Interaction between Orobanche crenata and its host legumes:: unsuccessful haustorial penetration and necrosis of the developing parasite
Interaction between Orobanche crenata and its host legumes:: unsuccessful haustorial penetration and necrosis of the developing parasite
复制标题
DOI：
10.1093/aob/mci105
复制
发表时间：
2005-05-01
期刊：
影响因子：
4.2
通讯作者：
Joel, DM
中科院分区：
文献类型：
--
作者：
Pérez-De-Luque, A;Rubiales, D;Joel, DM
背景和目的在世界上许多地区，矮腰草是制约作物生产的主要因素，因为它们降低了产量并改变了根/梢异速生长。虽然人们对弓形虫的组织学和对易感寄主的影响了解甚多，但对寄主对这些寄生虫的抗性基础了解甚少。在这项工作中，为了确定哪些类型的抗性反应参与了不成功的渗透，研究了一些豆科植物对绿腹蛇的抗性的组织学方面。方法收集不同基因型抗性豆科植物对绿腹草的抗性反应。采用不同的方法对样品进行固定、切片和染色。切片用透射光显微镜和外延荧光观察。内胚层和中柱鞘寄主细胞的木质素化似乎阻止了寄生虫在感染早期侵入根维管柱。但在其他情况下，已形成的结核会坏死并死亡。与之前的一些研究相反，研究发现，后一种情况下，感染部位的变暗并不对应于宿主组织的死亡，而是对应于宿主-寄生虫界面和许多被感染宿主组织中填充外质体的物质的分泌。分泌物会阻塞邻近的宿主血管。这可能会干扰宿主和寄生虫之间的营养流动，并可能导致发育中的寄生虫坏死和死亡。结论豆科植物寄主体内细胞的死亡不能解释成豆科植物寄主体内细胞的死亡。这似乎与穿透部位宿主内胚层和中柱鞘细胞的木质化有关。分泌物在感染部位的积累可能导致木质部闭塞（另一种防御机制）的激活，这可能导致已建立的结核进一步坏死。
Background and Aims Orobanche species represent major constraints to crop production in many parts of the world as they reduce yield and alter root/shoot allometry. Although much is known about the histology and effect of Orobanche spp. on susceptible hosts, less is known about the basis of host resistance to these parasites. In this work, histological aspects related to the resistance of some legumes to Orobanche crenata have been investigated in order to determine which types of resistance responses are involved in the unsuccessful penetration of O. crenata.Methods Samples of resistance reactions against O. crenata on different genotypes of resistant legumes were collected. The samples were fixed, sectioned and stained using different procedures. Sections were observed using a transmission light microscope and by epi-fluorescence.Key Results Lignification of endodermal and pericycle host cells seems to prevent parasite intrusion into the root vascular cylinder at early infection stages. But in other cases, established tubercles became necrotic and died. Contrary to some previous studies, it was found that darkening at the infection site in these latter cases does not correspond to death of host tissues, but to the secretion of substances that fill the apoplast in the host-parasite interface and in much of the infected host tissues. The secretions block neighbouring host vessels. This may interfere with the nutrient flux between host and parasite, and may lead to necrosis and death of the developing parasite.Conclusions The unsuccessful penetration of O. crenata seedlings into legume roots cannot be attributed to cell death in the host. It seems to be associated with lignification of host endodermis and pericycle cells at the penetration site. The accumulation of secretions at the infection site, may lead to the activation of xylem occlusion, another defence mechanism, which may cause further necrosis of established tubercles.