Functional role of mucilage-root border cells complex in the interface between plant root and soil

在根际土壤中，粘液和根边缘细胞形成一个功能实体，即粘液-边界细胞复合体(MB复合体)。首先，对释放的边界细胞进入实际土壤的寿命进行了分析。许多边缘细胞在根际土壤中存在的时间相对较长，至少在10天以上。寿命将取决于边缘细胞的来源；即当细胞脱落时，根帽层。由于细胞成熟的年轻阶段，来自内层的细胞在土壤中停留的时间更长。MB复合体被根际细菌利用，而根际细菌又承受着土壤食物网的强大放牧压力，特别是原生动物。接下来，我们研究了MB复合体在原生动物对植物生长的积极影响中的作用。首次对27个水稻品种的完全水合MB复合体的重量进行了量化。其次，选取16个不同亚甲基复合体产量的品种进行根缘细胞(RBC)计数。亚甲基复合体的重量因品种而异，一些亚甲基复合体产量较高的品种也产生了较多的红细胞。总的来说，原生动物的存在促进了侧根的生长和碳氮素的吸收。此外，与低地品种相比，旱地品种对变形虫效应的反应更好。MB复合体的产生与阿米巴促进侧根生长的正相关表明MB复合体具有促进与阿米巴共生的功能，这是MB复合体新作用的第一个证据。

In rhizosphere soil, mucilage and root border cells form a functional entity, the mucilage-border cells complex (MB complex). Firstly, the longevity of the released border cells into real soil was analyzed. Many of the border cells present in the rhizosphere soil for relatively longer duration at least more than 10 days. The longevity would depend on the origin of border cells; i.e., root cap layers when the cells are sloughed off. The cells from the inner layer would stay longer in soil due to its younger stage of the cell maturity. The MB complex is utilized by rhizosphere bacteria, which in turn are under strong grazing pressure of the soil food web, in particular protozoa. Next, we investigated the role of MB complex on the protozoan positive effects for plant growth. Weight of fully hydrated MB complex of 27 rice cultivars was firstly quantified. Secondly, 16 cultivars with different levels of MB complex production were selected for root border cells (RBC) enumeration. The weight of MB complex varied among the cultivars and some of the higher MB complex producing cultivars also produced higher number of RBC. Generally speaking, presence of protozoa enhanced lateral root growth and carbon ＆ nitrogen uptake. Further, upland cultivars responded well to amoebal effects as compared with the lowland cultivars. Positive correlation between MB complex production and increased lateral root growth by amoeba revealed that MB complex have a functional role of facilitating a symbiotic relationship with amoeba, which is the first evidence of the new role of MB complex.