Jenkins G I, Courtice G R, Cove D J
Department of Genetics, University of Leeds, U.K.
Plant Cell Environ. 1986;9(8):637-44. doi: 10.1111/j.1365-3040.1986.tb01621.x.
The gravitropic responses of dark-grown caulonemata and gametophores of wild-type and mutant strains of the moss Physcomitrella patens have been investigated. In the wild-type both caulonemata and gametophores show negative orthogravitropism. No gravitropic response is observed when plants are rotated slowly on a clinostat and the inductive effect of gravity can be replaced by centrifugal force. The gravitropic response of caulonemanta is biphasic, consisting of an initial phase producing a bend of about 20 degrees within 12 h of 90 degrees reorientation and a subsequent slower phase leading to completion of the 90 degrees curvature. No obvious sedimentation of statoliths accompanies this response. Several mutants have been isolated that are either partially or completely impaired in caulonemal gravitropism and one mutant shows a positive gravitropic response. Complementation analysis using somatic hybrids obtained following protoplast fusion indicates that at least three genes can mutate to give an altered gravitropic phenotype. None of these mutants is altered in gametophore gravitropism, suggesting that the gravitropic response of caulonemal filaments may require at least some gene products that are not required for the response of the multicellular gametophores. One class of mutant with impaired caulonemal gravitropism shows a pleiotropic alteration in leaf shape.
对苔藓小立碗藓野生型和突变株黑暗生长的茎丝体和配子体的向重力性反应进行了研究。在野生型中，茎丝体和配子体均表现出负向直向重力性。当植株在回转器上缓慢旋转时，未观察到向重力性反应，重力的诱导作用可被离心力替代。茎丝体的向重力性反应是双相的，包括在重新定向90度后的12小时内产生约20度弯曲的初始阶段，以及随后导致90度曲率完成的较慢阶段。此反应过程中没有明显的平衡石沉降。已分离出几个在茎丝体向重力性方面部分或完全受损的突变体，其中一个突变体表现出正向重力性反应。利用原生质体融合后获得的体细胞杂种进行互补分析表明，至少有三个基因发生突变会导致向重力性表型改变。这些突变体在配子体向重力性方面均未改变，这表明茎丝体的向重力性反应可能需要至少一些多细胞配子体反应不需要的基因产物。一类茎丝体向重力性受损的突变体在叶片形状上表现出多效性改变。
