Molecular Cytogenetic Analysis Of Chinese Winter Wheat Germplasm Aimengniu

The renowned winter wheat genmplasm Aimengniu(AMN) derived from the cross combination Aifeng3/JMengxian2ol/Neuzucht has widely been used in Chinese wheat breeding and production. To date, more than 13 cultivars and numerous advanced lines have been developed from the cross combinations involving this germplasm. In order to clarify the genetic characteristics, chromosome constitution of AMN, its 6 major types (Type 11 -VII) were examined through mitotic chromosome C-banding and Genomic in situ hybridization (GISH). The results indicated that AMN II, IV, V, VI involve a new wheat-rye complex translocation which is probably resulted from a reciprocal translocation between IRS ?1BL and wheat chromosome 7D. It was desiganated as to be IRS ?7DS, I BL ?7DL. The results also indicated that the translocation contained in AMN VII is an usual 1RS ?1BL and no translocation between wheat-and iye was found in AMN Ill. To confirm the new wheat-rye complex translocation, a I BL ?IRS translocation line AMN VII and ditelosomic 7DL of Chinese Spring were crossed to AMN II,, IV, V and VI, respectively, chromosome configuration at PMC MI of the hybrids F1 were examined by chromosome C-banding and GISH. As expected, a tetravalent occurred in each combimtion between 1RS IBL and 1RS?7DS,1BL?7DL lines and in the cross combination AMN VII/AMN V. the mean chromosome configuration is O.091+15.36?+3.59 In1 +0.73@+0.27 ~.; The Chinese Spring ditelosomic 7DL paired with lB and IBL ?7DL to form a heterotypic trivalent, and another 3 translocated chromosome IRS ~ 7DS always existed as a univalent. The mean chromosome configuration inAMN VIXC.S dt 7DL was 0.04€) +0.04 ~+1.0O i~i+ 14.88 ?+3.83 ~ +1.171.. Therefore, the new wheat-rye complex translocation designated as IRS 7DS, 1BL 7DL, in AMN II, IV, V and VI, could be explained as to be reciprocal translocation between IRS ?1BL and 7D. In order to understand its genetic transmission clura~teristics, a set of RILs developed from the cross between 1RS 7DS, IBL 7DL and IBL IRS tmnslocation lines, and 8 AMN dezivatives were analyzed by mitotic chmmosome C-banding. Of the 109 lines surveyed, 69 lines contained the honiozygous complex translocation, 36 with homozygous IBL iRS and ~on1y four lines were heterozygous. 6 out of the 8 AMN derivatives (75%) contained iRS 7DS, 1BL?7DL, one cultivar proved to be exclusively 1BL iRS and anotha~ one showed regular chromosome constitution. In conclusion, the new wheat-rye complex translocation discovered in AMN not only can readily transmit to its derivatives but also show higher transmission rate than thatoflBL IRS. To enhance the resistanee of AMN to powdery mildew and yellow rust diseases, 4 6VS ?6AL translocation line containing Pm21 and new rust-resistance genes developed by cytogenetics Institute, Nanjing Agricultural University, China has been crossed to 1BL IRS and 1RS 7DS, 1BL 7DL lines, respectively. By chromosome C-banding and multi color GISH , the multiple translocation hoinozygotes of 1RS IBL, 6VS 6K , or 1RSe 7DS, 1BL 7DL, 6VS 6AL have been confirmed. The iRS 1BL, 6VS 1AL lines showed regular chromosome conf~uration at PMC MI. All the multiple translocation lines had both desirable agronomic traits and powdery mildew resistance.