The gravitropism of caulonemata of Pottia intermedia is described and compared with that of other mosses. Spore germination produces primary protonemata including caulonemata which give rise to buds that form the leafy moss plant, the gametophore. Primary caulonemata are negatively gravitropic but their growth and the number of filaments are limited in the dark. Axenic culture of gametophores results in the production of secondary caulonemata that usually arise near the leaf base. Secondary protonemata that form in the light are agravitropic. Secondary caulonemata that form when gametophores are placed in the dark for several days show strong negative gravitropism and grow well in the dark. When upright caulonemata are reorientated to the horizontal or are inverted, upward bending can be detected after 1 h and caulonemata reach the vertical within 1-2 d. Clear amyloplast sedimentation occurs 10-15 minutes after horizontal placement and before the start of upward curvature. This sedimentation takes place in a sub-apical zone. Amyloplast sedimentation also takes place along the length of upright and inverted Pottia protonemata. These results support the hypothesis that amyloplast sedimentation functions in gravitropic sensing since sedimentation occurs before gravitropism in Pottia and since the location and presence of a unique sedimentation zone is conserved in all four mosses known to gravitropic protonomata.

中文翻译：

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mossPollia inlermedia 花茎的向地性

描述了 Pottia intermedia 的 caulonemata 的向地性，并与其他苔藓进行了比较。孢子萌发产生主要的原虫体，包括产生芽，形成多叶苔藓植物配子体。初级茎突呈负向重力性，但它们的生长和细丝数量在黑暗中受到限制。配子体的无菌培养导致产生通常出现在叶基部附近的次生茎秆。在光中形成的次生原虫是向地的。配子体在黑暗中放置数天时形成的次生茎突表现出强烈的负向重力性，并且在黑暗中生长良好。当直立的茎秆重新定向到水平方向或倒置时，1 h后可检测到向上弯曲，1-2 d内茎秆到达垂直方向。在水平放置后 10-15 分钟和开始向上弯曲之前，会出现清晰的淀粉体沉淀。这种沉积发生在亚顶区。淀粉体沉积也沿直立和倒置的 Pottia protonemata 的长度发生。这些结果支持了以下假设，即淀粉体沉降在向重力感应中起作用，因为在 Pottia 中沉降发生在向地性之前，并且因为在所有四种已知向地性原形纲的苔藓中，独特的沉降带的位置和存在都是保守的。淀粉体沉积也沿直立和倒置的 Pottia protonemata 的长度发生。这些结果支持这样的假设，即淀粉体沉降在向重力感应中起作用，因为沉降发生在 Pottia 的向地性之前，并且因为在所有四种已知向地性原形纲的苔藓中，独特的沉降带的位置和存在都是保守的。淀粉体沉积也沿直立和倒置的 Pottia protonemata 的长度发生。这些结果支持了以下假设，即淀粉体沉降在向重力感应中起作用，因为在 Pottia 中沉降发生在向地性之前，并且因为在所有四种已知向地性原形纲的苔藓中，独特的沉降带的位置和存在都是保守的。