In order to increase the supply of assimilated carbon to grain, a new stay-green wheat cultivar, Chuannong17 (CN17), with delayed leaf senescence, carrying wheat-rye 1RS.1BL translocated chromosome was developed. CN17 exhibited distinct differences in net photosynthetic rate (P_n), chlorophyll (Chl) content, malondialdehyde (MDA) content, activity of both superoxide dismutase (SOD) and catalase (CAT) during the grain filling stage, and flag leaf senescence compared with the control. The new cultivar maintained longer and higher photosynthetic competence compared with the control, and this aspect correlated with the difference in chloroplast development. Moreover, the stay-green phenotype of CN17 was also observed under natural growth conditions. Consequently, the coordination of the physiological, biochemical, and structural aspects in the stay-green cultivar produced higher seed weights and per-plant yield compared with the control cultivar.

The chromosome arm 1RS of rye (Secale cereal L.) has been used worldwide as a source of genes for agronomic and resistant improvement. However, the 1RS arm in wheat has end-use quality defects that are partially attributable to the presence of ω-secalins, which are encoded by genes at the Sec-1 locus. Various attempts in removing the Sec-1 genes from the 1RS.1BL translocation chromosome have been made. In the present study, two new primary 1RS.1BL translocation lines, T917-26 and T917-15, were developed from a cross between wheat variety “A42912” and Chinese local rye “Weining.” The lines T917-15 and T917-26 carried a pair of intact and homogeneous 1RS.1BL chromosomes. The line T917-26 also harbored an expression deletion of some genes at the Sec-1 locus, which originated from a mutation that occurred simultaneously with wheat-rye chromosome translocations. These results suggest that the accompanying mutations of the evolutionarily significant translocations are remarkable resources for plant improvement. Comparison of translocation lines with its wheat parent showed improvements in the end-use quality parameters, which included protein content (PC), water absorption (WA), sodium dodecyl sulfate sedimentation (SDSS), wet gluten (WG), dry gluten (DG) and dough stickiness (DS), whereas significant reduction in gluten index (GI) and stability time (ST) were observed. These findings indicate that 1RS in wheat has produced a higher amount of protein, although these comprised worse compositions. However, in the T917-26 line that harbored an expression deletion mutation in the Sec-1 genes, the quality parameters were markedly improved relative to its sister line, T917-15, especially for GI and DS (P < 0.05). These results indicated that expression deletion of Sec-1 genes significantly improves the end-use quality of wheat cultivars harboring the 1RS.1BL translocation. Strategies to remove the Sec-1 genes from the 1RS.1BL translocation in wheat improvement are discussed.

Secale cereale is used as a source of genes for disease resistance in wheat cultivation. In this study, a homozygous translocation line (RT14-245) that originated from a cross between a commercial wheat cultivar (Mianyang 11) and a local Chinese variety of rye (Baili) was developed. Multicolor fluorescence in situ hybridization and PCR analysis demonstrated that the translocation chromosome was 7BS.7RL. Resistance analysis showed that RT14-245 was resistant to prevalent pathotypes of stripe rust and powdery mildew. RT14-245 also exhibited high resistance to Fusarium head blight, which was similar to the resistance exhibited by the wheat cultivar Sumai 3. The results indicated that RT14-245 simultaneously exhibited high levels of resistance against stripe rust, powdery mildew, and Fusarium head blight. These results indicate that chromosome arm 7RL in the translocation line RT14-245 is an excellent new resource for wheat breeding programs.

Secale cereale L. has been used worldwide as a source of genes for agronomic and resistance improvement. In this study, a stable wheat-rye substitution line and 3 primary 1RS.1BL translocation lines were selected from the progeny of the crossing of the Chinese local rye Aigan variety and wheat cultivar Mianyang11. The substitution and translocation lines were identified by molecular cytogenetic analysis. PCR results, fluorescence in situ hybridization and acid polyacrylamide gel electrophoresis indicated that there were a pair of 1R chromosomes in the substitution line which have been named RS1200-3, and a pair of 1RS.1BL translocation chromosomes in the other 3 translocation lines, which have been named RT1163-4, RT1217-1, and RT1249. When inoculated with stripe rust isolates, these 4 lines expressed high resistance to several Puccinia striiformis f. sp Tritici pathotypes that are virulent on Yr9. Moreover, the different response pattern of resistance among them suggested that the diversity of resistance genes for wheat stripe rust exists in the rye. These 4 lines also showed better agronomic performances than their wheat parent. The GS indices also showed the genetic diversity of the 1RS which derived from same rye variety. The present study indicates that rye cultivars may carry untapped variations that could potentially be used for wheat improvement.

Non-denaturing fluorescence in situ hybridization (ND-FISH) has been used to distinguish wheat chromosomes and to detect alien chromosomes in the wheat genome. In this study, five different oligonucleotide probes were used with ND-FISH to examine 21 wheat cultivars and lines. These oligonucleotide probes distinguished 42 wheat chromosomes and also detected rye chromatin in the wheat genome. Moreover, the signal patterns of the oligonucleotide probes Oligo-pTa535-1 and Oligo-pSc119.2-1 showed high polymorphism in the wheat chromosomes. A total of 17.6% of the A group chromosomes, 25.9% of the B group chromosomes and 8.9% of the D group chromosomes showed obvious mutations when they were compared to the standard ND-FISH signal patterns, and most of them were Oligo-pSc119.2-1 mutants. The results suggested that these polymorphisms could be induced by the crossing of wheat cultivars. The results provided more information for the further application of oligonucleotide probes and ND-FISH.