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| Molecular Cytogenetic Identification of Wheat-rye (Triticum aestivum-Secale cereale) 1BL/1R Translocation Line 7-1 with Sharp Eyespot Resistance |
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Abstract Rye(Secale cereale), which contains excellent resistance and stress tolerance genes to against biotic and abiotic stress, is an important germplasm for wheat (Triticum aestivum) improvement. To enlarge the germlplasm resources for wheat breeding, the crosses between common wheat cv. W770B (2n=6x=42, AABBDD) and rye (Secale cereale; 2n=2x=14, RR) via wide hybridization was conducted, and several derived lines with great characteristics were obtained after a long-time screening. Then, the toothpicks infected with Rhizoctonia cerealis which cultivated on freshly prepared potato-dextrose agar (PDA) were put in the leaf sheaths of these materials at the five-leaf stage of wheat plants. The plants after inoculation were cultivated in greenhouse for five weeks, and then identified the occurrence degrees and calculated the disease indexes. Derived line 7-1,with a sharp eyespot disease index of 32.8% was selected and identified by toothpick method through several years for improving the accuracy of the identification. In order to figure out the genetic constitution of 7-1, morphological method, cytogenetical method, genomic in situ hybridization (GISH), sequence characterized amplified region(SCAR) markers, simple sequence repeat(SSR) markers and gliadin analysis were conducted in this study. The results of cytogenetics observation of root tip cells and pollen mother cells showed that the number and structure of chromosome of 7-1 were stable and the configuration of 7-1 was 2n=42=21Ⅱ. GISH analyses using rye genomic DNA as probe indicated that 7-1 contained two chromosome arms of rye. The analysis of rye genome SCAR markers showed that D15 and P13LF/R can amplify 900 bp around and 850 bp around rye specific bands both in rye and 7-1. And the analysis of 1RS SCAR markers of rye showed that ω-sec-p1/ω-sec-p2, ω-sec-p3/ω-sec-p4 and IB-267 amplified 1 100 bp around, 450 bp around and 300 bp around rye target bands both in rye and 7-1. Both analysis of rye genome SCAR markers and rye chromosome SCAR markers showed that 7-1 possessed the 1RS chromosome arm of rye. SSR primers on the long arm and short arm of seven wheat homoeologous groups were screened, but only Xgwm264 and Xgwm11, which derived from 1BS didn't amplify corresponding bands. On the contray, the remainging primers from other chromosomes all amplified bands. The analysis of SSR markes showed 7-1 lacked the 1BS chromosome arm of common wheat. Gliadin Analysis showed that secalin characteristic bands were amplified in 7-1. Consequently, 1BS of wheat was substituted by 1RS of rye and the derivative line was confirmed as a 1BL/1RS translocation line. In this study, 7-1 was identified as the 1BL/1RS translocation line with the resistance to sharp eyespot, broadened materials for wheat breeding, and could be provided as a new germplasm resource for sharp eyespot in future.
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Received: 20 August 2017
Published: 25 March 2018
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