Development And Molecular Marker Analysis Of Chromosome 2R Variations Of Secale Cereale Cv. Jingzhouheimai

Chinese rye cultivar Jingzhouheimai found in Hubei province confers resistance to several important wheat diseases, making it a useful resource for wheat improvement. Its chromosome 2R was reported with genes resistance for wheat powdery mildew and wheat spindle streak mosaic virus (WSSMV). Screening of Jingzhouheimai chromosome 2R specific markers, development of chromosome variations via marker assisted selection and GISH analysis and mapping the resistance genes to the segments of 2R would be helpful for transferring, mapping, and utilizing these resistance genes in wheat.In this study,2571 primers were used for screening specific markers for chromosome 2R via amplifying in wheat landrace Huixianhong, rye cv. Jingzhouheimai, Huixianhong-Jingzhouheimai amphiploid (JH 1), and Huixianhong-Jingzhouheimai 2R disomic addition line (H-J DA2R-1), which allowed the identification of 30 2R markers (including twenty-two EST marker and eight SSR markers). The DA2R-1/Huixianhong F2 population was then screened for variations of chromosome 2R by these markers.25 plants with only 2RL markers Xscm75, not with 2RS markers Xscm32 were characterized via GISH as each added one telosome 2RL (designated MtA2RL), while 29 plants with only 2RS markers Xscm32, not with 2RL markers Xscm75 were characterized via GISH as each added one telosome 2RS (MtA2RS). Both DtA2RS and DtA2RL were then identified from the selfed progenies of MtA2RS and MtA2RL plants. Then 19 2R marker (Xz100, Xscm38, Xscm71, Xscm75, Xscm99, Xscm119, Xscm149, Xz514, Xz917, Xz919, Xksm16, X2EST-62, Xz1062, Xz1075, Xz1080, Xz1121, XWXE342, XWXE358, and XWXE389) are mapped on 2RL,112R marker (Xscm32, Xscm33, Xscml53, Xz74, Xz248, Xz268, Xz536, Xz667, Xz805, Xedm23 and Xedm70) are mapped on 2RS.The DA2R-1/Huixianhong F1, and F2-F3 population were characterized by both specific markers for 2R and powdery mildew resistance identification. The results showed that 25 F2 plants with 19 2RL markers (including 32 plants with intact 2R) were resistant to powdery mildew, while the other 29 plants only with 11 2RS or without any 2R markers were sensitive, indicating the powdery mildew resistance gene was located on the long arm of 2R. A heterozygous translocation TW-2RL plant with resistance was also developed. WSSMV identification and marker analysis on 33 F4 lines of DA2R-1/Huixianhong revealed that 15 of 17 plants with five 2RL markers were resistant indicating a resistance locus might be contained in 2RL.Of the 30 markers specific for 2R,11 were physically mapped and 10 were on wheat group 2 chromosomes and 1 on group 3 chromosomes after analyzed in wheat Chinese Spring nulli-tetrasomics and deletions. In silico mapping of these markers on rice and Brachypodium genomes revealed that chromosome 2R shared higher synteny with rice chromosome R4, R7 and Brachypodium chromosome Bd5 and Bdl.From DA2R-1/Norin 26-Aegilops triuncialis DA3C F2, the other 15 chromosome variations were identified with 2R specific markers. Comparison of positions of these markers on these variations revealed that Xedm23 in the centromeric region of chromosome 2R. Two markers (Xscm32 and Xscm33) always appear or disappear in the same variations indicating close distance.