methyl-jasmonate and salicylhydroxamic-acid

Two-line hybrid rice systems represent a new technical approach to utilizing the advantages of rice hybrids. However, the mechanism underlying the male sterile-line fertility transition in rice remains unclear. Peiai 64S (PA64S) is a photoperiod- and thermo-sensitive genic male sterile (PTGMS) line in which male sterility manifests at an average temperature above 23.5 °C under long-day (LD) conditions. Nongken 58S (NK58S) is a LD-sensitive genic male sterile (PGMS) rice that is sterile under LD conditions (above 13.75 h-day). In contrast, D52S is a short-day (SD)-PGMS line that manifests male sterility under SD conditions (below 13.5 h-day). In this study, we obtained fertile and sterile plants from all three lines and performed transcriptome analyses on the anthers of the plants. Gene ontology (GO) analysis suggested that the differentially expressed genes identified were significantly enriched in common terms involved in the response to jasmonic acid (JA) and in JA biosynthesis. On the basis of the biochemical and molecular validation of dynamic, tissue-specific changes in JA, indole-3-acetic acid (IAA) levels, gibberellin (GA) levels, and JA biosynthetic enzyme activities and expression, we proposed that JA could play a pivotal role in viable pollen production through its initial upregulation, constant fluctuation and leaf-spikelet signaling under certain fertility-inducing conditions. Furthermore, we also sprayed methyl jasmonate (MEJA) and salicylhydroxamic acid (SHAM) on the plants, thereby achieving fertility reversal in the PGMS lines NK58S and D52S, with 12.91-63.53% pollen fertility changes. Through qPCR and enzyme activity analyses, we identified two key enzymes-allene oxide synthase (AOS) and allene oxide cyclase (AOC)-that were produced and upregulated by 20-500-fold in PGMS in response to spraying; the activities of these enzymes reversed pollen fertility by influencing the JA biosynthetic pathway. These results provide a new understanding of hormone interactions and networks in male-sterile rice based on the role of JA that will help us to better understand the potential regulatory mechanisms of fertility development in rice in the future.

Topics: Acetates; Cyclopentanes; Fertility; Gene Expression Profiling; Gene Expression Regulation, Plant; Intramolecular Oxidoreductases; Oryza; Oxylipins; Plant Proteins; Pollen; Salicylamides; Signal Transduction

Methyl-jasmonate (MJ)-treated hairy roots of Daucus carota L. were used to study the influence of alternative oxidase (AOX) in phenylpropanoid metabolism. Phenolic acid accumulation, as well as total flavonoids and lignin content of the MJ-treated hairy roots were decreased by treatment with salicylhydroxamic acid (SHAM), a known inhibitor of AOX. The inhibitory effect of SHAM was concentration dependent. Treatment with propyl gallate (PG), another inhibitor of AOX, also had a similar inhibitory effect on accumulation of phenolic acid, total flavonoids and lignin. The transcript levels of two DcAOX genes (DcAOX2a and DcAOX1a) were monitored at selected post-elicitation time points. A notable rise in the transcript levels of both DcAOX genes was observed preceding the MJ-induced enhanced accumulation of phenolics, flavonoids and lignin. An appreciable increase in phenylalanine ammonia-lyase (PAL) transcript level was also observed prior to enhanced phenolics accumulation. Both DcAOX genes showed differential transcript accumulation patterns after the onset of elicitation. The transcript levels of DcAOX1a and DcAOX2a attained peak at 6hours post elicitation (hpe) and 12hpe, respectively. An increase in the transcript levels of both DcAOX genes preceding the accumulation of phenylpropanoid-derivatives and lignin showed a positive correlation between AOX activity and phenylpropanoid biosynthesis. The results provide important new insight about the influence of AOX in phenylpropanoid biosynthesis.

Topics: Acetates; Cyclopentanes; Daucus carota; Dose-Response Relationship, Drug; Flavonoids; Gene Expression Regulation, Plant; Hydroxybenzoates; Lignin; Mitochondrial Proteins; Oxidoreductases; Oxylipins; Phenols; Phenylalanine Ammonia-Lyase; Plant Growth Regulators; Plant Proteins; Plant Roots; Propanols; Propyl Gallate; RNA, Messenger; RNA, Plant; Salicylamides

The role of jasmonic acid was studied in biotransformation of (--)-isopiperitenone to (--)-7-hydroxyisopiperitenone using alpha suspension cells were treated with (--)-isopiperitenone, mRNA of a cytochrome P450 was induced in a similar time-course pattern as the biotransformation shown in a previous study (Park et al., 1997). The induction of P450 mRNA and the biotransformation of (--)-isopiperitenone were increased by methyl jasmonate, but decreased by salicylhydroxamic acid, and inhibitor of jasmonic acid synthesis. These results suggest that the biotransformation involves the induction of P450 which is mediated by jasmonic acid as a signaling molecule.

Topics: Acetates; Antifungal Agents; Biotransformation; Cell Extracts; Cell Wall; Cells, Cultured; Cyclopentanes; Cytochrome P-450 Enzyme Inhibitors; Cytochrome P-450 Enzyme System; Gene Expression Regulation; Monoterpenes; Oxylipins; Plant Cells; Plant Growth Regulators; Plants; RNA, Messenger; Salicylamides; Terpenes; Yeasts