Root-knot nematodes, Meloidogyne spp., are obligate, Chit wood and M. incognita Chit wood. They cause serious sedentary endoparasites of many plant species. Their damage to tomato and pepper crops (Lamberti, 1979), especially in potential host range encompasses more than 3000 plant tropical, sub-tropical and warm climates. In Egypt, the most important and widely spread in different soil types and locations are the root knot nematodes which are in some cases they consider as limiting factors of tomato and pepper production (Houssny and Oteifa, 1956).
While most hot pepper Capsicum annuum L. cultivars are resistant to the root-knot nematode species Meloidogyne incognita, they are usually susceptible to the Southern root-knot nematode M. javanica (Taylor and Sasser, 1978; Peixoto, 1995). Even though varietal resistance is considered one of the most efficient methods for nematode control (Ferraz and Mendes, 1992), very little emphasis has been placed on breeding peppers for nematode resistance.
The N gene and the Me genes have been reported to control resistance to root-knot nematodes in pepper, Capsicum annuum (Castagnone-Sereno et al. 2001; Hare, 1956; Hendy et al. 1985; Feiy and Dukes, 1996). Hendy et al. (1985) observed five genes, designated Me1 to Me5 that control resistance to various Meloidogyne spp. Two of these genes, Me1 and Me3, confer broad spectrum resistance to M. incognita, M. arenaria, and M.javanica (Hendy et al. 1985). Likewise, the N gene confers high resistance to M. incognita, M. arenaria races 1 and 2, and M. javanica (Thies and Fery, 2000). Although each gene system has been individually well characterized, resistance controlled by the two genetic systems has not been compared in a single study; e.g. there is no information about the relationship of the N. and Me gene systems to each other and whether the N and Me genes are allelic. (Thies and Fery, 2000).
The use of molecular markers has been proposed as an alternative procedure (Toby et al., 1999). Molecular markers based on polymorphisms of the DNA are specially useful for this enterprise, because they are not affected by the environment (Tatineni et al., 1996).
The Random Amplified Polymorphic DNA (RAPD-PCR) and Inter Sequence Repeat Polymerase Chain Reaction (ISSR-PCR) technique has been widely used to quantify the genetic variation due to its simplicity and power to detect differences, even among closely related individuals, in species of Brassica (Jain et al., 1994), Pisum (Hoey et al., 1996), Wheat (Liu et al., 1999) and Pepper (Refaat and Hoda, 2007 and Geleta et al. 2004 and Kumar et al., 2001).
The objective of this study was to inheritance and screening F1, F2 and BC1 plants’ resistance to M. incognita race 2 derived from a cross The cultivars P1, P4, and P5 and P3 (Resistant) with the local cultivar susceptible P7 by ISSR-PCR to Identification of molecular markers linked to the N gene will facilitate marker- assisted selection and the isolation of the N resistance gene and will develop host plant genetic resistance through breeding and DNA manipulation which includes: (I) development of molecular tagging and identify and track resistance genes, and (II)development of improved to identify, evaluate and confirm resistance in large host plant populations.
|
