Genetic mapping of Mt-NS1 . A, Growth phenotypes of A20 (Nod+, ns1/ns1), F83005.5 (Nod-, NS1/NS1), and a subpopulation of F2 plants three weeks post inoculation with S. meliloti Rm41. Nodulated plants are green and healthy, whereas the non-nodulated plants showed nitrogen starvation symptoms with yellowish leaves under the nitrogen-free condition. B, Fine mapping of Mt-NS1. The Mt-NS1 locus was delimited to a genomic region between markers SNP103 and SNP127. Numbers indicate the number of recombination breakpoints separating the marker from Mt-NS1 based on genotyping ~3,900 F2 plants. C, Annotation of the 50-kb genomic DNA of Jemalong A17 (Nod + Fix-, ns1/ns1) that covers the candidate gene region identifies 7 putative genes (Medtr8g28070-Metr8g28115). D, Identification of an insertion/deletion polymorphism between the two copies of the receptor-like kinases (Metr8g28110 and Metr8g28115) among the genomes of Jemalong A17, A20, and F83005.5.