title: In vivo monitoring of intracellular chloroplast movements in intact leaves of C4 plants using two-photon microscopy.
abstract: Dynamic changes in the spatial distribution of chloroplasts are essential for optimizing photosynthetic capacity under changing light conditions. Light-induced movement of chloroplasts has been widely investigated, but most studies were conducted on isolated tissues or protoplasts. In this study, a two-photon microscopy (TPM) system was adapted to monitor the intracellular 3-dimensional (3D) movements of chloroplasts in intact leaves of plants during dark to light transitions. The TPM imaging was based on autofluorescence of chlorophyll generated by a femto-second Ti:Sapphire laser. All chloroplasts did not exhibit the same motion in response to irradiation variation. In the sub-epidermal mesophyll cells, chloroplasts generally moved away from the surface following blue light treatment, however many chloroplasts did not show any movement. Such spatial heterogeneity in chloroplast motility underlines the importance of monitoring intracellular orientation and movement of individual chloroplasts across intact leaves. Our investigation shows that the 3D imaging of chloroplasts using TPM can help to understand the changes in local photosynthetic capacity in intact leaves under changing environmental conditions.
authors.affiliation: Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja Dong, Nam-Gu, Pohang, Gyeongbuk, 790-784, Korea; Center for Biofluid and Biomimic Research, Pohang University of Science and Technology (POSTECH), San 31, Hyoja Dong, Nam-Gu, Pohang, Gyeongbuk, 790-784, Korea.
authors.forename: Jeongeun
authors.initials: J
authors.lastname: Ryu
authors.forename: Hyoseok
authors.initials: H
authors.lastname: Nam
authors.forename: Hae Koo
authors.initials: HK
authors.lastname: Kim
authors.forename: Yongjoon
authors.initials: Y
authors.lastname: Joo
authors.forename: Sang Joon
authors.initials: SJ
authors.lastname: Lee
authors.forename: Ki Hean
authors.initials: KH
authors.lastname: Kim
mesh_terms: D002736:Chloroplasts / Q000502:physiology / Q000648:ultrastructure*; D021621:Imaging, Three-Dimensional / Q000379:methods; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D018515:Plant Leaves / Q000502:physiology / Q000648:ultrastructure*; D045868:Sorghum / Q000502:physiology / Q000648:ultrastructure*; D003313:Zea mays / Q000502:physiology / Q000648:ultrastructure*
keywords: chloroplast; intact plants; intracellular movement; photosynthetic capacity; two-photon microscopy