Gravity perception requires statoliths settled on specific plasma membrane areas in characean rhizoids and protonemata

Markus Braun*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)

Abstract

The noninvasive infrared laser micromanipulation technique (optical tweezers, optical trapping) and centrifugation were used to study susception and perception, the early events in the gravitropic pathway of tip-growing characean rhizoids and protonemata. Reorientation of the growth direction in both cell types was only initiated when at least 2-3 statoliths settled on specific areas of the plasma membrane. This statolith-sensitive plasma membrane area is confined to the statolith region (10-35 μm behind the tip) in positively gravitropic rhizoids, whereas in negatively gravitropic protonemata, this area is limited to the apical plasma membrane (0-10 μm). Statolith sedimentation towards the sensitive plasma membrane areas is mediated by the concerted action of actin and gravity. The process of sedimentation, the pure physical movement, of statoliths is not sufficient to initiate graviresponses in both cell types. It is concluded that specific statolith-sensitive plasma membrane areas play a crucial role in the signal transduction pathway of gravitropism. These areas may represent the primary sites for gravity perception and may transform the information derived from the gravity-induced statolith sedimentation into physiological signals which trigger the molecular mechanisms of the opposite graviresponses in characean rhizoids and protonemata.

Original languageEnglish
Pages (from-to)150-159
Number of pages10
JournalProtoplasma
Volume219
Issue number3-4
DOIs
Publication statusPublished - 2002
Externally publishedYes

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