The restriction of nodulation by Rm41 in F83005.5 is controlled by a single dominant gene
For genetic analysis of the nodulation specificity, we used an F2 population derived from the cross between the two M. truncatula genotypes A20 and F83005.5. A20 showed Nod + Fix + phenotype when inoculated with Rm41. From a total of 2,623 inoculated F2 plants, 686 plants nodulated, which fits the 3:1 (non-nodulation to nodulation) ratio (χ2 = 1.86, df = 1, P = 0.17; Figure 3A), suggesting that the restriction of nodulation by Rm41 in F83005.5 is controlled by a single dominant gene. We named this gene as Mt-NS1 (for M. truncatula nodulation specificity 1). Consistent with the cytological studies de- scribed above, the dominant nature of this gene indicates