Open AccessNodulation of groundnut by Bradyrhizobium : a simple infection process by crack entry
Author(s) -
Boogerd Fred C,
Rossum Diman
Publication year - 1997
Publication title -
fems microbiology reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.91
H-Index - 212
eISSN - 1574-6976
pISSN - 0168-6445
DOI - 10.1111/j.1574-6976.1997.tb00342.x
Subject(s) - rhizobia , biology , arachis hypogaea , root hair , bradyrhizobium , intracellular , penetration (warfare) , root nodule , arachis , botany , microbiology and biotechnology , nodule (geology) , symbiosis , bacteria , biochemistry , genetics , paleontology , operations research , gene , engineering
Infection of legumes by rhizobia may occur by immediate intercellular penetration of root cells (crack entry) as an alternative mode to the more elaborate infection through infection threads. The intercellular spreading mode of infection is exemplified through a comprehensive description of root infection by Bradyrhizobium and nodule organogenesis in Arachis hypogaea (groundnut). The role of axillary root hairs and the processes of plant penetration and intercellular spreading, of internalization and intracellular multiplication, and of bacteroid differentiation are described. Then flavonoids and phytoalexins, Nod factors, lectins, and surface poly(oligo)saccharides pass in review. The roles of these various (macro)molecules in the chemical communication between the two symbionts are discussed. Attention is given to special features of groundnut nodules; the presence and functions of oleosomes and other bodies, the presence and functions of nodule lectins, and the evidence for the export of amides from the nodules are discussed. Finally, a speculative model for the groundnut infection process is presented.