应力诱导的菊花原生质体定向性伸长响应

MECHANICAL STRESS INDUCES ORIENTATED ELONGATION IN THE PROTOPLASTS ISOLATED FROM CHRYSANTHEMUM

从单细胞水平探索了应力条件对植物细胞伸长这一生长发育过程中的基本和重要现象的影响。从菊花叶片中分离原生质体并将其包埋于琼脂糖凝胶块中,通过自主研发的微应力加载装置对该细胞-凝胶混合物施加机械挤压,加载后的凝胶块培养并切片后进行细胞形态分析,采用基于有限元方法的ABAQUS软件计算细胞周围的应力场,发现受到应力刺激的原生质体在培养过程中倾向于以垂直于凝胶块中主应力张量的方向伸长,应力强度与这种细胞响应遵照某种非线性的剂量依赖关系,且该响应会受到外源性含RGD序列的多肽的抑制。说明植物单细胞具有响应外部力学信号的能力;植物细胞质膜上可能存在与动物细胞系统中类似的RGD特异结合受体,它在应力条件下的细胞伸长响应中可能参与了力学信号的介导。

This paper aim to investigate the influence of mechanical stress on plant cell elongation, being involved in the fundamental and important processes in the growth and development of plant. In the study, spherical protoplasts prepared from chrysanthemum （Dendranthema morifolium） were embedded into agarose block. Constant uniaxial pressure released by a fabricated loading apparatus was imposed on the opposite sides of the block. After that, the loaded protoplasts-gel block was cultured in liquid medium and then chipped to slices for morphological analysis. An ABAQUS software based finite element method was used to simulate the mechanical loading procedure and map the distribution of principal stress in the block. The results showed that the protoplast-regenerated cells tended to elongate with a preferential axis oriented perpendicularly to the compressive stress direction, according to a certain dose-dependent relationship between the intensity of compressive force and the stress induced responses, which could not be observed in the present of RGD-contained peptides. These findings suggest that an individual plant cell separated from multicellular environments does retain the ability to respond to directional mechanical signals, and this response requires the mediation via interaction between plasma membrane-bound receptors within the ECM that contain RGD motif.