[Identification of the 1RS-7DS.7DL wheat-rye small segment translocation lines].

Rye (Secale cereale L., RR) is a valuable genetic resource for the improvement of common wheat (Triticum aestivum L., AABBDD). Transferring alien rye genes into wheat by distant hybridization and automatic chromosome doubling is an important and efficient method to boost agronomic traits, disease resistance and widening the gene pool in wheat. In this study, an octoploid triticale CD-13 (AABBDDRR) was obtained via automatic chromosome doubling by crossing landrace Penganbaimaizi (T. aestivum L., AABBDD) and rye "Qinling rye" (S. cereale cv. Qinling, RR). GISH and FISH analyses indicated that CD-13 contained a 1RS-7DS.7DL wheat-rye small segment translocation chromosome. In order to transfer the 1RS-7DS small segment translocation into hexaploid wheat, 58 lines of the F5 inbred population from the cross CD-13 x Chuanmai 42 were screened for rye chromosome segments by GISH and FISH analyses. The results showed that 13 lines contained the 1RS-7DS.7DL small segment translocation chromosome by reciprocal translocation between 1RS and 7DS. These translocation lines carrying 1RS small rye alien segment were tested for the translocation breakpoints and the presence of a storage protein locus Sec-1. The Sec-1 locus was absent in the line 811, a stable 1RS-7DS.7DL small segment translocation line. The translocation breakpoint of 1RS-7DS.7DL of this line was located in the interval of IB267-IAG95 around the telomere of 1RS chromosome. Thousand-kernel weight of the line 811 was much higher than the parent CD-13, but not significantly different from Chuanmai 42. This indicated that 1RS-7DS.7DL small segment translocation had no negative effect on thousand-kernel weight in the genetic background of Chuanmai 42. The line with 1RS-7DS.7DL translocation chromosomes can be used as a new genetic material for further studies of valuable genes and their genetic effect on 1RS small segment.

[Genetic analysis and molecular mapping of stripe rust resistance gene in a restore line of Thermo-Photo sensitive hybrid wheat MR168].

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is an important limiting factor to popularize hybrid wheat. The objectives of this study were to map a stripe rust resistance gene in a Chinese thermo-photo-sensitive hybrid wheat restore line MR168 using gene postulation and SSR markers. MR168 was highly resistant to 23 Pst races including CYR29, CYR31, CYR32, and CYR33. The populations F1, BC1, F2, and F3 from the cross between MR168 and SY95-71 (a wheat cultivar susceptible to Pst races) were inoculated with the race of Pst CYR32 of China in greenhouse. MR168 carried a single dominant gene for resistance to CYR32, tentatively designated YrMR168. It originated from Liaochun 10, a spring wheat variety. A total of 183 F2 plants, the resistant and susceptible parents and resistant and susceptible bulks were used for resistance gene mapping with 329 pairs of wheat SSR markers.Five SSR markers on chromosome 1BS including Xgwm18, Xbarc187, Xwmc269, Xgwm273, and Xwmc406 were linked with YrMR168. The resistance gene was closely linked to Xgwm18 and Xbarc187 with the genetic distances of 1.9 and 2.4 cM, respectively. Xgwm18 and Xbarc187 could be used for molecular marker assisted selection of YrMR168 in hybrid wheat breeding program.

[Genetic diversity analysis of the developed Qingke (hulless barley) varieties from the plateau regions of Sichuan Province in China revealed by SRAP markers].

Genetic diversity of 25 accessions of Qingke (hulless barley) varieties from the plateau regions of Sichuan Province, China, was analyzed by using SRAP (Sequence-related Amplified Polymorphism) markers. The results showed that 64 pairs of primer combinations produced 999 clear bands, of which 62 primer pairs (96.9%) amplified 225 polymorphic bands (22.5%). Three hundred and thirty three allelic phenotypes were amplified with an average of 5.20 alleles/primer pair. The genetic diversity ranged from 0 (me9/em14, me9/em15) to 0.8928 (me6/em18) with an average of 0.5126. The 25 accessions were classified into three major groups: A, B, and C by cluster analysis using UPGMA, which showed significant relationship with the origin regions of accessions. Thus, it was suggested that the Sichuan hulless barleys could be used as elite germplasms to enhance the genetic background for super-hulless barley breeding.

Inheritance and expression of stripe rust resistance in common wheat (Triticum aestivum) transferred from Aegilops tauschii and its utilization.

Stripe rust is one of the most destructive diseases for wheat crops in China. Two stripe rust physiological strains, i.e. CYR30 (intern. name: 175E191) and CYR31 (intern. name: 293E175) have been the dominant and epidemic physiological strains since 1994. One Aegilops tauschii accession (SQ-214) from CIMMYT was found immune from or highly resistant to Chinese new stripe rust races CYR30 and CYR31 at adult stage. SQ-214 was crossed with a highly susceptible Ae. tauschii accession As-80. Analysis of data from F1-F2 populations of SQ-214/As-80 revealed that the resistance was controlled by a single dominant gene. To exploit the resistance for wheat breeding, SQ-214 was crossed with Chinese Spring (CS) and backcrossed by two Chinese commercial wheat varieties MY26 and SW3243. The resistance from SQ-214 was suppressed in the F1 hybrids (CS/SQ-214) and the F2 population of CS/SQ-214//MY26. However, the resistance of SQ-214 was expressed in several F2 individuals of CS/SQ-214//SW3243. Eleven advanced lines with high level of resistance to the Chinese stripe rust CYR30 and CYR31 have been developed. This result suggested that SW3243 does not suppress the expression of the Chinese stripe rust and should be used as wheat germplasm for exploiting resistance of Ae. tauschii in wheat breeding. The gliadin electrophoretic pattern of the eleven advanced lines with high stripe rust resistances was compared with their parents SQ-214, CS and SW3243 by acid polyacrylamide gel electrophoresis. The omega-gliadin bands of Gli-Dt1 in Ae. tauschii SQ-214 were transferred to some advanced lines and freely expressed in common wheat genetic background. One of advanced lines possesses a null Gli-D1 allele, where the omega-gliadin bands encoding by the Gli-D1 allele were absent. The potential utilization of this advanced line for wheat quality and stripe rust resistance breeding is also discussed in this paper.