Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: February 26, 2001
Publication Date: August 20, 2001
Citation: Thies, J.A., Fery, R.L. 2001. Root-knot nematodes: Need for host plant resistance in cowpea [Abstract]. Hortscience. 36(5):850. Technical Abstract: Root-knot nematodes (Meloidogyne spp.) are severe pests of cowpea (Vigna unguiculata) in the southern U.S. and worldwide. Four species of root-knot nematodes (Meloidogyne incognita, M. javanica, M. arenaria, and M. hapla) are known to parasitize cowpea. Of these, M. incognita and M. javanica cause the greatest yield losses, although M. arenaria and M. hapla may reduce cowpea yields in local areas. Host plant resistance is the most efficient and economical method for managing root-knot nematodes in cowpea. Although several root-knot resistant cowpea cultivars are available, most of the cultivars that are commonly grown in the U.S. are susceptible. Resistance in the majority of resistant U.S. cowpea cultivars is governed by a single dominant gene designated Rk. Another single dominant gene, Rk2 (allelic to Rk) confers greater resistance than gene Rk to M. incognita and M. javanica, and is also effective against resistance-breaking isolates of these two Meloidogyne species. Gene Rki, a single recessive gene also allelic to Rk, confers an intermediate-type resistance in cultivars such as 'Pink-eye Purple Hull', compared to the highly susceptible 'New Era'. Recently, gene Rk3, a single recessive gene independent of Rk, was discovered that confers a high level of broad spectrum resistance to M. incognita and M. javanica, when it is present in combination with gene Rk. These four resistance genes will be useful in the development of new cowpea cultivars with high, broad-spectrum resistance that should be effective against both virulent and avirulent isolates of root-knot nematodes.