A cloned cellulase gene from Erwinia carotovora subsp. carotovora is expressed in Rhizobium fredii but does not influence nodulation of cowpea

Abstract

Symbiotic rhizobia enter roots of their hosts via infection threads in root-hairs and invade the cortex, where nodules are initiated. We have transferred a cloned cellulase (Cel) gene from Erwinia carotovora subsp, carotouora into rhizobia and examined both the production of the enzyme and its impact on nodulation. Acquisition of a Cel + plasmid allowed cultured cells of Rhizobium fredii, R. meliloti, and R. tropici to produce extracellular enzymes that degrade carboxymethylcellulose. The Cel + plasmid was retained by R. fredii during nodulation of cowpea, and analysis of a gene fusion confirmed that the Cel promoter was active in planta. Cellulase levels in nodules nevertheless were low, and infection and nodulation were unaffected by the presence of the Cel + plasmid.

Cloning and expression of a β-1,4-endoglucanase gene fromCellulomonassp. CelB7 inEscherichia coli; purification and characterization of the recombinant enzyme

“…The most important are endoglucanases (endo-1,4-p-~-glucanase, 1,4-P-D-glucan glucohydrolase; EC 3.2.1.4) and exoglucanases (cellulose 1,4-P_cellobiosidase; EC 3.2.1.91). Bacterial and fungal cellulase genes have been cloned and expressed in yeast [2] and bacteria [3,4]. E. coli is commonly used as a host for the expression of endoglucanases because it does not produce enzymes involved in plant cell wall degradation [5,6].…”

Purification and Characterization of an α-Glucosidase from Rhizobium sp. ( Robinia pseudoacacia L.) Strain USDA 4280

“…In addition, a ␤-galactosidase and a ␤-glucosidase have been purified from the periplasmic space of Rhizobium trifolii (1), and an endoglucanase gene from Azorhizobium caulinodans has been cloned (14). However, the cellulase gene of Erwinia carotovora expressed in Rhizobium fredii has no effect on nodulation of cowpea (20).…”

Análisis molecular y funcional de la celulasa celc2 en la simbiosis rhizobia-leguminosas

“…Tampoco la expresión de una celulasa de la familia 5 de las glicosil hidrolasas de Erwinia carotovora subsp. carotovora en Sinorhizobium fredii supuso ningún defecto en el proceso de infección y nodulación en caupí (Krishnan y Pueppkea, 1994), aunque se observó que los niveles de expresión en el nódulo eran bajos.…”