Genetic Analysis And Molecular Marker Study Of A Novel Dwarfing Gene In Wheat-Thinopyrum Ponticum Germplasm Line

Transfering the desirable genes of wheat related species into wheat can make up for insufficient resources of conventional breeding and creat new gerplasm resources. The dwarf germplasm lines Shannong31504-2, 31504-3 and 31505-1 was selected from filial generation of Thinopyrum ponticum, and was identified as good new short source. In this esperiment, the morphology, cytology, molecular level methods were used to identify the short source. The results are showed just as follows:(1) Materials 31504-2, 31504-3 and 31505-1 were selected from progeny of 31504 and 31505. They are about 50cm high, different from each other especially the ear charachers. Their dwarf genes were confirmed to be not sensitive to gibberelines by identification.(2) The results indicated that the chromosome number were 2n = 42. Most of the pollen mother cell have 21 bivalents which demonstrate cytologically stable. The result of GISH (using the probe with genes of Thinopyrum ponticum) showed: 31505-1 was substitution of wheat-thinopyrum, but 31504-2 and 31504-3 did not detect green hybridization signal. This could be due to translocation segment is too small.(3) The 2Ee-1F/R specific markers could amplified special bands of Thinopyrum ponticum.I speculated that the exgenous DNA fragment carring dwarf genes have relative with the second homologous group.(4) Crosses between 31504-2 and high material Chinese spring indicated that the plant heights of F1 hybrids were the mid-parent value, and F2 have three types: dwarf stalk (<70cm), middle stalk (70-100cm), high stalk (>100cm). The F2 segregating population was 1:2:1, showing the awarf trait was controlled by one partial dominant gene.(5) 2700 genomic SSR, EST-SSR and STS primers were screened for polymorphic markers in Chinese spring and 31504-2, gain 4 SSR markers and 3 STS markers. F2 population verification, recorded the banding pattern. Using Mapmaker3.0 software, we constructed 72.8cM genetic maps. The markers sequence is as followes: Xwmc41–Xmag4059–Xmag3596–Xcfd168–Xcfd267–Xmag1280–Xwmc18. (6) The result of QTL detection indicated that a important effect genes lacated between marker Xwmc41 and Xmag4059. The genetic distance between them was 7.4cM and 11.4cM. Because Xwmc41, Xcfd168 and Xwmc18 had been lacated on chromosom 2DL, Xmag4059, Xmag3596, Xmag1280 had been lacated on chromosome 2D, indicating that dwarf genes of 31504-2 was located on 2DL.(7) By using Thinopyrum ponticum, Chinese spring, 31504-2 and 31504-3 for PCR, the result were as follows: genes between Xwmc41 and Xmag3596 are come from Thinopyrum ponticum, as the Thinopyrum ponticum and 31504-2 have the same bands when use Xwmc41, Xmag4059 and Xmag3596.