

Resumos concluídos - Saúde Coletiv