Rapid determination of seed vigor based on the level of superoxide generation during early imbibition

Xuejun Liu, Da Xing, Lingling Li, Lingrui Zhang
2007 Photochemical and Photobiological Sciences  
It has been reported that a large amount of reactive oxygen species (ROS) is produced during seed imbibition and this ROS is related to seed vigor. To make this physiological mechanism clear, we have used 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo(1,2-a)pyrazin-3-one (MCLA) as a sensitive and physiologically compatible probe for the determination of superoxide anion (O 2 • − ) production in vivo. Our results showed that dry rice (Oryzae sativa L.) seed embryo cells possessed the capacity
more » ... ssed the capacity to generate O 2 • − . Conversely, the O 2 • − production of seed embryo cells was inhibited by quinacrine (QA) and diphenylene iodonium (DPI), two specific inhibitors of NADPH oxidase, and O 2 • − induced MCLA-mediated chemiluminescence was also blocked by superoxide dismutase (SOD). Additionally, O 2 • − -production ability increased dramatically in a NADPH-dependent way in the plasma membrane protein abstract from rice seed embryo cells, whereas SOD and the inhibitors mentioned above suppressed O 2 • − production. These preliminary results suggested that rice seeds contained intrinsic NADPH oxidase activity. To validate this conclusion, dichlorofluorescein (DCF) fluorescence staining was used (observed under a laser scanning microscope, LSM) to reflect the in situ assessment of O 2 • − -generation. The position of O 2 • − production located at the plasma membrane. Additionally the ability to synthesize O 2 • − was activated directly by calcium ions. These observations are in accord with the character of NADPH oxidase catalyzed O 2 • − -generation. All these results indicated that NADPH oxidase contribute to O 2 • − production and release to the outside. We concluded that NADPH oxidase plays an intrinsic role as an NADPH sensor, so, measuring the O 2 • − one can monitor the NADPH concentration, which is an index of seed vigor. Therefore the O 2 • − generation during early imbibition can serve as a rapid measurement of seed vigor.
doi:10.1039/b704337f pmid:17609770 fatcat:323cba4cxjafnp4grbawhzafhi