Inheritance of Partial Resistance to Isolate VdLs17 of Verticillium dahliae Within Lactuca spp

Lettuce (Lactuca sativa L.) production is greatly threatened by Verticillium wilt, which is caused by three pathogenic races (races 1, 2, and 3) of the soilborne fungus Verticillium dahliae. Race 1 is predominant, and resistant varieties that provide full protection against it are commercially available. However, heavily relying on race 1-resistant cultivars could shift the population towards resistance-breaking isolates and impact the durability of plant resistance. This study determined the inheritance of partial resistance to isolate VdLs17 of V. dahliae within Lactuca spp. using 258 F_2:3 progeny generated from a cross between two partially resistant accessions, 11G99 (L. serriola) and PI 171674 (L. sativa). Eight experiments were performed under greenhouse and growth room conditions across 3 years using a randomized complete block design, and segregation analysis was conducted to determine the inheritance pattern. The results indicate that partial resistance to isolate VdLs17 of V. dahliae is conditioned by a two-major-gene genetic model with additive-dominance-epistatic effects. Transgressive segregants were infrequent but observed in both directions, indicating that favorable and adverse alleles are dispersed in both parents. Combining favorable alleles of these two partially resistant parents appears to be challenging because of epistatic effects and a significant role of environment in disease severity. The probability of capturing favorable additive genes could be maximized by generating and evaluating a large population and making selections at late generations. This study provides valuable insights into the inheritance pattern of partial resistance to isolate VdLs17 of V. dahliae that will be helpful in designing efficient breeding strategies in lettuce.[Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.