Characterization of the Pepper CaPAO Gene for Defense Response to Salt-induced Leaf Senescence

Pheophorbide a oxygenase (PAO) is a vital enzyme in the chlorophyll catabolism pathway and is involved in leaf senescence. Previous studies have indicated the function of PAO during cell death, but its involvement in leaf senescence is not well understood. Huai-Juan Xiao of the Northwest A&F University and Henan Agricultural University in China, together with colleagues studied the function of PAO.

A PAO gene, CaPAO, was isolated from pepper (Capsicum annuum L.) and expression was found to be higher in leaves than roots, stems, and flowers. It was upregulated by abscisic acid, methyl jasmonate, and salicylic acid. A gene silencing technique was used to silence the CaPAO gene in pepper plants. After 3 days of high salt treatment, the chlorophyll breakdown of CaPAO-silenced pepper plants was retarded.

The gene was expressed in tobacco plant after a week of salt treatment. The leaves of transgenic tobacco exhibited extreme chlorosis and chlorophyll content was significantly lower than in control plants. Results suggest that CaPAO gene plays an important role in responses to salt-induced leaf senescence.

For more information on the study, read the article in BMC Biotechnology.