Poster: Photomorphogenesis

Abs # 503: Phytochrome in cotyledons regulates the expression of genes in the hypocotyl through auxin-dependent and independent pathways

Presenter:	Tanaka, Shin-Ichiro , shin@physiol.bot.kyoto-u.ac.jp
Authors	Tanaka, Shin-Ichiro  (A)   Satoshi, Nakamura  (A)   Nobuyoshi, Mochizuki  (A)   Akira, Nagatani  (A)
Affiliations:	(A): Kyoto University, Biological Science

To elucidate the mechanism of plant responses to the shade, we identified three promoter/enhancer trap lines (M812, J53, J59) that exhibited reporter expression in the hypocotyl in response to the end-of-day far-red light treatment. Interestingly, we found auxin-responsive genes in the vicinities of the reporter insertion sites in two of these lines (M812, J53). We examined the effects of auxin on the reporter expression in these lines together with the previously identified N35 line. The results indicated that the reporter expression was induced by exogenous auxin in two of the four lines (N35, J53). Furthermore, the auxin transport inhibitor inhibited the responses of these lines to the end-of-day far-red light treatment, suggesting the involvement of auxin in the responses of plants to the shade. By contrast, neither auxin nor the transport inhibitor affected the response in the other two lines (M812, J59). Interestingly, one of these lines responded to ABA. Hence, ABA might be involved in the response as well. We then examined the photoreceptive sites for the responses. The results indicated that the cotyledon but not the hypocotyl was the major photoreceptive sites both in the auxin-responsive and ABA-responsive lines. Hence, some signals appeared to be transmitted from the cotyledon to the hypocotyl. We are also screening the mutants that show different patterns of GUS expression patterns from N35 line and hope to show some datas related to the isolated lines.