title: Chlorophyll in desiccated seeds of a euhalophyte, Suaeda physophora, and its significancy in plant adaptation to salinity during germination.
abstract: The seed cotyledons of a euhalophyte, Suaeda physophora, were found to be dark green. The pigment extracted from the cotyledons was proved to be chlorophyll for the absorption spectra curve of extracts the same as that for leaves. Photosynthetic oxygen-exchanging could be detected after the seeds were moistened for 6 h. Microstructure of organelles in cotyledons of ungerminated seeds was detected by transmission electron microscopy. Histochemical pigmentation was used to investigate the degree of damage on the membrane of radicles. A xerophyte, Haloxylon persicum, whose cotyledons of desiccated seeds also contain chlorophyll was used as a comparative species. The results showed that S. physophora maintained the ultra-structure of chloroplasts, the integrity of plasma membranes of radicles kept much better than that of H. persicum, which showed the great adaptability to salinity of the euhalophyte even at the seed-germination stage. Seeds were incubated in 0 and 700 mmol/L NaCl for 10 days in darkness at 20 degrees C, then ungerminated seeds in NaCl solution were transferred to deionised water and reincubated for another 8 days and was recorded the germination recovery. Dry seeds moistened with deionised water germinated gradually in the dark and germination was maximal after 3 or 4 d. Seeds at 700 mmol/L NaCl for 10 d and transferred back to deionised water germinated abruptly, most seeds germinated in one day and photosynthesis was also detected. It is concluded that recovery germination of S. physophora ensured the seeds could germinate rapidly after salinity declines, for example under the mild but transitory favorable edaphic condition in early spring. Photosynthesis function in seeds might also promoted radicle growth and seedling establishment.
authors.affiliation: College of Resource and Environmental Science, China Agricultural University, Beijing 100094, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: ShiRong
authors.initials: S
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Song
authors.forename: ChenXi
authors.initials: C
authors.lastname: Wu
authors.forename: ChangYan
authors.initials: C
authors.lastname: Tian
authors.forename: Gu
authors.initials: G
authors.lastname: Feng
mesh_terms: D000222:Adaptation, Physiological; D019663:Chenopodiaceae / Q000196:embryology / Q000502:physiology*; D002734:Chlorophyll / Q000032:analysis*; D002736:Chloroplasts / Q000648:ultrastructure; D018525:Germination; D008854:Microscopy, Electron; D012639:Seeds / Q000737:chemistry*; D012965:Sodium Chloride
chemical_list: D002734:Chlorophyll; D012965:Sodium Chloride