Rhizoid differentiation of Spirogyra is regulated by substratum

Abstract

Some species of Spirogyra can anchor to substratum with rod- or rosette-shaped rhizoid (hapteron). The rhizoid differentiation can be induced by cutting algal filaments in a laboratory. Requirement of contact stimulation for rhizoid differentiation has been reported (Nagata in Plant Cell Physiol 14:531-541, 1973a). However, the control mechanism of rhizoid morphology has not been elucidated. When cut filaments were incubated on the glass surface, start of tip growth, secretion of lectin-binding material and callose synthesis were observed. In the absence of contact to the glass surface, none of above phenomena was induced. Systematic analysis showed that rosette-shaped rhizoid was formed only on the hydrophobic substratum. On the hydrophobic substratum, both Bandeiraea (Griffonia) simplicifolia lectin and jacalin strongly stained the rhizoids. On the hydrophilic substratum, however, only Bandeiraea (Griffonia) simplicifolia lectin strongly stained the rhizoids.

Studies on conjugation of Spirogyra using monoclonal culture

“…Thus, lectin-binding materials secreted during conjugation seem different to some extent among species. We previously reported that BSL-I and jacalin showed contrasting stain patterns in rhizoid: jacalin clearly stained the outline of rhizoid, while staining with BSL-I was diffused (Inoue et al 1999, Ikegaya et al 2008b). It was suggested that the BSL-I-binding material was responsible for adhesion of filaments to the substratum.…”

“…It was suggested that the BSL-I-binding material was responsible for adhesion of filaments to the substratum. On the other hand, the jacalin-binding material was speculated to be involved in recognition of substratum (Ikegaya et al 2008b). In the present study, therefore, we focused our attention on BSL-I and jacalin (Fig.…”

“…We have been engaged in rhizoid differentiation of Spirogyra (Inoue et al 1999, 2002; Yamada et al 2003; Yoshida et al 2003, 2006, 2008; Yoshida and Shimmen 2007, 2009; Ikegaya et al 2004, 2008a, b). Randhawa (1959) discussed similarity between rhizoid formation and conjugation process; both result from a contact stimulus.…”

“…Randhawa (1959) discussed similarity between rhizoid formation and conjugation process; both result from a contact stimulus. Contact of the cell end to the substratum is essential for differentiation of rhizoid (Nagata 1973; Ikegaya et al 2008b). At the beginning of rhizoid formation, a papilla is formed and elongates via tip growth (Nagata 1973).…”

Rhizoid formation inValonia(Siphonocladales, Chlorophyceae)

“…According to these reports, tenaculae are for attachment of branches to each other to provide close packing and reinforcement. On the other hand, Ikegaya et al (2008) reported that absence of contact stimulation failed to promote rhizoids in Spirogyra; however, distance of the cell from the substratum probably exceeded the range needed for rhizoid induction.…”