Development and Genetic Characterization of Peanut Advanced Backcross Lines That Incorporate Root-Knot Nematode Resistance From Arachis stenosperma

Carolina Ballén-Taborda; Ye Chu; Peggy Ozias-Akins; C Corley Holbrook; Patricia Timper; Scott A Jackson; David J Bertioli; Soraya C M Leal-Bertioli

doi:10.3389/fpls.2021.785358

Development and Genetic Characterization of Peanut Advanced Backcross Lines That Incorporate Root-Knot Nematode Resistance From Arachis stenosperma

Front Plant Sci. 2022 Jan 17:12:785358. doi: 10.3389/fpls.2021.785358. eCollection 2021.

Authors

Carolina Ballén-Taborda¹, Ye Chu², Peggy Ozias-Akins^{1

2}, C Corley Holbrook³, Patricia Timper³, Scott A Jackson¹, David J Bertioli^{1

4}, Soraya C M Leal-Bertioli^{1

5}

Affiliations

¹ Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Athens, GA, United States.
² Department of Horticulture, University of Georgia, Tifton, GA, United States.
³ U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Tifton, GA, United States.
⁴ Department of Crop and Soil Science, University of Georgia, Athens, GA, United States.
⁵ Department of Plant Pathology, University of Georgia, Athens, GA, United States.

Abstract

Crop wild species are increasingly important for crop improvement. Peanut (Arachis hypogaea L.) wild relatives comprise a diverse genetic pool that is being used to broaden its narrow genetic base. Peanut is an allotetraploid species extremely susceptible to peanut root-knot nematode (PRKN) Meloidogyne arenaria. Current resistant cultivars rely on a single introgression for PRKN resistance incorporated from the wild relative Arachis cardenasii, which could be overcome as a result of the emergence of virulent nematode populations. Therefore, new sources of resistance may be needed. Near-immunity has been found in the peanut wild relative Arachis stenosperma. The two loci controlling the resistance, present on chromosomes A02 and A09, have been validated in tetraploid lines and have been shown to reduce nematode reproduction by up to 98%. To incorporate these new resistance QTL into cultivated peanut, we used a marker-assisted backcrossing approach, using PRKN A. stenosperma-derived resistant lines as donor parents. Four cycles of backcrossing were completed, and SNP assays linked to the QTL were used for foreground selection. In each backcross generation seed weight, length, and width were measured, and based on a statistical analysis we observed that only one generation of backcrossing was required to recover the elite peanut's seed size. A populating of 271 BC₃F₁ lines was genome-wide genotyped to characterize the introgressions across the genome. Phenotypic information for leaf spot incidence and domestication traits (seed size, fertility, plant architecture, and flower color) were recorded. Correlations between the wild introgressions in different chromosomes and the phenotypic data allowed us to identify candidate regions controlling these domestication traits. Finally, PRKN resistance was validated in BC₃F₃ lines. We observed that the QTL in A02 and/or large introgression in A09 are needed for resistance. This present work represents an important step toward the development of new high-yielding and nematode-resistant peanut cultivars.

Keywords: Arachis; Meloidogyne arenaria; domestication; marker-assisted backcrossing; peanut; root-knot nematode; wild crop relatives.