Invertase and sucrose synthase activities in coffee plants sprayed with sucrose solution

Abstract

One management practice of which the efficiency has not yet been scientifically tested is spraying coffee plants with diluted sucrose solutions as a source of carbon for the plant. This paper evaluates the effect of foliar spraying with sugar on the endogenous level of carbohydrates and on the activities of invertase and sucrose synthase in coffee (Coffea arabica L.) seedlings with reduced (low) and high (normal) levels of carbon reserve. The concentrations used were 0.5 and 1.0% sucrose, and water as a control. The use of sucrose at 1.0% caused an increase in the concentration of total soluble sugars in depauperate plants, as well as increased the activity of the following enzymes: cell wall and vacuole acid invertase, neutral cytosol invertase and sucrose synthase. In plants with high level of carbon reserve, no increments in total soluble sugar levels or in enzymatic activity were observed. Regardless of treatments or plants physiological state, no differences in transpiration or stomatal conductance were observed, demonstrating the stomatal control of transpiration. Photosynthesis was stimulated with the use of 0.5 and 1.0 % sucrose only in depauperate plants. Coffee seedling spraying with sucrose is only efficient for depauperate plants, at the concentration of 1.0%. Key words: Coffea arabica L., sugar, spray, enzymes ATIVIDADE DE INVERTASES E SACAROSE SINTASE EM PLANTAS DE CAFEEIRO PULVERIZADAS COM SOLUÇÃO DE SACAROSERESUMO: Uma prática cuja eficiência não foi ainda comprovada cientificamente, é a pulverização dos cafeeiros com solução diluída de sacarose, como fonte de carbono para as plantas. Este trabalho visou estudar o efeito da pulverização de açúcar via folha nos teores endógenos de carboidratos e na atividade das enzimas invertases e sacarose sintase em mudas de cafeeiros (Coffea arabica L.) com baixo (baixo) e alto (normal) nível de reservas de carbono. As pulverizações ocorreram nas concentrações de 0,5 e 1% de sacarose utilizandose água como testemunha. A aplicação de sacarose a 1% aumentou a concentração de açúcares solúveis totais (AST) em plantas depauperadas, como também aumentou as atividades das enzimas invertase ácida da parede, invertase ácida do vacúolo, invertase neutra do citosol e sacarose sintase. Em plantas com níveis normais de carboidratos não foi observada nenhuma alteração nos teores dos AST, como também nas atividades de tais enzimas. Independentemente dos tratamentos aplicados e do estado fisiológico das plantas, não foram observadas diferenças na transpiração e na condutância estomática, mostrando, desta forma, o controle estomático da transpiração. A fotossíntese foi estimulada a 0,5% e 1% em plantas depauperadas, o que não aconteceu com plantas normais. A pulverização de sacarose em mudas de cafeeiros só é eficiente tratando-se de plantas depauperadas na concentração de 1%.

Effects of foliar application of gibberellic acid, boric acid and sucrose on noni (M. citrifolia L.) fruit growth and quality

“…High growth rates and yield in sucrose treatments may be due to increased mobile sugar content of the plant, which resulted in more sugar available for investing in fruit growth. Silva et al (2003), showed that foliar sucrose spray increased the endogenous carbohydrates in coffee seedlings that were low on their carbon reserves due to low photosynthesis. Photosynthesis in noni plants at the study site during the experiment was expected to be low due to the considerably low sunshine hours.…”

Insulin-like plant proteins as potential innovative drugs to treat diabetes—The Moringa oleifera case study

“…This makes sense because individuals suffering from diabetes, regardless of whether it is because they do not secrete insulin or do not have adequate insulin signaling, develop seriously deregulated carbohydrate metabolism, accompanied by hyperglycemia and subsequent chronic complications [56]. Similarly, stunted coffee plants presented slight wilting and lower total soluble sugars in comparison to plants grown under optimal physiological photoperiods [57]. In this context, based on the hypothesis that insulin-like proteins in leaves might be associated with photosynthesis, which is a process used by plants and other organisms to convert and store light energy in the form of sugars, it is reasonable to hypothesize that insulin-like proteins have been conserved during plant evolution.…”