| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2000: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1999: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
Many photoresponses are regulated by dichroic phytochrome molecules in ferns and other lower plants including mosses. In the present work, I aimed to elucidate the dichroic phytochrome molecule and to analyze its regulatory processes of phototropism and intracellular chloroplast photorelocation. Results obtained are as follows.
1)Dichroic phytochrome-mediate chloroplast relocation movement in the moss, Physcomitrella patens : As in the case of fern protonemata, chloroplast photorelocation movement in Physcomitrella protonemal cells was shown, for the first time, to be regulated by dichroic phytochrome as well as by dichroic blue light receptor. Further analyses on the motile system using cytoskeletal inhibitors revealed that phytochrome responses utilize only microtubules as tracks while blue light responses use both microtubule and actin microfilament systems. The differential regulation of motile systems by photoreceptors has never been reported before and well contrasts with case of fern, where both photoreceptors regulate microfilament system but not microtubule system.
2)Gene disruption of dichroic phytochrome in the fern Adiantum capillus-veneris : By introducing a disruption construct of PHY3, a candidate of dichroic phytochrome gene to a protonemal cell, we obtained a strain which lacks both phototropism and chloroplast photorelocation regulated by phytochrome. The strain still retained the blue light-induced responses. Detailed analyses are still on the way.
3)Analyses on the Physcomitrella cells over-expressing fern PHY3 gene : Fern PHY3 gene was introduced and over-driven by 35S promoter in the moss cells. However, no effect on the red light-induced phototropism or chloroplast relocation movement was observed.
4)Isolation of Adiantum mutant altered in the orientation of dichroic phytochrome : Screening of mutants which are defective in the intracellular orientation of dichroic phytochrome are performed, but so far, no strains are obtained.
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