Defects in a proteolytic step of light-harvesting complex II in anArabidopsis stay-green mutant,ore10, during dark-induced leaf senescence

Abstract

During dark-induced leaf senescence (DIS), the non-functional stay-green mutant orelO showed delayed chlorophyll (Chl) degradation and increased stability in its light-harvesting complex II (LHCII). These phenomena were closely related to the formation of aggregates that mainly consisted of terminal-truncated LHCII (Oh et al., 2003). The orelO mutant apparently lacks the protease needed to degrade the truncated LHCII. In wild-type 0NT) plants, protease was found in the thylakoid fraction, but not the soluble fraction. A similar experiment using dansylated LHCII revealed that the protease degraded both WT and ore10 LHCII, indicating that its stability in orelO perhaps did not result from a defect in the LHCII polypeptides themselves. Although protease activity was not present in non.senesced WT leaves, it was induced during DIS. It also was possible to diminish the high level of protease present in the thylakoids through high-salt washing, suggesting that this enzyme is extrinsically bound to the outer surface of the stromaexposed thylakoid regions.

Increased Stability of LHCII by Aggregate Formation during Dark-Induced Leaf Senescence in the Arabidopsis Mutant, ore10

“…Our recent results suggest that the proteolytic activity is inducible, not present in non-senesced WT leaves (Oh et al 2003). Therefore, the former possibility is unlikely, if we accept that ore10 is a single-gene mutant, because the non-senesced leaves of homozygous recessive ore10 plants are wrinkled and smaller than normal.…”

Identification of a Novel Chloroplast Protein AtNYE1 Regulating Chlorophyll Degradation during Leaf Senescence in Arabidopsis

“…Mutants, with Chl degradation being disturbed but other senescence-associated processes not being significantly affected, have been reported in diversified species (Thomas and Stoddart, 1975;Guiamét et al, 1990;Akhtar et al, 1999;Cha et al, 2002;Guiamét et al, 2002;Luquez and Guiamét, 2002;Oh et al, 2003Oh et al, , 2004Efrati et al, 2005). But only quite recently have the identities of corresponding genes been indicated in two crop species, Festuca pratensis and rice (Oryza sativa; Armstead et al, 2006;Hö rtensteiner, 2006).…”

An Evaluation of the Basis and Consequences of a Stay-Green Mutation in thenavel negraCitrus Mutant Using Transcriptomic and Proteomic Profiling and Metabolite Analysis

“…Those identified to date span a broad taxonomic range, including members of the Gramineae (durum wheat [Triticum durum; Spano et al, 2003]; Festuca pratensis [Thomas, 1987]; rice [Oryza sativa; Cha et al, 2002;Jiang et al, 2007;Kusaba et al, 2007;Park et al, 2007]), Arabidopsis (Arabidopsis thaliana; Woo et al, 2001;Oh et al, 2003Oh et al, , 2004Ren et al, 2007), and the Leguminosae (soybean [Glycine max;Guiamét andGiannibelli, 1994, 1996;Luquez and Guiamét, 2002]; Phaseolus vulgaris [Ronning et al, 1991;Bachmann et al, 1994]; pea [Pisum sativum; Armstead et al, 2007;Sato et al, 2007]). A stay-green mutant phenotype has also been reported in tomato (Solanum lycopersicum) fruits (the green flesh mutant; Cheung et al, 1993;Akhtar et al, 1999) and pepper (Capsicum annuum; mutant chlorophyll retainer; Efrati et al, 2005;Roca and Mínguez-Mosquera, 2006).…”

“…After genetic and biochemical analyses, it was concluded that the mutant was affected in either the PaO gene or a specific regulator of this gene. Although biochemical lesions in PaO have been reported for several stay-green mutants (Hö rtensteiner, 2006), other types of mutations can also result in stay-green phenotypes, such as Chl b reductase in the rice nyc1 mutant and genes involved in light-harvesting complex protein II (LHCPII) proteolysis in the ore9 (Woo et al, 2001) and ore10 (Oh et al, 2003(Oh et al, , 2004) Arabidopsis stay-green mutants. In addition, it has been shown that RNA interference-mediated knockdown of a soybean senescence-associated receptor-like kinase confers a stay-green phenotype .…”