title: Degradation of chloroplast DNA during natural senescence of maple leaves.
abstract: The fate of chloroplast DNA (cpDNA) during plastid development and conversion between various plastid types is still not very well understood. This is especially true for the cpDNA found in plastids of naturally senescing leaves. Here, we describe changes in plastid nucleoid structure accompanied with cpDNA degradation occurring during natural senescence of the free-growing deciduous woody species Acer pseudoplatanus L. Natural senescence was investigated using three types of senescing leaves: green (G), yellow-green (YG) and yellow (Y). The extent of senescence was evaluated at the level of photosynthetic pigment degradation, accumulation of starch and plastid ultrastructure. Determination of cpDNA amount was carried out by in planta visualization with 4,6-diamidino-2-phenylindole, by Southern hybridization, and by dot-blot using an rbcL gene probe. During natural senescence, plastid nucleoids undergo structural rearrangements accompanied by an almost complete loss of cpDNA. Furthermore, senescence-associated protein components exhibiting strong binding to an ∼10kbp rbcL-containg cpDNA fragment were identified. This interaction might be important for rbcL expression and Rubisco degradation during the course of natural senescence in trees.
authors.affiliation: Division of Molecular Biology, Ruđer Bošković Institute, Bijenićka cesta 54, HR-10 000 Zagreb, Croatia. fulgosi@irb.hr
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Fulgosi
authors.forename: Marin
authors.initials: M
authors.lastname: Jezic
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Lepedus
authors.forename: Petra Peharec
authors.initials: PP
authors.lastname: Stefanic
authors.forename: Mirna
authors.initials: M
authors.lastname: Curkovic-Perica
authors.forename: Vera
authors.initials: V
authors.lastname: Cesar
mesh_terms: D031002:Acer / Q000737:chemistry* / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D002338:Carotenoids / Q000032:analysis; D016922:Cellular Senescence / Q000502:physiology*; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D002736:Chloroplasts / Q000235:genetics; D002980:Climate; D018742:DNA, Chloroplast / Q000737:chemistry* / Q000235:genetics; D018515:Plant Leaves / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics*; D013213:Starch / Q000378:metabolism
chemical_list: D018742:DNA, Chloroplast; D002734:Chlorophyll; D002338:Carotenoids; C037184:chlorophyll b; D013213:Starch; C101625:RbcL protein, plastid; D012273:Ribulose-Bisphosphate Carboxylase; D000077194:Chlorophyll A