Kern V D, Mendgen K, Hock B
Lehrstuhl fur Botanik, Technische Universitat Munchen at Freising-Weihenstephan, Germany.
Planta. 1997 Sep;203(Suppl 1):S23-32. doi: 10.1007/pl00008111.
Gravitropic bending of fruiting bodies of Flammulina velutipes (Curtis) Karst. is based on the differential growth of the transition zone between stem and cap. Reorientation becomes visible as early as 2 h after displacing the fruiting body from the vertical to the horizontal position. It is preceded by a preferential accumulation of microvesicles within the hyphae on the lower side of the transition zone and related to an increase in the vacuolar compartment required for hyphal extension. A model made of a bundle of interconnected balloons is used to demonstrate that a differential volume increase at one flank is sufficient to bend the entire structure in the opposite direction. Gravitropic raising of intact stems or segments derived from the transition zone requires positional information which can be accomplished by three major, coordinated events: (i) gravisensing by the individual hyphae within the transition zone, (ii) unidirectional signalling by means of a soluble growth factor creating a vertical concentration gradient, and (iii) translation of the concentration signal into elongation growth.
金针菇子实体的向地性弯曲基于菌柄和菌盖之间过渡区的差异生长。早在将子实体从垂直位置移至水平位置后2小时，重新定向就可见。在此之前，过渡区下侧的菌丝内微泡优先积累，这与菌丝延伸所需的液泡区室增加有关。用一束相互连接的气球制成的模型表明，一侧的差异体积增加足以使整个结构向相反方向弯曲。完整菌柄或来自过渡区的片段的向地性升高需要位置信息，这可通过三个主要的协调事件来实现：(i) 过渡区内单个菌丝的重力感应，(ii) 通过可溶性生长因子进行单向信号传导以形成垂直浓度梯度，以及(iii) 将浓度信号转化为伸长生长。
