Poster: Photomorphogenesis

Abs # 505: Functional analysis of Acphot2 using mutants deficient in blue light-induced chloroplast avoidance movement of the fern Adiantum capillus-veneris L.

Presenter:	Kagawa, Takatoshi , kagawa@nibb.ac.jp
Authors	Kagawa, Takatoshi  (A) (B)  Kasahara, Masahiro  (B)   Abe, Tomoko  (C)   Yoshida, Shigeo  (C)   Wada, Masamitsu  (A) (D)
Affiliations:	(A): SORST, Japan Science Technology Corp. (B): National Institute for Basic Biology (C): RIKEN Institute (D): Tokyo Metropolitan University

Mutants deficient in chloroplast avoidance movement under strong blue light were isolated from gametophytes of Adiantum capillus-veneris mutanized by heavy ion beam irradiation. Mutations were found in A. capillus-veneri's PHOT2 as deletions of several nucleotides. The avoidance movements in these mutants were recovered by transient gene expression of AcPHOT2 cDNA, indicating that chloroplast avoidance movement in the fern is mediated by Acphot2. Using this transient assay, functional analysis of Acphot2 was performed using constructs deficient for specific phototropin domains. The results obtained suggest that LOV2 but not LOV1 is essential for avoidance movement and several residues of the C-terminus in the ser/thr kinase domain contribute to this avoidance. The rate of dark reversion of photo-activated LOV2, which was calculated photometrically, was too fast to correspond to the life time of the phot2 signal estimated from physiological responses. The rate of dark reversion of LOV1 + LOV2 domains, however, corresponds to the life time of the signal, suggesting that LOV1 might have some function, although it is not essential for photoperception.