Soybean nodulin genes: Analysis of cDNA clones reveals several major tissue-specific sequences in nitrogen-fixing root nodules

Abstract

Plant gene products that could play a role in the process of symbiotic nitrogen fixation in leguminous plants were detected by screening a cDNA library prepared from soybean nodule poly(A)+ RNA. About 13% of the 5,700 clones screened contained sequences detectable with a root cDNA probe while about 2,100 clones (37% of the library) contained sequences that were detectable only with nodule cDNA. Five unique sequence species, accounting for more than half of the 2,100 nodule-specific clones, were identified by cross-hybridization experiments. The most abundant species, represented by 860 clones, encodes the wellcharacterized protein, leghemoglobin (Lb). The other four species, designated NodA, NodB, NodC, and NodD, are represented by 350, 55, 61, and 6 clones, respectively. Each of these four species was found to be encoded by the plant nuclear genome at low copy number. The transcripts corresponding to the nodule-specific clones represented 12-15% (Lb), 6% (NodA), and 0.5-1.1%

Appearance of Purine-Catabolizing Enzymes in Fix+ and Fix− Root Nodules on Soybean and Effect of Oxygen on the Expression of the Enzymes in Callus Tissue

“…Class II includes enzymes responsible for the assimilation of nitrogen (9). Among the other enzymes involved in purine catabolism, the specific activities of 5'-nucleotidase, purine nucleosidase and xanthine dehydrogenase have been shown to be significantly higher in root nodules than in uninfected roots (7, some activity of these enzymes within this organelle.…”

Identification of key genes involved in root development of tomato using expressed sequence tag analysis

“…Evans et al (1988) isolated root-specific cDNA clones from pea and concluded that rootspecific mRNA species are present at a very low level. Fuller et al (1983) have cloned and characterized a number of nodule-specific genes. Bogusz et al (1988) isolated a haemoglobin gene expressed specifically in roots of nonnodulating plants.…”

Characterization and Gene Expression of Nodulin Npv30 from Common Bean

“…A highly expressed late nodulin gene family of unknown function, the nodulin-A family, has been found in soybean (Fuller et al, 1983;Jacobs et al, 1987). The nodulin-A family comprises at least six members: Ngm-20 (Sandal et al, 1987), Ngm-23 (Mauro et al, 1985), Ngm-26b (Jacobs et al, 1987), Ngm-22/Ngm-27 (Jacobs et al, 1987;Sandal et al, 1987), Ngm-44 (Sengupta-Gopalan et al, 19861, and 15-9-A (Gottlob-McHugh and Johnson, 1991).…”