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Autonomous helical movement of plant organs, originally termed circumnutation by Charles Darwin in the 19th century, is ubiquitously observed in land plants. In Cuscuta campestris, a stem parasitic plant whose stems coil around the host stem during parasitization, this movement plays a critical role in searching for a host. Although patterns of circumnutation have been extensively investigated in several species under different environmental conditions, such as variable light and temperature, and after chemical exposure, the mechanisms underpining this movement remain largely unknown. This is partly due to the lack of suitable methods for acquiring high-resolution spatio-temporal images of plant organs during circumnutation. To address this issue, we designed a time-lapse image acquisition system with two video cameras: one positioned to capture images from above and the other to capture images from the side of the plant. Using this camera system, images of circumnutating C. campestris shoots were captured under different light conditions, and the effects of light quality on the winding angle and rotation rate of circumnutation were quantified. The results indicate the utility of this imaging system in evaluating the effects of light quality on circumnutation, and highlight the need for improvements in data resolution for 3D image analysis., Departmental Bulletin Paper, 原著, 2020年度 神奈川大学総合理学研究所共同研究助成論文

第30回宇宙環境利用シンポジウム (2016年1月19日-20日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)), 相模原市, 神奈川県, Space Utilization Research (January 19-20, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 著者人数: 12名, 資料番号: SA6000048044, レポート番号: G-40

An agravitropic mutant of morning glory (Pharbitis nil.), weeping, has defect in shoot gravitropism. The previous results showed that weeping also showed defect in proper endodermis development and in shoot circumnutation, and such defect in circumnutation was also observed in similar endodermis-less Arabidopsis mutant, scarecrow (scr). In search of the mutated gene of weeping, cDNAs for SCR homolog from morning glory (PnSCR) were cloned from both wild type and weeping, respectively, and analyzed. An amino acid insertion was found in PnSCR from weeping. To investigate whether this insertion inactivates the PnSCR functions, complementation test was performed by introducing wild and weeping type PnSCR to the different Arabidopsis scr mutants respectively. As a result, endodermis-less and shoot agravitropic phenotypes were rescued by wild type introducing PnSCR, whereas introduction of weeping type PnSCR did not rescue them. Moreover, shoot circumnutation was also restored in scr mutant to which wild type PnSCR was transformed, but transformed weeping type PnSCR did not restore shoot circumnutation. These results strongly suggest that defects in gravitropism, proper endodermis development, and circumnutation observed in weeping are attributable to the loss of function of PnSCR. Possibility for usage of weeping morning glory as a new model plant in space biology is discussed., 資料番号: AA0048095069

第26回宇宙利用シンポジウム(2010年1月25日-26日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-sixth Space Utilization Symposium (January 25-26, 2010: ISAS/JAXA Sagamihara, Japan), Studies of our working group are aimed at understanding the graviperception mechanism and its interactions with mechanisms of other gravity-influenced phenomena of plant growth and development. Our collaborative works will bring about hypotheses on the molecular mechanisms underlying plant responses to gravity, which will be further verified by spaceflight experiments. This approach will also lead to the establishment of technology useful for controlling plant growth and development in space. We have continued our studies to reveal mechanisms underlying graviperception and its signal transduction in plants by using gravitropic mutants, and found various genes and molecules responsible for the mutations. Also, we have studied the gravity-influenced growth and development of plants; namely, gravimorphogenesis of cucumber seedlings, shoot circumnutation, and hydrotropism in seedling roots. The results obtained suggested molecular cascades for graviresponse and molecular networks for the interactions among the gravity-influenced phenomena. Based on these accomplishments, we are attempting to establish models and hypotheses to be verified by spaceflight experiments. Some of the subjects being dealt in this project are to be flown in this year. Currently, we are preparing to propose another spaceflight experiment on circumnutation and its relationship to graviresponse in plants., 共催: 日本学術会議, 著者人数: 17人, joint hosting: The Science Council of Japan, 資料番号: AA0064730068

第27回宇宙利用シンポジウム (2011年1月24日-25日, 宇宙航空研究開発機構宇宙科学研究所相模原キャンパス), 相模原市, 神奈川県, The Twenty-seventh Space Utilization Symposium (January 24-25, 2011. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, Circumnutation is a helical growth movement of tips of shoots and roots observed among various plant species. Circumnutation is considered to help plant organs find suitable environmental cues. Using agravitropic mutants, we have revealed that graviresponse is necessary for circumnutation in dicotyledonous plants such as Arabidopsis and morning glory. However, its mechanism in monocotyledonous plants is currently unknown. To investigate the relationship between graviresponsiveness and circumnutation in monocots, we used agravitropic mutant of rice, lazy1, and compared its circumnutation with that of wild-type. Coleoptile of wild-type rice exhibited obvious circumnutation when it was vigorously growing. On the other hand, the coleoptile of the lazy1 did not show obvious circumnutation despite the entire growth of coleoptile was similar to wild-type. These results suggest that circumnutation is closely related to gravitropic response. Furthermore, we found that treatment of an inhibitor of auxin efflux drastically reduced circumnutation in wild-type coleoptiles. Thus, it is suggested that circumnutation requires gravity-regulated auxin efflux in rice coleoptiles., 資料番号: AA0065129057