Morphological and Genetic Characterization of Non‐Nodulating Peanut Recombinant Inbred Lines

Abstract

Peanut (Arachis hypogaea L.) nodulation is relatively diverged from other legumes. Further understanding of nodulation mechanisms would facilitate improvement of biological N fixation and yield in peanut. The objective of this study was to characterize the non‐nodulating (Nod−) peanut recombinant inbred lines (RILs) in comparison to their nodulating (Nod+) sister RILs morphologically and genetically. Two pairs of Nod− and Nod+ RILs were inoculated with rhizobia for morphological observation. Nodules and root hairs were absent in Nod− lines and present in Nod+ lines. The Nod− lines had a much smaller canopy with yellow leaves and fewer pods than Nod+ lines. Simple‐sequence repeat (SSR) marker genotyping of the two pairs of RILs and their parental lines revealed several chromosome regions differing between Nod− and Nod+ sister lines, which potentially harbor the genes controlling nodulation. Two F2 populations segregating for nodulation were constructed by crossing the two Nod− lines with their Nod+ sister lines. The segregation ratios of Nod−/Nod+ of the two populations followed 7:9 and 7:57, respectively, indicating that multiple genes were involved in controlling peanut nodulation. The results from this study provided important morphological and genetic information related to peanut nodulation, which paved the road for further mapping and cloning of peanut nodulation genes and for eventually developing peanut cultivars with improved N fixation efficiency.