The tip cell of the protonema of the moss Ceratodon purpureus (Hedw.) Brid. is negatively gravitropic when grown in the dark on supplemented agar. Gravitropism, plastid distribution, and plastid movement were studied in living cells using time-lapse video microscopy and infrared light. A wrong-way (downward) curvature preceded upward curvature and was detected as early as 2 minutes after reorientation. Upward curvature began 30-45 minutes after reorientation to the horizontal. Cell division temporarily reversed upward curvature, but did not inhibit wrong-way curvature. Since significant amyloplast sedimentation always occurred before the start of upward curvature, it is possible that these amyloplasts function as statoliths for upward curvature. However, no significant amyloplast sedimentation occurred before wrong-way curvature. Thus, this early phase of gravitropism cannot require plastid sedimentation for gravity sensing. Most plastids moved within and between zones, and plastid zonation was highly dynamic. Plastids moved toward the apex and toward the base of the cell at rates much slower than cytoplasmic streaming. Despite the dynamic nature of plastid movement and zonation, during upward curvature the distance between sedimented plastids and the apex stayed constant. Time-lapse analysis has revealed intriguing events not readily seen previously using destructive sampling.
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页码
v.1348-1358(12)
其它主题
Gravite; Anatomia de la planta; Anatomie vegetale; Lumiere; Obscurite
语言
英语
注释
references. AVAILABILITY: US (DNAL 450 AM36).
类型
Journal Article; Journal Part
来源
American-journal-of-botany (USA). (Dec 1992). v. 79(12) p. 1348-1358.
团体作者
Ohio State University, Columbus, OH
2012-11-15
AGRIS AP