Department of Genetics, Research School of Biological Sciences, The Australian National University, Canberra, A.C.T. 2601, Australia.
Appl Environ Microbiol. 1986 Feb;51(2):328-32. doi: 10.1128/aem.51.2.328-332.1986.
Ten fluorescein isothiocyanate-labeled lectins were tested on the roots of the tropical legume Macroptilium atropurpureum Urb. Four of these (concanavalin A, peanut agglutinin, Ricinis communis agglutinin I [RCA-I], wheat germ agglutinin) were found to bind to the exterior of root cap cells, the root cap slime, and the channels between epidermal cells in the root elongation zone. One of these lectins, RCA-I, bound to the root hair tips in the mature and emerging hair zones and also to sites at which root hairs were only just emerging. There was no RCA-I binding to immature trichoblasts. Preincubation of these lectins with their hapten sugars eliminated all types of root cell binding. By using a microinoculation technique, preincubation of the root surface with RCA-I lectin was found to inhibit infection and nodulation by Rhizobium spp. Preincubation of the root surface with the RCA-I hapten beta-d-galactose or a mixture of RCA-I lectin and its hapten failed to inhibit nodulation. Application of RCA-I lectin to the root surface caused no apparent detrimental effects to the root hair cells and did not prevent the growth of root hairs. The lectin did not prevent Rhizobium sp. motility or viability even after 24 h of incubation. It was concluded that the RCA-I lectin-specific sugar beta-d-galactose may be involved in the recognition or early infection stages, or both, in the Rhizobium sp. infection of M. atropurpureum.
十种荧光素异硫氰酸酯标记的凝集素被用于测试热带豆科植物大波斯菊的根部。其中四种（刀豆球蛋白 A、花生凝集素、蓖麻凝集素 I [RCA-I]、麦胚凝集素）被发现与根冠细胞外表面、根冠黏液以及根伸长区表皮细胞之间的通道结合。这些凝集素中的一种，RCA-I，与成熟和新出现的根毛区的根毛尖端以及根毛刚刚出现的部位结合。RCA-I 与未成熟的毛原细胞没有结合。这些凝集素与它们的半抗原糖预先孵育消除了所有类型的根细胞结合。通过使用微量接种技术，发现 RCA-I 凝集素预先孵育根表面可抑制根瘤菌属的侵染和结瘤。预先孵育 RCA-I 半抗原β-D-半乳糖或 RCA-I 凝集素与其半抗原的混合物未能抑制结瘤。将 RCA-I 凝集素应用于根表面对根毛细胞没有明显的有害影响，也不会阻止根毛的生长。即使在孵育 24 小时后，该凝集素也不会阻止根瘤菌属的运动或存活。结论是，RCA-I 凝集素特异性糖β-D-半乳糖可能参与了根瘤菌属对大波斯菊的识别或早期侵染阶段，或者两者都参与了。
