Poster: Photomorphogenesis

Abs # 504: Light environment inside stems and roots of seed plants

Presenter:	Sun, Qiang , qiangsun@postman.riken.go.jp
Authors	Sun, Qiang  (A)   Sato-Nara, Kumi  (A)   Yoda, Kiyotsugu  (A) (B)  Suzuki, Hitoshi  (A) (B)
Affiliations:	(A): Photodynamics Research Center, RIKEN (The Institute of Physical and Chemical Research), Japan (B): Faculty of Science and Engineering, Ishinomaki-Senshu University, Japan

Light inside plants, compared to that outside them, exerts more direct influences on light-regulating metabolic activities and therefore has a greater effect on the growth and development of plants. However, previous studies on the internal light environment of plants have been restricted mainly to leaves and seedlings. The present studies deal with the internal light environment of the stems and roots of 50 seed plant species, including gymnosperms and angiosperms, woody and herbaceous species. The results indicate that light could enter the interior of stems and roots and be conducted along the axial direction. Certain elements of vascular tissue (fibers, tracheids and vessels) were found to be efficient axial light conductors, compared with other tissues or cells, despite some slight species differences. The conducted light was greatly attenuated in intensity during axial conduction, but with the spectral range between 720 nm and 930 nm always conducted the most efficiently in both stems and roots. The tissues or cells conducting light did not vary with the seasons, but relative transmission of different wavelengths conducted varied in different seasons: Transmission was relatively higher at 825 nm and 920 nm in the winter-spring period compared with the summer-autumn period. Thus, our investigation revealed light-conducting role of the stem and root of seed plants. The properties of the light conducted also strongly suggest the presence of metabolic activities related to photomorphogenesis within both stem and root.