Summary
Root nodule initiation in Pisum sativum begins with cell divisions in the inner cortex at some distance from the advancing infection thread. After penetrating almost the entire cortex, the branches of the thread infiltrate the meristematic area previously initiated in the inner cortical cells. These cells are soon invaded by bacteria released from the infection thread and subsequently differentiate into non-dividing, bacteriod-containing cells. As the initial meristematic centre in the inner cortex is thus lost to bacteroid formation, new meristematic activity is initiated in neighbouring cortical cells. As development proceeds, more cortical layers contribute to the nodule, with the peripheral layer and apical meristem of the nodule not invaded by bacteria.
Lateral root primordia are initiated in a region separate from that in which nodules are formed, with the lateral primordia being closer to the root apex. This is interpreted to indicate that the physiological basis for nodule initiation is distinct from that for initiation of lateral roots. The role of a single tetraploid cell in nodule initiation is refuted, as is the existence of incipient meristematic foci in the root. It is suggested that the tetraploid cells in nodule meristems arise from pre-existing endoreduplicated cells, or by the induction of endoreduplication in diploid cortical cells by Rhizobium.
Similar content being viewed by others
References
Bond, L.: Origin and developmental morphology of root nodules of Pisum sativum. Bot. Gaz. 109, 411–434 (1948)
Bucknall, R. A., Sutcliffe, J. F.: The nucleic acids and cellular differentiation in the root apex of Pisum sativum. J. exp. Bot. 16, 423–432 (1965)
Johansen, D. A.: Plant microtechnique. New York-London: McGraw-Hill 1940
Kodama, A.: Cytological and morphological studies on the plant tumors. II. Root nodules of some Leguminosae. J. Sci. Hiroshima Univ., Ser. B, Div. 2, 13, 223–260 (1970)
Libbenga, K. R.: Nodulatie bij Leguminosae. Doct. dissert., Univ., Leiden, The Netherlands (1970)
Libbenga, K. R.: Torrey, J. G.: Hormone-induced endoreduplication prior to mitosis in cultured pea root cortex cells. Amer. J. Bot. 60, 293–299 (1973)
Maácz, G. J., Vágás, E.: A new method for staining of cellulose and lignified cell walls. Mikroskopie 16, 40–43 (1961)
Nutman, P. S.: Physiological studies on nodule formation. I. The relation between nodulation and lateral root formation in red clover. Ann. Bot. 12, 81–96 (1948)
Nutman, P. S.: Origin and developmental physiology of root nodules. In: Encyclopedia of plant physiology, vol. XV, pt. 1, p. 1355–1379, Ruhland, W., ed. Berlin-Heidelberg-New York: Springer 1965
Oinuma, T.: Cytological and morphological studies on root nodules of garden pea, Pisum sativum L. Seitbusu 3, 155–161 (1948) (Cited after Torrey and Barrios, 1969.)
Philips, D. A.: A cotyledonary inhibitor of root nodulation in Pisum sativum. Physiol. Plantarum (Cph.) 25, 482–487 (1971)
Raggio, M., Raggio, N.: Relación entre cotiledones y nodulación y factores que la afectan. Phyton (Vicente López, Argent.) 7, 103–119 (1956)
Steedman, H. F.: Section cutting in microscopy. Oxford: Blackwell Scient. Publns. (1960)
Torrey, J. G., Barrios, S.: cytological studies on rhizobial nodule initiation in Pisum. Caryologia 22, 47–62 (1969)
Wipf, L.: Chromosome numbers in root nodules and root tips of certain Leguminosae. Bot. Gaz. 101, 51–67 (1939)
Wipf, L., Cooper, D. C.: Chromosome numbers in nodules and roots of red clover, common vetch and garden pea. Proc. nat. Acad. Sci. (Wash.) 24, 87–91 (1938)
Wipf, L., Cooper, D. C.: Somatic doubling of chromosomes and nodular infection in certain Leguminosae. Amer. J. Bot. 27, 821–824 (1940)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Libbenga, K.R., Harkes, P.A.A. Initial proliferation of cortical cells in the formation of root nodules in Pisum sativum L.. Planta 114, 17–28 (1973). https://doi.org/10.1007/BF00390281
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00390281