Organogenesis, an important aspect of flowering, helps in understanding key processes of plant development like the formation of floral organs, attainment of reproductive capability, and abscission leading to seed and fruit development. Although abscission, a physiological process involving the shedding of plant organs from the main plant body, may seem opposite to the conventional definition of development, it significantly impacts plant reproductive success and seed dispersal in angiosperms. Furthermore, the petal abscission is dependent on new RNA and protein synthesis, along with cell-wall collapse and cytoplasmic and vacuolar reduction, suggesting that, instead of being a mere catastrophic event, it is an actively controlled cellular process.
To address this, a team of researchers led by Nobutoshi Yamaguchi and Toshiro Ito from the Nara Institute of Science and Technology in Japan used Arabidopsis thaliana Col-0 and mutants/transgenic lines. The study, published in the journal Nature Communications, surpasses conventional boundaries and explores autophagy by utilizing advanced proximity ligation assays (PLA) technology. The researchers employed various experimental methodologies and analyses to investigate the intricate mechanisms governing petal abscission, quantify petal abscission timings, and examine the position of flowers when petals detached. Speaking about the findings, Yamaguchi says, “Our work describes a phytohormone-mediated chromatin state switch that controls spatiotemporal-specific activation of autophagy, leading to terminal cell differentiation for petal abscission.”
Notably, the petal base cells in various plants, like the Japanese morning glory, exhibit distinctive changes in vesicle numbers and cytoplasmic components, hinting at the role of a process called “autophagy” (an intracellular degradation process that allows cells to recycle damaged intracellular components) in petal abscission. However, how these cellular changes are spatiotemporally regulated and lead to autophagy has remained a persistent challenge.
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