Genes associated with opening and senescence of Mirabilis jalapa flowers.
A modest ethylene climacteric accompanies flower senescence in Mirabilis jalapa L., and exogenous ethylene accelerates the process. However, inhibitors of ethylene action and synthesis have little effect on the life-span of these ephemeral flowers. Treatment with alpha-amanitin, an inhibitor of DNA-dependent RNA synthesis, substantially delays the onset of senescence. This effect falls linearly between 7 h and 8 h after the start of flower opening. Subtractive hybridization was used to isolate transcripts that were up- and down-regulated during this critical period. Eighty-two up-regulated and 65 down-regulated transcripts were isolated. The genes identified encode homologues of a range of transcription factors, and of proteins involved in protein turnover and degradation. Real-time quantitative RT-PCR was used to examine expression patterns of these genes during flower opening and senescence. Genes that were identified as being down-regulated during senescence showed a common pattern of very high expression during floral opening. These genes included a homologue of CCA1, a 'clock' gene identified in Arabidopsis thaliana and an aspartyl protease. Up-regulated genes commonly showed a pattern of increase during the critical period (4-9 h after opening), and some showed very strong up-regulation. For example, the abundance of transcripts encoding a RING zinc finger protein increased >40 000 fold during the critical period.
Xu
Xinjia
X
Department of Plant Sciences, University of California, One Shields Avenue, Davis, CA 95616, USA.
Gookin
Tim
T
Jiang
Cai-Zhong
CZ
Reid
Michael
M
D000546:Amanitins / Q000494:pharmacology; D016922:Cellular Senescence / Q000187:drug effects / Q000235:genetics*; D005030:Ethylenes / Q000037:antagonists & inhibitors / Q000494:pharmacology; D035264:Flowers / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D039282:Mirabilis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D009693:Nucleic Acid Hybridization; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D000546:Amanitins; D005030:Ethylenes; D010937:Plant Growth Regulators; D010940:Plant Proteins; C036216:ethylene