Hibberd J M, Jeschke W D
Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
J Exp Bot. 2001 Oct;52(363):2043-9. doi: 10.1093/jexbot/52.363.2043.
Parasitic plants form intimate contacts with host tissue in order to gain access to host solutes. There are a variety of cell types within the host which parasitic plants could access to extract solutes. Depending on the degree to which the parasite has embraced the parasitic lifestyle, the extent of solute flux and the pathways used to transfer solutes from host to parasite will vary. To date, a variety of experimental approaches argue for diversity in the mechanisms and the routes by which parasites accumulate host solutes. Contact between host and parasite ranges from direct lumen-to-lumen links between host and parasite xylem and continuity between the sieve elements of host and parasite, to the involvement of transfer cells between host and parasite. Progress has been slow since Solms-Laubach distinguished types of parasitic plants that fed from host phloem or xylem in 1867, but advances in clearly delineating the pathways that link host and parasite should now be possible using fluorescent proteins expressed and restricted to particular cell types of the host. This will initially necessitate using Arabidopsis, but should allow the types of connection, i.e. symplasmic or apoplasmic, to be determined and then the identification of parasite transporters responsible for solute flux.
寄生植物与宿主组织形成紧密接触，以便获取宿主溶质。宿主中有多种细胞类型可供寄生植物获取溶质。根据寄生植物接受寄生生活方式的程度，溶质通量的大小以及用于将溶质从宿主转移到寄生植物的途径会有所不同。迄今为止，各种实验方法都表明，寄生虫积累宿主溶质的机制和途径存在多样性。宿主与寄生虫之间的接触范围从宿主与寄生虫木质部之间直接的管腔到管腔连接以及宿主与寄生虫筛管分子之间的连续性，到宿主与寄生虫之间转移细胞的参与。自1867年索尔姆斯 - 劳巴赫区分了从宿主韧皮部或木质部获取养分的寄生植物类型以来，进展一直缓慢，但现在利用在宿主特定细胞类型中表达并受限的荧光蛋白，应该能够清楚地描绘连接宿主和寄生虫的途径。这最初需要使用拟南芥，但应该能够确定连接类型，即共质体或质外体连接，然后鉴定负责溶质通量的寄生虫转运蛋白。
