苜蓿假盘菌与苜蓿叶片亲和性互作的超微结构特征

从细胞角度揭示苜蓿假盘菌与苜蓿叶片亲和性互作机制。以两者亲和性互作系统为研究材料,利用透射电子显微镜技术研究了苜蓿假盘菌与苜蓿叶片亲和性互作的超微结构特征。结果表明,病菌侵入寄主组织后,菌丝直接穿透寄主细胞壁进入寄主细胞形成胞内菌丝,以胞内生长并向相邻细胞扩展。病菌菌丝穿透寄主细胞壁时,菌丝中的液泡给予了较大的压力帮助其穿透。进入寄主细胞内的病菌菌丝,被内陷的寄主原生质膜包裹,菌丝与质膜始终是隔离的,寄主原生质膜和细胞壁之间沉积电子致密度深的物质。病菌菌丝不断地在寄主原生质膜区域扩展,伴随菌丝体在寄主细胞内的不断扩大,周围的原生质膜也相应扩大其面积,但始终将寄主原生质与菌丝体隔开,而脱离质膜的菌丝形成菌丝鞘包裹。随侵染程度的增加,未被穿透的寄主原生质膜区域逐步被降解。病菌侵染叶绿体等细胞器时,首先是菌丝鞘与叶绿体等细胞器膜相连,然后降解其基粒片层结构,被降解的细胞器组织沿菌丝和胞壁周围沉积。侵染后期,菌丝胞内和胞外扩展,但处在细胞降解物中的菌丝显示较厚的细胞壁,寄主细胞内充满了大量的黑色物质和结晶状的颗粒物。

Ultrastructural characteristics of compatible Pseudopeziza medicaginis interaction with alfalfa leaf

Ultrastructural characteristics of the compatible interaction between Pseudopeziza medicaginis and alfalfa was studied using transmission electron microscopy (TEM). When P. medicaginis invaded host tissue, the hyphae directly penetrated the host cell wall and formed intracellular hyphae with growth in the cell and expansion into the adjacent cell. Hyphal penetration of host cell walls was assisted by greater vacuole pressure. Hyphae within host cells were wrapped by invagination of the host plasma membrane and mycelium and plasma membrane were always isolated and there was deposition of electron dense, dark material between host plasma membrane and cell wall. Pathogen hyphae continued to expand in the host plasma membrane region with a corresponding expansion in the host cell’s, plasma membranes which separated the host protoplast and from the mycelium. The hyphae separated from the plasma membrane to form a hyphal sheath. With an increase in the amount of infection, the region of host plasma membrane that was not penetrated was gradually degraded as P. medicaginis infected chloroplasts and other organelles. First, the mycelial sheath connected to the chloroplast and other organelle membranes, then the degradation of grana lamellae structure and degraded organelle tissues were deposited along the mycelium and around the cell wall. At a later stage of infection, the mycelium expanded both intra and extracellularly, but the hyphae in degraded cells had thick cell walls and the host cells filled with a lot of black material and crystalline particulate matter.