Physical interaction between peroxisomes and chloroplasts elucidated by in situ laser analysis

Kazusato Oikawa, Shigeru Matsunaga, Shoji Mano, Maki Kondo, Kenji Yamada, Makoto Hayashi, Takatoshi Kagawa, Akeo Kadota, Wataru Sakamoto, Shoichi Higashi, Masakatsu Watanabe, Toshiaki Mitsui, Akinori Shigemasa, Takanori Iino, Yoichiroh Hosokawa & Mikio Nishimura

Life on earth relies upon photosynthesis, which consumes carbon dioxide and generates oxygen and carbohydrates. Photosynthesis is sustained by a dynamic environment within the plant cell involving numerous organelles with cytoplasmic streaming. Physiological studies of chloroplasts, mitochondria and peroxisomes show that these organelles actively communicate during photorespiration, a process by which by-products produced by photosynthesis are salvaged. Nevertheless, the mechanisms enabling efficient exchange of metabolites have not been clearly defined. We found that peroxisomes along chloroplasts changed shape from spherical to elliptical and their interaction area increased during photorespiration. We applied a recent femtosecond laser technology to analyse adhesion between the organelles inside palisade mesophyll cells of Arabidopsis leaves and succeeded in estimating their physical interactions under different environmental conditions. This is the first application of this estimation method within living cells. Our findings suggest that photosynthetic-dependent interactions play a critical role in ensuring efficient metabolite flow during photorespiration.

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