Fine Mapping Of The Root-knot Nematode Resistance Gene Me3 In Pepper (Capsicum Annuum)

The root-knot nematodes is one of the most economically soil-borne diseases in pepper.It is diffcult to control. It caused severe damages with increasing the areas of protected vegetables, especially the solar greenhouses. At the same time, it also can aggravated Fusarium vasinfectum, Mycosphaerella pinoides,and other soil-borne fungal diseases and bacteriosis.The smoked soil of methyl bromide fumigation or highly toxic and high residual chemicals was used to controlling root-knot nematodes in production.However, they not only caused vegetable products degradation and polluted the environment serevely,but also led the greenhouse soil to extremely degenerate. So the use of resistant pepper cultivars was the most economic and effective method to control this disease.Conventional breeding methods need to consume long time, but the rapid development of molecular markers will greatly shorten the breeding term. Therefore,constructing the genetic linkage map of root-knot nematodes resistance genes is important for marker-assisted breeding in pepper.This study used the resistant inbred lines'HDA149'with Me3 gene as male parent and the susceptible inbred lines'8214'as female parent to build a mapping population which included 2133 F2 progenies. Based on the initial locating of predecessors, we constructed a fine mapping for Me3 gene by using BSA.The main results are as follows:1. This study used 520 pairs of SSR primers, two pairs of SCAR primers, two pairs of SSCP primers and one pair of CAPS primers to screen polymorphism. There were 284 pairs of SSR primers and 1 pairs of SSCP primers with polymorphism between two parents.The polymorphic ratio was 54.29%.2. There were only two pairs of primers (SSCP_B322 and EPMS658) with stable polymorphism between two pools,by using Resistant and susceptible pools to screen the 285 pairs of primers.3. F2 individuauls were amplified with these two pairs of primers, recording the analytic data.We constructed a molecuoar linkage map by using JoinMap3.0 softwar.SSCP_B322 and EPMS658 markers were located on both sides of Me3 e,with their genetic distances of 0.56 cM and 1.33 cM,respectively. 4. SSCP_B322 and EPMS658 markers had been verified in BC1S,BC1H and F3 populations,which could be effectively used to root-knot nematode resistant breedding in pepper(Capsicum annuum L.).