Molecular Cytogenetic Identification Of Wheat-Thinopyrum Intermedium Substitution Addition Line 13-337

Common wheat is one of the most significant crops. The key factor to influence yield and quality is breeding level. In recent years, the genetic basis of wheat becomes narrow and limits the improvement of the quality and production of wheat. Thinopyrum intermedium (2n=42, JJJ J StSt), which carries many desirable genes for wheat improvement, can be used as important parent crossed with common wheat to broad the genetic diversity of wheat and transfer the desirable genes into common wheat.A stable wheat line 13-337 was studied in this research which was derived from cross between "Chuan Mai 107" (CM 107) and wheat-Thinopyrum intermedium partial amphiploid TAI7045. The evaluation of agricultural traits, somatic chromosome count and meiosis analysis, in situ hybridization and PLUG marker analysis of line 13-337 were carried out. Results are as follows:1. The results of agricultural traits between line 13-337 and its recurrent parent CM107 indicated the plant height, spike lengh and effective tiller number of line 13-337 resembled CM107, while both kernel number per spike and thousand kernel weight were half of those of CM 107 and kernel shape of line 13-337 which was significantly different from that of CM107 was similar to the kernel trait of Thinopyrum intermedium.2. Root-tip chromosome count showed that line 13-337 contained 2n=44 chromosomes, which suggested it is an addition line. In meiotic metaphase I,22 bivalents was observed in most of pollen mother cells, while two univalents and 21 bivalents in very few pollen mother cells of line 13-337 were also found. The result demonstrated line 13-337-1 was almost cytogenetically stable.3. Genomic in situ hybridization (GISH) and sequential in situ hybridization were porformed in this study. Using genomic DNA of Th. intermedium and Pseudoroegneria strigosa as probes respectively, GISH analysis showed that two pairs of chromosomes from Th. intermedium were transfered into line 13-337. One pair of alien chromosomes belonged to J genome, while the other pair chromosomes were St-Js translocation between St and Js genome chromosomes of Th. intermedium. But we still can not make sure the translocation breakpoint of St-Js chromosomes. Sequencial fluorescence in situ hybridization (FISH) and multicolor genomic in situ hybridization (mGISH) were carried out sequencially. Using pAs1 and pScl19.2 as probes, FISH analysis showed that a pair of 4D chromosomes missed in line 13-337. The results of mGISH with mixed DNA probes of Triticum urartu, Aegilops speltoides and Th. intermedium and block DNA of Aegilops tauschii were further verified that line 13-337 was an substitution addition line.4. Two PLUG primers can amplified specific fragments of line 13-337. PLUG markers TNAC1457 which located in 4DS2-0.82-1.00 did not amplify the specific fragments of 4D, but the same specific segments of line 13-337, Th. intermedium, Ps. spicata and Th. Bessarabicum were produced. The specific fragments of 4D were also missing with PLUG markers TNAC1412 which located in 4DL11-0.61-0.71, however, a same fragments among line 13-337 and Ps. Spicata was amplified. These results demonstrated that one pair of 4D chromosomes of line 13-337 were substituted by 4St-Js translocation chromosomes and the pair of J chromosomes were added. Therefore, line 13-337 was a substitution addition line whose a pair of 4D chromosomes was substitued by a pair of 4St-Js chromosomes and one pair of J chromosomes was added.