A new source of root-knot nematode resistance from Arachis stenosperma incorporated into allotetraploid peanut (Arachis hypogaea)

Authors: BALLEN-TABORDA, CAROLINA - University Of Georgia; CHU, YE - University Of Georgia; OZIAS-AKINS, PEGGY - University Of Georgia; Timper, Patricia - Patty; Holbrook, Carl - Corley; JACKSON, SCOTT - University Of Georgia; BERTIOLI, DAVID - University Of Georgia; LEAL-BERTIOLI, SORAYA - University Of Georgia

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/2019
Publication Date: 12/2/2019
Citation: Ballen-Taborda, C., Chu, Y., Ozias-Akins, P., Timper, P., Holbrook Jr, C.C., Jackson, S., Bertioli, D., Leal-Bertioli, S. 2019. A new source of root-knot nematode resistance from Arachis stenosperma incorporated into allotetraploid peanut (Arachis hypogaea). Scientific Reports. 9:17702. https://doi.org/10.1038/s41598-019-54183-1.
DOI: https://doi.org/10.1038/s41598-019-54183-1

Interpretive Summary: The peanut root-knot nematode (RKN) is a very destructive pathogen, to which most peanut cultivars are highly susceptible. It results in yield losses and reduces pod and grain quality. However, resistance is present in the wild relative Arachis stenosperma. In previous research, markers for locations containing major resistance genes were identified on three chromosomes in the wild relative. Here, we studied the inheritance of nematode resistance within the genetic background of cultivated peanut. A second-generation population was developed from a hybrid cross between the peanut cultivar, Runner IAC-886 and A. stenosperma. Genetic analysis was used to identify the major markers for nematode resistance within the hybrid peanut background, allowing us to verify the presence of two genetic regions derived from A. stenosperma, each contributing to a percentage reduction in nematode multiplication. In conclusion, we found that the strong resistance to RKN from genes derived from the wild species A. stenosperma are transferrable and expressed in cultivated peanut. We also discovered that the genetic marker for the high level of RKN resistance is in a region rich in known plant defense genes which may be involved in reducing nematode multiplication. These wild-derived genes can be used in breeding programs for transferring new sources of nematode resistance into elite peanut cultivars.

Technical Abstract: Root-knot nematode (RKN, Meloidogyne arenaria) is a very destructive pathogen, to which most peanut (Arachis hypogaea) cultivars are highly susceptible. It results in yield losses and reduces pod and grain quality. However, resistance is present in the wild diploid relative A. stenosperma. Using a diploid mapping population developed from a cross of A. stenosperma x A. duranensis, major loci conferring resistance were previously mapped to chromosomes A02, A04 and A09. Here, we studied the inheritance of nematode resistance within the genetic background of tetraploid cultivated peanut. An F2 population was developed from a cross between the A. hypogaea cultivar, Runner IAC-886 with an induced allotetraploid that incorporated A. stenosperma, (Arachis batizocoi x A. stenosperma)4x. This population was genotyped using the ‘Axiom_Arachis v01’ 58K high-density SNP array and phenotyped for three measurements of nematode resistance (eggs per gram of root, reproduction factor and galling index). Analysis of quantitative trait loci was used to identify the major genetic determinants of nematode resistance within the tetraploid genetic background. A framework map comprised of 1499 polymorphic SNP markers in combination with phenotypic data, allowed us to verify a previously described major-effect diploid QTL on chromosome A02, and a secondary QTL on A09 of A. stenosperma, each contributing to a percentage reduction in nematode multiplication up to 98.2%. Selected F2-derived F3 (F2:3) lines were used to validate the A. stenosperma-derived alleles that confer resistance and linked markers for selection. Finally, manual inspection of SNP markers revealed tetrasomic genetic inheritance in the wild-cultivated population studied. The strong resistance to RKN conferred by alleles derived from the diploid species A. stenosperma are transferrable and expressed in cultivated, tetraploid peanut. We found that near the location of a large-effect QTL at the bottom of chromosome A02, resides a TIR-NBS-LRR rich region that may be involved in plant defenses against RKN. These wild-derived alleles can be used in breeding programs for introgression of a new source of nematode resistance into elite peanut genetic backgrounds.