Pollination induces autophagy in petunia petals via ethylene

• Published in: Journal of experimental botany 2013-02, Vol.64 (4), p.1111-1120
• Main Authors: Shibuya, Kenichi, Niki , Tomoko, Ichimura, Kazuo
• Format: Article
• Language: English
• Subjects: analogs & derivatives; anatomy & histology; antagonists & inhibitors; Autophagy; Biological and medical sciences; Biological Transport; Biology and morphogenesis of the reproductive apparatus. Photoperiodism, vernalisation; Cadaverine; Cadaverine - analogs & derivatives; Cadaverine - metabolism; Cellular senescence; corolla; electron microscopy; ethylene; ethylene inhibitors; Ethylene production; Ethylenes; Ethylenes - antagonists & inhibitors; Ethylenes - metabolism; Flowers; Flowers - genetics; Flowers - metabolism; Flowers - ultrastructure; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; genes; Genes, Plant; genetics; mesophyll; Mesophyll Cells; Mesophyll Cells - metabolism; Messenger RNA; metabolism; Microscopy, Electron, Transmission; Multigene Family; Nitrogen; nitrogen content; nutrients; Ovaries; Petals; Petunia; Petunia - anatomy & histology; Petunia - genetics; Petunia - metabolism; Petunia hybrida; Plant Cells; Plant Cells - metabolism; plant ovary; Plant physiology and development; Plant Proteins; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Pollination; RESEARCH PAPER; RNA, Messenger; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Plant; RNA, Plant - genetics; RNA, Plant - metabolism; senescence; Senescence and abscission; ultrastructure; Up-Regulation; Vegetative and sexual reproduction, floral biology, fructification; Vegetative apparatus, growth and morphogenesis. Senescence
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/ers395

Autophagy is one of the main mechanisms of degradation and remobilization of macromolecules, and it appears to play an important role in petal senescence. However, little is known about the regulatory mechanisms of autophagy in petal senescence. Autophagic processes were observed by electron microscopy and monodansylcadaverine staining of senescing petals of petunia (Petunia hybrida); autophagy-related gene 8 (ATG8) homologues were isolated from petunia and the regulation of expression was analysed. Nutrient remobilization was also examined during pollination-induced petal senescence. Active autophagic processes were observed in the mesophyll cells of senescing petunia petals. Pollination induced the expression of PhATG8 homologues and was accompanied by an increase in ethylene production. Ethylene inhibitor treatment in pollinated flowers delayed the induction of PhATG8 homologues, and ethylene treatment rapidly upregulated PhATG8 homologues in petunia petals. Dry weight and nitrogen content were decreased in the petals and increased in the ovaries after pollination in detached flowers. These results indicated that pollination induces autophagy and that ethylene is a key regulator of autophagy in petal senescence of petunia. The data also demonstrated the translocation of nutrients from the petals to the ovaries during pollination-induced petal senescence.