Inheritance of Ineffective Nodulation in Cowpea
- I. J. Pemberton,
- G. R. Smith and
- J. C. Miller
Nodulation is a critical step in the development of the legume-Rhizobium symbosis. A cowpea [Vigna unguiculata (L.) Walp.] plant of the varietal mix ‘Iron & Clay’ with small, white, ineffective nodules was observed during a greenhouse experiment and designated IC-l. Experiments were conducted to determine the genetic control of ineffective nodulation in cowpea. The IC-1 S1 plants were ineffectively nodulated and no nitrogenase activity was detected by acetylene-reduction assay. No segregation for symbiotic effectiveness was noted in the S2 and S3 generations of IC-1. Crosses were made between IC-1 S1 and normal, effectively nodulating Iron & Clay cowpea, resulting in four F2 families that segregated into effective and ineffective nodulation classes. Based on x2 analysis, ineffective nodulation in cowpea is determined by a simply inherited recessive gene, designated cpi. The interaction of cpi and eight cowpea Bradyrhizobium strains was investigated, and no strain effects were noted. Non-strain-specific ineffective nodulation of cowpea is conditioned by a single recessive gene pair (cpi cpi).
Copyright © 1990.