Harnessing wild peanut genetic resources for field resistance to tomato spotted wilt and late leaf spot diseases.

Abstract

Tomato spotted wilt virus (TSWV) and late leaf spot (LLS) are among the major constraints to peanut production. Cultivated peanut has narrow genetic bases and lacks strong sources of resistance. Wild species, on the other hand, harbor diverse and strong resistances to multiple pathogens. In this study, we evaluated advanced breeding lines carrying introgressions from multiple wild Arachis species (A. stenosperma, A. batizocoi, A. valida, and A. cardenasii) across three contrasting field environments and experimental designs in Georgia, USA using complementary incidence- and severity-based phenotyping. Genotype effects were highly significant for both diseases. Several wild-derived lines -particularly those from A. stenosperma ancestry- showed strong and stable TSWV resistance across environments. Interestingly, some lines lacking detectable wild segments also showed high resistance to TSWV, suggesting cryptic or undetected introgressions. LLS resistance was primarily associated with the characteristic A. cardenasii segments on A02 and A03, and lines stacking these introgressions consistently outperformed both cultivated parents and Georgia-06G, the most popular cultivar in the USA. Correlations between TSWV and LLS responses were weak, confirming genetic independence and emphasizing the need to screen both traits. A small subset of lines combined resistance to both diseases, and many also retained resistance loci to root-knot nematode (RKN), expanding their value as multi-trait donors. These findings demonstrate the power of wild introgression breeding for enhancing disease resistance and provide a foundation for deploying stacked alleles through marker-assisted and multi-environment selection.