RT Journal Article SR Electronic T1 Leaf-to-whole plant spread bioassay for pepper and Ralstonia solanacearum interaction determines inheritance of resistance to bacterial wilt for further breeding JF bioRxiv FD Cold Spring Harbor Laboratory SP 2021.01.27.428365 DO 10.1101/2021.01.27.428365 A1 Ji-Su Kwon A1 Jae-Young Nam A1 Seon-In Yeom A1 Won-Hee Kang YR 2021 UL http://biorxiv.org/content/early/2021/01/27/2021.01.27.428365.abstract AB Bacterial wilt (BW) disease by Ralstonia solanacearum is a serious disease and causes severe yield losses in chili peppers worldwide. Resistant cultivar breeding is the most effective in controlling BW. Thus, a simple and reliable evaluation method is required to assess disease severity and to investigate the inheritance of resistance for further breeding programs. Here, we developed a reliable leaf-to-whole plant spread bioassay for evaluating BW disease and then, using this, determined the inheritance of resistance to R. solanacearum in peppers. Capsicum annuum ‘MC4’ displayed a completely resistant response with fewer disease symptoms, a low level of bacterial cell growth, and significant up-regulations of defense genes in infected leaves compared to those in susceptible ‘Subicho’. We also observed the spreading of wilt symptoms from the leaves to the whole susceptible plant, which denotes the normal BW wilt symptoms, similar to the drenching method. Through this, we optimized the evaluation method of the resistance to BW. Additionally, we performed genetic analysis for resistance inheritance. The parents, F1 and 90 F2 progenies, were evaluated, and the two major complementary genes involved in the BW resistance trait were confirmed. These could provide an accurate evaluation to improve resistant pepper breeding efficiency against BW.Competing Interest StatementThe authors have declared no competing interest.