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ARS Home » Midwest Area » Urbana, Illinois » Soybean/maize Germplasm, Pathology, and Genetics Research » Research » Publications at this Location » Publication #80388
Title: APPARENT SOURCE OF THE RJ5 ALLELE IN SOYBEAN CULTIVARS

Author
item THARP, JR, J - U ILLINOIS, URBANA
item THOMAS, D - U ILLINOIS, URBANA
item NICKELL, CECIL - U ILLINOIS, URBANA
item Harper, James

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Nodulation is a process which involves a beneficial association of a specific bacteria with soybean plant roots and results in providing nitrogen, termed biological dinitrogen fixation, for use by the plant. Understanding genetic control of nodulation in soybean is essential to breeding programs which are attempting to enhance biological dinitrogen fixation. This study was conducted to verify the source of a specific gene which controls presence or absence of nodulation. The ancestor line was identified which carries the gene responsible for expression of nodulation in soybean. This will facilitate selection of breeding materials to evaluate improvement of biological dinitrogen fixation by soybean, and will be beneficial to molecular biologists and physiologists who are evaluating limitations in biological dinitrogen fixation.

Technical Abstract: Two recessive genes, rj5 and rj6, are responsible for controlling non-nodulation in NN5 (a non-nodulating mutant isolated from N-nitroso-N-methylurea mutagenized Williams seed). Previous studies have shown that Harosoy 63 carries Rj5 and Rj6. The objective of this study was to determine the source of Rj5 in Harosoy 63 and if other lines carry the Rj5 gene. Crosses between NN5 and twenty-six nodulating cultivars were made to evaluate genetic control. F2 seeds were inoculated with Bradyrhizobium japonicum at planting and seedlings were evaluated for nodulation at 21 days after emergence. The observed segregation ratio of fifteen normal nodulating:one non-nodulating indicated that Rj5 was present, and three normal nodulating:one non-nodulating indicated that rj5 was present. Thirteen lines were identified which carried the dominant Rj5 gene and thirteen lines were identified which carried the recessive rj5 gene. The overall conclusion is that the Rj5 gene in Harosoy 63 traces back to AK (Harrow).