Genetically Programmed Chloroplast Dedifferentiation as a Consequence of Plastome-Genome Incompatibility in Oenothera

摘要: Comparision of chloroplast from plants with one four plastome types (I, II, III, IV) in the nuclear background Oenothera elata strain Johansen addressed effects plastome-genome incompatibility respect to leaf pigmentation, plastid ultrastructure, chlorophyll a/chlorophyll b ratio, and photosynthetic electron transport. Previous observations plastomes I, IV this have revealed no indications incompatibility, but studies reported here demonstrate that chloroplasts subtle alterations their abilities, particular, deficiencies photosystem II. The well-characterized “hybrid bleaching” AA genotype III involves leaves become bleached center while remaining green at tips, edges, veins. Electron transport assays performed on fractionated tissue same show defects both regions, although latter are more severe. Ultrastructural areas enlarge, thylakoid membranes swollen vesiculated, production new thylakoids is blocked, appearing undergo a programmed senescence. A time course senescence actually reversible dedifferentiation. Alterations composition medium which AA/III seedlings were transferred showed presence auxin can prevent development typical response, rather than bleaching. It proposed differences concentrations plant growth regulators may be responsible for persistence normal near vascular blade edges seasonal fluctuations levels could explain periodic bleaching occurs older plants.