Gravi- and photostimuli in moss protonema growth movements

Molecular mechanisms of gravity perception and signal transduction in plants

“…In mosses, gravity perception and gravitropic bending are both carried out in the same cell, an apical cell of the chloronema. Amylochloroplasts containing large starch grains in this cell are believed to play the role of statoliths (Demkiv et al 1998;Walker and Sack 1990). In higher plants, the sites of gravity perception and reaction are spatially separated.…”

A role for the cytoskeleton in plant cell gravisensitivity and Ca2+‐signaling in microgravity

“…It is supposed that some differences in the actin cytoskeleton organization between root and stem statocytes may determine the different degree of root and stem gravisensitivity (Fitzelle and Kiss, 2001). The apical cell of moss protonemata displays a certain internal polarity, and amylochloroplasts are believed to play the role of statoliths (Demkiv et al, 1998;Walker and Sack, 1990). In these cells, a degree of reorganization of microtubules under gravistimulation and in altered gravity allowed them to assume their contribution in both graviperception and plastid reorientation in microgravity (Kern et al, 2001).…”

Photomorphogenesis of Mosses

“…In Funaria, germination is most sensitive to light in the red region of the spectrum and the red light effect can be reversed by far-red light (Bauer and Mohr, 1959), thus phytochrome is involved in this regulation. Red-far-red reversibility of germination has since been demonstrated for spores of Ceratodon, Dicranum scoparium (Valanne, 1966) and Physcomitrella (Schild, 1981;Cove et al, 1978Hofmann et al, 1999;Brun et al, 2001;Imaizumi et al, 2002;Koprivova al., 2002;Koprivova et al, 2002;Zank et al, 2002;Li et al, 2002;Meiri et al, Bünning and Etzold, 1958;Nebel, 1968;Jenkins and Cove, 1983b;Hartmann et al, 1983;Demkiv et al, 1998;Esch et al, 1999 Cove et al, 1978;Jenkins et al, 1986;Young and Sack, 1992;Lamparter et al, 1996;Demkiv et al, 1997a;Lamparter et al, 1998b;Kern and Sack, 1999 (Cove and Lamparter, 1998;Imaizumi et al, 2002). Dark growing filaments form only very few side branches.…”

“…In general, the tip cell grows towards the light (positive phototropism, see Figure 2 a), but in particular cases, the tip cell can also grow away from the light (negative phototropism). Whereas in shoots of seed plant seedlings, phototropism is mediated by the blue light photoreceptor phototropin, this effect is regulated by phytochrome in many moss species (Nebel, 1968;Jenkins and Cove, 1983b;Hartmann et al, 1983;Demkiv et al, 1998;Bünning and Etzold, 1958). A similar response termed polarotropism can be induced by polarized light.…”