<b>Antioxidative enzymes of <i>Cucumis sativus</i> seeds are modulated by <i>Leucaena leucocephala</i> extracts

Abstract

ABSTRACT.This study aimed to analyze oxidative stress produced in cucumber seeds and seedlings when exposed to aqueous extract from dried leaves of leucaena, as well as its effect on the germination behavior, early growth and the antioxidant enzymes activity. It was evaluated the percentage, the speed index, the average time, the frequency and germination synchronization, the root length and shoot, as well as the catalase and peroxidase enzymes activity. There was no significant inhibitory effect of the leaf extracts on the germination percentage. However, there was delay in the seeds germination, as the extract proportion increased. A stimulatory effect of the extract compared to the shoot length was observed, however the root growth was significantly reduced. The catalase activities had a peak at 24 hours after soaking the seeds, however, the activities were reduced in seedlings. The peroxidase activity was low in the seeds and increased in the seedlings at 168 hours after immersion. The results suggest that there was oxidative stress due to allelochemicals present in the leaves extracts from leucaena, verified by germination and initial growth changes, causing alterations in the plants rootlets.Keywords: allelopathy, reactive oxygen species, antioxidant enzymes.Enzimas antioxidativas de sementes de Cucumis sativus são moduladas por extratos de Leucaena leucocephala RESUMO. Este trabalho objetivou analisar o estresse oxidativo produzido em sementes e plântulas de pepino quando submetidas a extrato aquoso de folhas secas de leucena bem como, seu efeito sobre o comportamento germinativo, crescimento inicial e atividade de enzimas antioxidantes. Foram avaliadas a porcentagem, índice de velocidade, tempo médio, frequência e sincronização da germinação, comprimento de raiz e parte aérea e atividade das enzimas catalase e peroxidase. Não houve efeito inibitório significativo dos extratos sobre a porcentagem de germinação. No entanto, houve atraso na germinação das sementes, à medida que se aumentou a proporção do extrato. Foi observado efeito estimulatório do extrato em relação ao comprimento da parte aérea, porém o crescimento da raiz foi reduzido significativamente. As atividades da catalase tiveram pico às 24 horas de embebição das sementes, tendo sido reduzido nas plântulas. No entanto, a atividade da peroxidase foi baixa nas sementes e teve aumento nas plântulas, às 168 horas após a embebição. Os resultados sugerem que houve estresse oxidativo devido aos aleloquímicos presentes nos extratos foliares de leucena, verificado pelas alterações na germinação e de crescimento inicial, o que causou alterações nas radículas das plântulas.Palavras-chave: alelopatia, espécies reativas de oxigênio, enzimas antioxidantes.

Extratos de espécies florestais como alternativa no controle de tiririca (Cyperus rotundus)

“…A corda-de-viola teve o parâmetro comprimento de raiz afetado pelos extratos e o picão-preto foi prejudicado em sua germinação e no comprimento de raiz. Analisando o efeito do extrato de leucena sobre a germinação e o crescimento inicial de sementes e plântulas de pepino (Cucumis sativus), Ribeiro et al (2017) observaram que houve um retardo na germinação das sementes e uma diminuição do comprimento da radícula das plântulas em função do estresse oxidativo causado pelos aleloquímicos do extrato, comprovando o potencial alelopático da leucena.…”

Evaluation of the allelopathic effect of wheat and redroot pigweed on growth indices and antioxidant system activity in intercropping

“…Allelochemicals in low concentrations affect receptor plants and stimulate them to improve the ability of their antioxidant enzyme activity to resist oxidative stress (Ming et al 2020). Previous research has confirmed the effect of allelopathic compounds on the enzymatic activity of CAT, SOD, APX, and POD in various plants, including Vigna unguiculata L., tomatoes, rice seedlings, Cucumis sativus L., and cucumber (Zuo et al 2012;Ahmad et al 2013;Siddique and Ismail 2013;Oyeniyi et al 2016;Ribeiro et al 2017).…”

Allelopathic Effects of Aqueous Extracts of Sorghum (Sorghum bicolorL. Moench) on the Early Seedling Growth of Sesame (Sesamum indicumL.) Varieties and Selected Weeds

“…e extracts were stored in sealed plastic bottles in a refrigerator at 4°C until further use [23]. e 10% wv −1 stock solution was diluted with distilled water to make 2.5%, 5.0%, and 7.5% solutions prior to use [24]. e experiment for sesame was a factorial experiment with two factors, namely, sesame variety and sorgaab concentration.…”

“…is suggests that exposure to allelochemicals responsible for sorghum allelopathy has a stimulatory effect on plant defense system. Ribeiro et al [24] and Zhou et al [36] reported that plants are capable of developing defense mechanisms in the form of reactive oxygen species (ROS) removal systems. Highly reactive superradicals such as hydroxyl (OH * ) and hydroperoxyl (H 2 O * ) cause damage to the cell membrane structure, damage to DNA and proteins, lipid peroxidation, and damage to the photosynthetic apparatus [35,37].…”