PDF(Pubmed)
Abstract：
Plant cell differentiation is based on rearrangements of the tubulin cytoskeleton; this is also true for symbiotic nodules. Nevertheless, although for indeterminate nodules (with a long-lasting meristem) the organization of microtubules during nodule development has been studied for various species, for determinate ones (with limited meristem activity) such studies are rare. Here, we investigated bacteroid morphology and dynamics of the tubulin cytoskeleton in determinate nodules of four legume species: Glycine max, Glycine soja, Phaseolus vulgaris, and Lotus japonicus. The most pronounced differentiation of bacteroids was observed in G. soja nodules. In meristematic cells in incipient nodules of all analyzed species, the organization of both cortical and endoplasmic microtubules was similar to that described for meristematic cells of indeterminate nodules. In young infected cells in developing nodules of all four species, cortical microtubules formed irregular patterns (microtubules were criss-crossed) and endoplasmic ones were associated with infection threads and infection droplets. Surprisingly, in uninfected cells the patterns of cortical microtubules differed in nodules of G. max and G. soja on the one hand, and P. vulgaris and L. japonicus on the other. The first two species exhibited irregular patterns, while the remaining two exhibited regular ones (microtubules were oriented transversely to the longitudinal axis of cell) that are typical for uninfected cells of indeterminate nodules. In contrast to indeterminate nodules, in mature determinate nodules of all four studied species, cortical microtubules formed a regular pattern in infected cells. Thus, our analysis revealed common patterns of tubulin cytoskeleton in the determinate nodules of four legume species, and species-specific differences were associated with the organization of cortical microtubules in uninfected cells. When compared with indeterminate nodules, the most pronounced differences were associated with the organization of cortical microtubules in nitrogen-fixing infected cells. The revealed differences indicated a possible transition during evolution of infected cells from anisotropic growth in determinate nodules to isodiametric growth in indeterminate nodules. It can be assumed that this transition provided an evolutionary advantage to those legume species with indeterminate nodules, enabling them to host symbiosomes in their infected cells more efficiently.
摘要：
植物细胞分化基于微管蛋白细胞骨架的重排；共生结节也是如此。然而，尽管对于不确定的结节（具有持久的分生组织），已针对各种物种研究了结节发育过程中微管的组织，对于确定的（具有有限的分生组织活性），此类研究很少见。这里,我们研究了四种豆科植物的确定结节中微管蛋白细胞骨架的类细菌形态和动力学：甘氨酸max，大豆大豆,菜豆,和莲花。在大豆根瘤中观察到最明显的类细菌分化。在所有分析物种的初期结节中的分生组织细胞中，皮质和内质微管的组织与不确定结节的分生组织细胞的组织相似。在所有四个物种正在发育的结节中的年轻感染细胞中，皮质微管形成不规则的模式（微管交叉），内质层微管与感染线和感染滴有关。令人惊讶的是,在未感染的细胞中，一方面，G.max和G.soja结节中皮质微管的模式不同，另一个是普通疟原虫和日本血吸虫。前两个物种表现出不规则的图案，而其余两个表现出规则的（微管横向于细胞的纵轴），这对于不确定结节的未感染细胞是典型的。与不确定的结节相反，在所有四个研究物种的成熟确定结节中，皮质微管在受感染的细胞中形成规则的模式。因此，我们的分析揭示了四种豆科植物的确定结节中微管蛋白细胞骨架的共同模式，物种特异性差异与未感染细胞中皮质微管的组织有关。与不确定结节相比，最明显的差异与固氮感染细胞中皮质微管的组织有关.揭示的差异表明，在受感染细胞的进化过程中，可能会从确定结节中的各向异性生长转变为不确定结节中的等轴生长。可以假设，这种转变为那些结节不确定的豆科植物提供了进化优势，使它们能够更有效地在被感染的细胞中宿主共生体。
