Production of reactive oxygen species in Dalbergia nigra seeds under thermal stress

Abstract

-Seed germination is dependent on abiotic factors, temperature being one of the main ones, whose influence causes seed damage under extreme conditions. The aim of the present study was to investigate the effect of different temperatures during germination of D. nigra seeds and their physiological and biochemical implications. We assessed germination percentage and production of superoxide anion (O 2 -) and hydrogen peroxide (H 2 O 2 ) in seeds subjected to temperatures of 5, 15, 25, 35 and 45 ºC for different periods of time. Hydration is promoted at 45 ºC and inhibited at 5ºC, without germination in either, whereas it is minimal at 15 °C and at a maximum level at 25 °C. Superoxide production increases at higher temperatures (25 and 35 ºC) after 72 hours of hydration, coinciding with the beginning of radicle protrusion. Production of hydrogen peroxide decreases at all temperatures, except for 5 ºC, with values near each other at temperatures of 15, 25, and 35 ºC, where there was radicle protrusion. Termos para indexação: floresta, fisiologia, bioquímica, jacarandá-da-bahia.

ALTERAÇÕES FISIOLÓGICAS E BIOMÉTRICAS EM SEMENTES DEMelanoxylon brauna Schott DURANTE A GERMINAÇÃO EM DIFERENTES TEMPERATURAS1

“…A produção de peróxido de hidrogênio pode estar envolvida nos danos causados à germinação, conforme foi observado no eixo embrionário de sementes de M. brauna, em que as atividades das enzimas superóxido Germinação (%) A temperatura de 40 ºC, todavia, resultaria na desnaturação de enzimas importantes no processo metabólico ou, mesmo, na produção de substâncias reativas de oxigênio, conforme verificado por Matos et al (2014) em sementes de Dalbergia nigra, em que a produção de superóxido aumentou nas temperaturas mais altas, em que não houve germinação, e nas de M. brauna, conforme Flores et al (2014), em que houve aumento das atividades da enzimas superóxido dismutase e catalase, indicando a presença de superóxido e superóxido de hidrogênio.…”

Enzymatic activity in braúna seeds subjected to thermal stress

“…Seed germination is a fundamental stage in the plant life cycle (MEI & SONG, 2010) and consists of a complex and orderly set of physiological and biochemical events that result in the rupture of the integument by the primary root, which then continues to develop until a new plant is formed (BEWLEY et al, 2013 Among the factors affecting germination, temperature plays a key role, as it determines the capacity and rate of seed germination (ZAMITH et al, 2013), assists in overcoming primary and/ or secondary dormancy (MONDONI et al, 2012), affects the speed of water absorption by the seeds (ATAÍDE et al, 2014), and controls the rate of the biochemical reactions that determine the entire process (MATOS et al, 2014).…”