Post-hypoxic Oxidative Stress in Aging Pea Seeds: I. Hypoxia Development during Imbibition

Content Provider	Semantic Scholar
Author	Veselova, T. V. Veselovsky, Vladimir A.
Copyright Year	2009
Abstract	During seed transition from quiescence to metabolic activity and subsequent germination, orthodox seeds become sensitive to stress. Aging seeds become particularly sensitive to stress conditions and during storage, seeds undergo aging that deteriorates their quality. Each seed lot contains strong seeds, weak seeds, and dead seeds, but dry seed quality cannot be assessed prior to germination. Nevertheless, airdry pea seeds differing in germinability can be divided into three fractions using the method of room temperature phosphorescence (RTP): fraction I, alive high-quality seeds which will produce normal seedlings; fraction II, alive but weak seeds which will produce morphologically abnormal seedlings or will not germinate at all; and fraction III, dead seeds. The imbibition patterns of fraction I and fraction II seeds were compared during germination. The water uptake during imbibition was higher in the fraction II seeds than in those of fraction I. A higher respiration rate and greater limitation of oxygen diffusion by seed coats in fraction II seeds induced oxygen deficiency, which can be considered as hypoxic conditions for embryo. In order to assess the hypoxia level, we developed a non-intrusive luminescent method based on endogenous porphyrin phosphorescence of seeds. Result showed that hypoxia did not appear in fraction I seeds. In fraction II pea seeds, the hypoxia starts to develop after 12-16 h imbibition. When oxygen deficiency enhanced, alive seeds did not germinate as they died due to suffocation during imbibition. If the level of oxygen deficiency was not high (<50 arbitrary units (aU) of porphyrin phosphorescence) and radicles protruded, the emerging seedlings exhibit various morphological defects. Since hypoxia did not impair DNA replication (2C-4C) prior to radicle protrusion, it did not directly contribute to morphological abnormalities in seedlings.
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Language	English
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Content Type	Text
Resource Type	Article