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Emily Breeze, Elizabeth Harrison,
Stuart McHattie,
Linda Hughes,
Richard Hickman,
Claire Hill,
Steven Kiddle,
Youn-Sung Kim,
Christopher A Penfold,
Dafyd Jenkins, [......],
Alexandra Tabrett,
Roxane Legaie,
Jonathan D Moore,
David L Wild,
Sascha Ott,
David Rand,
Jim Beynon,
Katherine Denby,
Andrew Mead,
Vicky Buchanan-Wollaston
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ABSTRACT: Leaf senescence is an essential developmental process that impacts dramatically on crop yields and involves altered regulation of thousands of genes and many metabolic and signaling pathways, resulting in major changes in the leaf. The regulation of senescence is complex, and although senescence regulatory genes have been characterized, there is little information on how these function in the global control of the process. We used microarray analysis to obtain a high-resolution time-course profile of gene expression during development of a single leaf over a 3-week period to senescence. A complex experimental design approach and a combination of methods were used to extract high-quality replicated data and to identify differentially expressed genes. The multiple time points enable the use of highly informative clustering to reveal distinct time points at which signaling and metabolic pathways change. Analysis of motif enrichment, as well as comparison of transcription factor (TF) families showing altered expression over the time course, identify clear groups of TFs active at different stages of leaf development and senescence. These data enable connection of metabolic processes, signaling pathways, and specific TF activity, which will underpin the development of network models to elucidate the process of senescence.
The Plant Cell 03/2011; 23(3):873-94. · 8.99 Impact Factor
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ABSTRACT: Petal development and senescence entails a normally irreversible process. It starts with petal expansion and pigment production, and ends with nutrient remobilization and ultimately cell death. In many species this is accompanied by petal abscission. Post-harvest stress is an important factor in limiting petal longevity in cut flowers and accelerates some of the processes of senescence such as petal wilting and abscission. However, some of the effects of moderate stress in young flowers are reversible with appropriate treatments. Transcriptomic studies have shown that distinct gene sets are expressed during petal development and senescence. Despite this, the overlap in gene expression between developmental and stress-induced senescence in petals has not been fully investigated in any species. Here a custom-made cDNA microarray from Alstroemeria petals was used to investigate the overlap in gene expression between developmental changes (bud to first sign of senescence) and typical post-harvest stress treatments. Young flowers were stressed by cold or ambient temperatures without water followed by a recovery and rehydration period. Stressed flowers were still at the bud stage after stress treatments. Microarray analysis showed that ambient dehydration stress accelerates many of the changes in gene expression patterns that would normally occur during developmental senescence. However, a higher proportion of gene expression changes in response to cold stress were specific to this stimulus and not senescence related. The expression of 21 transcription factors was characterized, showing that overlapping sets of regulatory genes are activated during developmental senescence and by different stresses.
Journal of Experimental Botany 05/2010; 61(11):2905-21. · 5.36 Impact Factor
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Vicky Buchanan-Wollaston,
Tania Page, Elizabeth Harrison,
Emily Breeze,
Pyung Ok Lim,
Hong Gil Nam,
Ji-Feng Lin,
Shu-Hsing Wu,
Jodi Swidzinski,
Kimitsune Ishizaki,
Christopher J Leaver
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ABSTRACT: An analysis of changes in global gene expression patterns during developmental leaf senescence in Arabidopsis has identified more than 800 genes that show a reproducible increase in transcript abundance. This extensive change illustrates the dramatic alterations in cell metabolism that underpin the developmental transition from a photosynthetically active leaf to a senescing organ which functions as a source of mobilizable nutrients. Comparison of changes in gene expression patterns during natural leaf senescence with those identified, when senescence is artificially induced in leaves induced to senesce by darkness or during sucrose starvation-induced senescence in cell suspension cultures, has shown not only similarities but also considerable differences. The data suggest that alternative pathways for essential metabolic processes such as nitrogen mobilization are used in different senescent systems. Gene expression patterns in the senescent cell suspension cultures are more similar to those for dark-induced senescence and this may be a consequence of sugar starvation in both tissues. Gene expression analysis in senescing leaves of plant lines defective in signalling pathways involving salicylic acid (SA), jasmonic acid (JA) and ethylene has shown that these three pathways are all required for expression of many genes during developmental senescence. The JA/ethylene pathways also appear to operate in regulating gene expression in dark-induced and cell suspension senescence whereas the SA pathway is not involved. The importance of the SA pathway in the senescence process is illustrated by the discovery that developmental leaf senescence, but not dark-induced senescence, is delayed in plants defective in the SA pathway.
