BioProject

Chlorophyll (Chl) degradation is an important process during leaf senescence, bud breaking and fruit ripening. More...

Chlorophyll (Chl) degradation is an important process during leaf senescence, bud breaking and fruit ripening. Chlorophyll catabolic pathway has been intensively studied and nearly all the enzymes involved in the pathway are characterized. However, regulatory mechanism of the pathway is largely unknown at the molecular level. In this study, we performed a yeast one-hybrid screening using a library composed only of transcription factor cDNAs to search for factors controlling expression of the chlorophyll catabolic genes. We identified a common regulator, ANAC046, that directly binds to the promoter regions of NON-YELLOW COLORING 1, STAY-GREEN 1 (SGR1), SGR2, and pheophorbide a oxygenase. Transgenic plants overexpressing ANAC046 exhibited an early senescence phenotype with lower chlorophyll content as compared with the wild-type plants, while loss-of-function mutants exhibited a delayed senescence phenotype with higher chlorophyll content. Microarray analysis of ANAC046 showed that not only chlorophyll catabolic genes but also senescence-associated genes were positively regulated by ANAC046. Here, we demonstrate that ANAC046 is a novel positive regulator of Arabidopsis leaf senescence and exerts its effect through controlling the expressions of Chl catabolic genes and senescence-associated genes. Overall design: Transcriptomes of leaf of ANAC046-overexpression plant (50 days after seed sawing), seedling of ANAC046-SRDX-overexpression plant (5 days after dark treatment), and seedling of ANAC046-knockout plant (5 days after dark treatment) were measured together with their respective wild-type controls. Less...