Inheritance of Resistance to Bacterial Wilt in Chinese Dragon Groundnuts

Abstract

Bacterial wilt (BW) caused by Ralstonia solanacearum E.F.Smith is an important constraint to groundnut (Arachis hypogaea L.) production in China, Indonesia and Vietnam. Genetic improvement for host plant resistance is the most effective control for this disease. In the 1970s, several groundnut germplasm lines with high resistance to bacterial wilt, including Xiekangqing and Taishan Sanlirou, were identified and used extensively in breeding programs. However, almost all the BW resistant groundnut cultivars developed in China during the past two decades were related to a few resistant donors belonging to subsp. fastigiata (Liao et al.,1994), and the narrow genetic background of resistance donors has obviously impeded breeding BW-resistant cultivars with higher yield potential. Since 1985, further screening for bacterial wilt resistance in groundnut was conducted, and more resistant materials were found in all four botanical types of the cultivated groundnut (Duan et al. 1993). Fifty-one highly-resistant landraces were identified in dragon type groundnuts, mostly related to subsp.hypogaea var. hirsuta (Jiang et al. 1994); additional resistant dragon accessions were subsequently found (Duan et al. 1996). The frequency of resistant landraces was obviously much higher in the dragon type than in the other three types because more than seventy were resistant in of the 250 dragon landraces surveyed. Moreover, all the resistant dragon lines were collected from south China where bacterial wilt is generally serious (Duan et al. 1993; Jiang et al. 1994; Liao et al. 1994).