セミナー情報

Higher plants have advanced light sensing and signaling systems to control their growth and development. In Arabidopsis, multiple photoreceptors including five phytochromes (phyA-E), two cryptochromes (cry1 2) two phototropins (phot1 2) and UVR8 control de-etiolation and/or phototropism (Kami et al., 2010, Rizzini et al., 2011). The phototropins are required for phototropism. phot1 is more sensitive than phot2 to blue light and is thus the primary photoreceptor in low blue light (Christie 2007). Genetic studies have identified a limited number of phototropin signaling components, including NPH3, RPT2, PKS1 and PKS2 that interact with the phototropins and specifically work in phototropin signaling (Motchoulski et al., 1999, Sakai et al., 2001, Lariguet et al., 2006, de Carbonnel et al., 2010). Interestingly, phyA and crys are also required for normal phototropism in low blue light (Lariguet and Fankhauser 2004, Whippo and Hangarter 2004, Tsuchida-Mayama et al., 2010). phyA was proposed to promote phototropism by inhibiting gravitropism (Lariguet and Fankhauser 2004). In addition, many publications suggest a direct role of phyA in promoting phototropism (Han et al., 2008, Rösler et al., 2007). Moreover, phyA in etiolated seedlings have a function for promotion of phototropism by red light pretreatment before giving blue light (Janoudi 1997, Parks 1996). In this seminar, I would like to talk about 1) phyA nuclear signaling promotes phototropism, 2) Gene expression analysis suggested that phyA signaling promotes gene expression of phototropism regulators (e.g. PKS1 and RPT2) which are strongly upregulated by nuclear phyA signaling in blue light, 3) PKS proteins may integrate the phy- & phot- dependent signaling in hypocotyl growth orientation, 4) PKS may function for auxin accumulation or signaling in elongation zone of etiolated seedlings. Christie (2007), Annu Rev Plant Biol. 58:21-45: de Carbonnel et al., (2010), Plant Physiol 152(3):1391-405: Janoudi e al., (1997), Plant Physiol. 113(3):975-9: Han et al., (2008), Plant Cell. 20(10):2835-47. Kami et al., (2010), Curr Top Dev Biol. 91:29-66: Lariguet et al., (2006), Proc Natl Acad Sci U S A. 103(26):10134-9: Lariguet and Fankhauser (2004), Plant J. 40(5):826-34: Motchoulski and Liscum (1999), Science. 286(5441):961-4: Parks et al., (1996), Plant Physiol. 110(1):155-62: Rizzini et al., (2011), Science. 332(6025):103-6.: Rösler et al., (2007), Proc Natl Acad Sci U S A. 104(25):10737-42: Sakai et al., (2000) Plant Cell. 12(2):225-36: Tsuchida-Mayama et al., (2010), Plant J. 62(4):653-62: Whippo and Hangarter (2004). Plant Cell Environ. 27 1223–1228.