The Plant Journal 06/2005; 42(4):567-85. · 6.16 Impact Factor
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ABSTRACT: Petal senescence in many species is regulated by ethylene but some flowers, such as those on the monocotyledonous plant Alstroemeria, var. Rebecca are ethylene insensitive. Changes in gene expression during the post-harvest senescence of Alstroemeria flowers were investigated using several different techniques. Suppressive subtractive hybridization (SSH) was used to obtain cDNA libraries enriched for genes expressed at selected stages of petal senescence. Sequencing of the EST clones obtained resulted in over 1000 sequences that represent approximately 500 different genes. Analysis of the potential functions of these genes provides a snapshot of the processes that are taking place during petal development. Both cell wall related genes and genes involved in metabolism were present at a higher proportion in the earlier stages. Genes encoding metal binding proteins (mostly metallothionein-like) were the major component of senescence enhanced libraries. This limited the diversity of genes identified showing differential expression at the later stages. Changes in the expression of all genes were analysed using microarray hybridization, and genes showing either up or down-regulation were identified. The expression pattern of a selection of genes was confirmed using Northern hybridization. Northern hybridization confirmed the up-regulation of metallothioneins after floral opening, however, this was not detected by the microarray analysis, indicating the importance of using a combination of methods to investigate gene expression patterns. Considerably more genes were up-regulated than down-regulated. This may reflect the need during Alstroemeria petal senescence for the expression of a whole new set of genes involved with degradation and mobilization. The potential uses of expression profiling to improve floral quality in breeding programmes or as a diagnostic tool are discussed.
Plant Biotechnology Journal 04/2004; 2(2):155-68. · 5.44 Impact Factor
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ABSTRACT: Expression of the LSC54 gene, encoding a metallothionein protein, has been shown previously to increase during leaf senescence and cell death. Evidence is presented in this paper to indicate that the extent of LSC54 expression is related to levels of oxidative stress in the tissues. Treatment of Arabidopsis cotyledon and leaf tissues with the catalase inhibitor, 3-amino-1,2,4-triazole, or with silver nitrate result in the enhanced expression of LSC54. Combined treatments with quenchers of reactive oxygen species (ROS), such as ascorbate, tiron and benzoic acid indicated that this induced expression was due to increased levels of ROS. The expression of many other senescence-enhanced genes was also found to be inducible by the increase in ROS. Treatment of plant tissue with 3-amino-1,2,4-triazole, followed by silver nitrate, resulted in protection from the severe damage caused by the silver nitrate treatment and reduced expression of many of the genes examined. However, one gene, encoding a lipid hydroperoxide-dependent glutathione peroxidase, showed increased expression in the protected tissue, which may indicate a role for this enzyme in the protection of plant tissue from oxidative stress. ROS-enhanced expression of at least one of the genes investigated required the presence of the salicylic acid signalling pathway, which was not required for the expression of LSC54.
Journal of Experimental Botany 11/2003; 54(391):2285-92. · 5.36 Impact Factor
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ABSTRACT: Senescence in green plants is a complex and highly regulated process that occurs as part of plant development or can be prematurely induced by stress. In the last decade, the main focus of research has been on the identification of senescence mutants, as well as on genes that show enhanced expression during senescence. Analysis of these is beginning to expand our understanding of the processes by which senescence functions. Recent rapid advances in genomics resources, especially for the model plant species Arabidopsis, are providing scientists with a dazzling array of tools for the identification and functional analysis of the genes and pathways involved in senescence. In this review, we present the current understanding of the mechanisms by which plants control senescence and the processes that are involved.
Plant Biotechnology Journal 02/2003; 1(1):3-22. · 5.44 Impact Factor
