Autophagy, a major catabolic pathway in eukaryotic cells, plays critical roles in the recycling of proteins and lipids, and is involved in many developmental processes. It plays important roles in pollen maturation and required for tapetal programmed cell death (PCD), postmeiotic anther development and nutrient supply to the pollens in rice (Kurusu et al. 2014). In this paper, we introduce an in vivo imaging technique to analyze the dynamics of autophagy in rice tapetum by expressing GFP-ATG8, a marker for autophagosomes under the control of tapetum-specific promoters. The results from imaging analyses including 3-dimensional visualization revealed that autophagy is dramatically induced at the specific stages throughout the tapetal cells just before their PCD process (Fig. 1). This monitoring system offers a powerful tool to analyze the regulation of autophagy in rice tapetum during anther development, and contribute to the research to increase the grain quality and yield of rice.

This work was supported in part by the NIG-Joint program (84A2018).

Glossary
Autophagosome: A spherical structure with double layer membranes. It is the key structure in macroautophagy, the intracellular degradation system for cytoplasmic contents.

Figure: Visualization of the dynamics of autophagosomes/autophagy-related structures in rice anthers.
(A) A confocal fluorescence image of cross-section of rice anthers indicates GFP (green) and autofluorescence (magenta) of chlorophyll, respectively. Arrowheads indicate punctate signals of GFP-ATG8 (autophagosomes/autophagy-related structures). (B) Three-dimensional reconstruction of the tapetum undergoing autophagy.