ABSTRACT
Abstract It is a fact that the regions that cultivate the most maize crop do not have fully adequate technologies to measure productivity losses caused by irregularities in water availability. The objective of this study was to evaluate the physiological characteristics of maize hybrids tolerant (DKB 390) and sensitive (BRS 1030) to drought, at V5 growth stage and under water restriction, in order to understand the mechanisms involved in the induction of tolerance to drought by chitosan in contrasting maize genotypes. Plants were cultivated in pots at a greenhouse, and chitosan 100 ppm was applied by leaf spraying. The water restriction was imposed for 10 days and then leaf gaseous exchange and chlorophyll fluorescence were evaluated. The tolerant hybrid (DKB 390) showed higher photosynthesis, stomatal conductance, carboxylation efficiency, electron transport rate, and non-photochemical quenching when chitosan was used. Plants from tolerant genotype treated with chitosan were more tolerant to water stress because there were more responsive to the biopolymer.
Resumo As regiões que cultivam milho como cultura principal ainda não possuem tecnologias adequadas para mensurar as perdas na produtividade decorrentes na disponibilidade irregular de água. O objetivo desse estudo foi avaliar as características fisiológicas de híbridos de milho tolerante (DKB 390) e sensível (BRS1030) à seca, no estádio de crescimento V5 e sob restrição hídrica, para compreender os mecanismos envolvidos na indução de tolerância à seca pela quitosana em genótipos contrastantes. As plantas foram cultivadas vasos na casa de vegetação e a quitosana 100 ppm foi aplicada por pulverização foliar. A restrição hídrica durou 10 dias e foram avaliadas as trocas gasosas e a fluorescência da clorofila. O híbrido tolerante (DKB 390) apresentou maior fotossíntese, condutância estomática, eficiência de carboxilação, taxa de transporte de elétrons e quenching não fotoquímico quando aplicada a quitosana. As plantas do genótipo tolerante tratadas com quitosana foram mais tolerantes ao déficit hídrico porque foram mais responsivas ao biopolímero.
Subject(s)
Zea mays , Chitosan , Photosynthesis , Stress, Physiological , Water , Plant Leaves , DroughtsABSTRACT
Abstract In this study was evaluated the influence of glutamine supplementation on the endogenous content of amino acids, proteins, total phenolics, flavonoids and proanthocyanidins in Bacupari callus. The explants were inoculated in MS medium, MS with half concentration of the nitrogen salts (MS½) and nitrogen-free MS, supplemented with glutamine (5, 10, 30 and 60mM) named as Gln5, Gln10, Gln30 and Gln60. Amino acids and proteins were analyzed after 20, 80 and 140 days and the secondary metabolites on the 140th day. There was no difference in the amino acids on the 20th day. On the 80th day the treatments MS and MS½ presented the lowest levels. On the 140th day MS and MS½ presented the lowest amino acid concentration and Gln10 the highest. Concerning proteins, there was difference only on the 140th day, being the highest concentrations observed in Gln5, and the lowest in MS½ treatment. Total phenolics content was higher in the treatment Gln60 and lowest in MS. Treatments Gln5, Gln10, Gln30 and MS½ were statistically equal. For flavonoids, the highest values occurred in the treatments Gln30, Gln60 and MS½ and the lowest in Gln5, Gln10 and MS. Similarly, for the proanthocyanidins the highest concentrations were observed in treatment Gln60 and the lowest in Gln5 and MS. In conclusion, the treatment with 60mM of glutamine favors the protein accumulation and production of secondary metabolites in Bacupari callus.
Resumo Nesse estudo foi avaliado o efeito da suplementação com glutamina no conteúdo endógeno de aminoácidos, proteínas, fenólicos totais, flavonoides e proantocianidinas em calos de Bacupari. Os explantes foram inoculados em meio MS, meio MS com metade da concentração de dos sais de nitrogênio (MS½) e meio MS sem nitrogênio suplementado com glutamina (5, 10, 30 e 60mM) denominados como Gln5, Gln10, Gln30 e Gln60. Os aminoácidos e as proteínas foram analisados após 20, 80 e 140 dias e os metabólitos secundários no 140° dia. Não houve diferença nos aminoácidos no 20° dia. No 80° dia os tratamentos MS e MS½ apresentaram os menores níveis. No 140° dia, MS e MS½ apresentaram as menores concentrações de aminoácidos e o Gln10 as maiores. A respeito das proteínas, houve diferença apenas no 140° dia, sendo as maiores concentrações observadas nos tratamentos Gln, e as menores no MS½. O conteúdo de fenólicos totais foi maior no tratamento Gln60 e menor no MS. Os tratamentos Gln5, Gln10, Gln30 e MS½ foram estatisticamente iguais. Para os flavonóides, os maiores valores ocorreram nos tratamentos Gln30, Gln60 e MS½ e os menores no Gln5, Gln10 e MS. Da mesma forma, para as proantocianidinas, as maiores concentrações foram observadas no tratamento Gln60 os menores no Gln5 e MS. Em conclusão, o tratamento com 60 mM de glutamina favorece o acúmulo de proteínas e a produção de metabólitos secundários em calos de Bacupari.
Subject(s)
Phenols/analysis , Clusiaceae/metabolism , Clusiaceae/chemistry , Glutamine/metabolism , Glutamine/chemistry , Nitrogen/metabolism , Nitrogen/chemistry , Phenols/chemistry , Plant Proteins/analysis , Plant Proteins/chemistry , Flavonoids/metabolism , Flavonoids/chemistry , Proanthocyanidins/chemistry , Tissue Culture TechniquesABSTRACT
Abstract It is a fact that the regions that cultivate the most maize crop do not have fully adequate technologies to measure productivity losses caused by irregularities in water availability. The objective of this study was to evaluate the physiological characteristics of maize hybrids tolerant (DKB 390) and sensitive (BRS 1030) to drought, at V5 growth stage and under water restriction, in order to understand the mechanisms involved in the induction of tolerance to drought by chitosan in contrasting maize genotypes. Plants were cultivated in pots at a greenhouse, and chitosan 100 ppm was applied by leaf spraying. The water restriction was imposed for 10 days and then leaf gaseous exchange and chlorophyll fluorescence were evaluated. The tolerant hybrid (DKB 390) showed higher photosynthesis, stomatal conductance, carboxylation efficiency, electron transport rate, and non-photochemical quenching when chitosan was used. Plants from tolerant genotype treated with chitosan were more tolerant to water stress because there were more responsive to the biopolymer.
Resumo As regiões que cultivam milho como cultura principal ainda não possuem tecnologias adequadas para mensurar as perdas na produtividade decorrentes na disponibilidade irregular de água. O objetivo desse estudo foi avaliar as características fisiológicas de híbridos de milho tolerante (DKB 390) e sensível (BRS1030) à seca, no estádio de crescimento V5 e sob restrição hídrica, para compreender os mecanismos envolvidos na indução de tolerância à seca pela quitosana em genótipos contrastantes. As plantas foram cultivadas vasos na casa de vegetação e a quitosana 100 ppm foi aplicada por pulverização foliar. A restrição hídrica durou 10 dias e foram avaliadas as trocas gasosas e a fluorescência da clorofila. O híbrido tolerante (DKB 390) apresentou maior fotossíntese, condutância estomática, eficiência de carboxilação, taxa de transporte de elétrons e quenching não fotoquímico quando aplicada a quitosana. As plantas do genótipo tolerante tratadas com quitosana foram mais tolerantes ao déficit hídrico porque foram mais responsivas ao biopolímero.