As the flowers of Nicotiana mutabilis open and senesce, their petals show a striking color change from
white through pink to red. This was associated with an increase in chalcone synthase (CHS) gene expression
and a substantial rise in petal anthocyanin content. It was also accompanied by up-regulation of
1-aminocyclopropane-1-carboxylic acid oxidase (ACO) transcripts and elevated rates of ethylene production
at the onset of petal wilting. Emission of the fragrant monoterpenoid volatiles 1,8-cineole,
linalool, and terpineol also increased as petals developed pink coloration. The increase in volatile emission
was preceded by a rise in monoterpene synthase (MTS) gene expression. Transcripts of a homologue
of SAG12, a senescence-associated gene encoding a cysteine protease, began to accumulate in petals 3
days prior to visible wilting. Exposure of newly opened white flowers to 1 L L−1 ethylene accelerated
petal coloration, wilting, and induction of SAG12 expression by ca. 1 day while treatment with 500 nL L−1
1-methylcyclopropene (1-MCP), an inhibitor of ethylene action, retarded these processes. The numerous
genetic and experimental tools available for tobacco can readily be applied to this close relative, which
therefore provides an interesting new model for studying ethylene-mediated flower senescence.
As the flowers of Nicotiana mutabilis open and senesce, their petals show a striking color change fromwhite through pink to red. This was associated with an increase in chalcone synthase (CHS) gene expressionand a substantial rise in petal anthocyanin content. It was also accompanied by up-regulation of1-aminocyclopropane-1-carboxylic acid oxidase (ACO) transcripts and elevated rates of ethylene productionat the onset of petal wilting. Emission of the fragrant monoterpenoid volatiles 1,8-cineole,linalool, and terpineol also increased as petals developed pink coloration. The increase in volatile emissionwas preceded by a rise in monoterpene synthase (MTS) gene expression. Transcripts of a homologueof SAG12, a senescence-associated gene encoding a cysteine protease, began to accumulate in petals 3days prior to visible wilting. Exposure of newly opened white flowers to 1 L L−1 ethylene acceleratedpetal coloration, wilting, and induction of SAG12 expression by ca. 1 day while treatment with 500 nL L−11-methylcyclopropene (1-MCP), an inhibitor of ethylene action, retarded these processes. The numerousgenetic and experimental tools available for tobacco can readily be applied to this close relative, whichtherefore provides an interesting new model for studying ethylene-mediated flower senescence.
การแปล กรุณารอสักครู่..
