G. Kalsi et Me. Etzler, Localization of a nod factor-binding protein in legume roots and factors influencing its distribution and expression, PLANT PHYSL, 124(3), 2000, pp. 1039-1048
The roots of the legume Dolichos biflorus contain a lectin/nucleotide phosp
hohydrolase (Db-LNP) that binds to the Nod factor signals produced by rhizo
bia that nodulate this plant. In this study we show that Db-LNP is differen
tially distributed along the surface of the root axis in a pattern that cor
relates with the zone of nodulation of the root. Db-LNP is present on the s
urface of young and emerging root hairs and redistributes to the tips of th
e root hairs in response to treatment of the roots with a rhizobial symbion
t or with a carbohydrate ligand. This redistribution does not occur in resp
onse to a non-symbiotic rhizobial strain or a root pathogen. Db-LNP is also
present in the root pericycle where its level decreases upon initiation of
nodule formation. Maximum levels of Db-LNP are found in 2-d-old roots, and
the expression of this root protein is increased when the plants are grown
in the absence of NO3- and NH4+. These results support the possibility tha
t Db-LNP is involved ii! the initiation of the Rhizobium legume symbiosis.