Identification Of Novel Wheat-Rye Chromosome 6R Translocation Lines And Analysis Of The Genetic Effects Of Agronomic Traits

Rye(Secale cereale L,2n=14,RR)is one of the wild relatives of wheat.It is highly adaptable to a variety of adverse environmental and climates,it also has evolved to retain a large number of superior genes that wheat does not possess or has lost.Rye provides a rich genetic resource for the improvement of wheat.An effective way to improve wheat is to introduce superior genes from rye into the wheat genetic background to create new types of material with superior traits.Based on this,the thesis focuses on wheat-rye 6R(6D)substitution line(2n=42)radiation progeny M2 and M3 populations as test materials.The population variation trends and transmission patterns under radiation mutagenesis were obtained by precise identification of novel wheat-rye 6R chromosome translocation types and karyotype statistics.The 6R-specific molecular marker analysis and agronomic trait investigation were also carried out.The results are as follows:1.By using multi-color-FISH(mc-FISH),I identified a total of 1663 plants from the D6R(6D)substitution line M2 population.A total of 10 breakpoints were counted on chromosome 6R.Among them,6R-1(13,12.9%)on 6RS,6R-7(20,19.8%)and 6R-9(26,25.7%)on 6RL were the three high frequency breakpoints.The positions of these three breakpoints were all associated with the p Sc200 sequence enriched region.The highest percentage of translocations was found between chromosome 6R and the wheat A genome,with 52.9%.In this study,16 types of wheat-6R Robertson translocations and18 types of wheat-6R non-Robertson translocations were identified,such as homologous translocation 6RS-6BS.6BL,small fragment translocation 5DS.5DL-6RL,1DS.1DL-6R~-,which provide experimental materials and reference values for the subsequent study of related superior genes on 6R.2.By using multi-color-FISH(mc-FISH),I performed cytological identification and transmission analysis of 390 strains of M3 generation material from 13 wheat-6R translocated materials and concluded that:the transmission rate of the three translocated chromosomes was lower compared to the 10 wheat-6R non-centromeric translocations chromosomes.Among the 10 wheat-6R non-centromeric translocations,the two materials with the lowest transmission rate,e494 and e463,were translocated with the wheat 1homologous group.CENH3 marker signal intensity 5DS.5DL-6RL(1.36)>5D(0.68),6RS-1AS.1AL(2.5)>1A(1.03),6RS-2DS.2DL(1.30)>2D(0.63),therefore it is hypothesized that penetration of the 6R fragment into the wheat chromosome affects the expression of CENH3 in the recipient chromosome and thus affects this chromosomal transmission.3.By using IT and SLAF primers for molecular marker analysis of five 6R-derived line materials,I screened 51 primer pairs in 6RS and 19 primer pairs in 6RL.The physical map of the 6R chromosome was also drawn according to the location of the material breakpoints.6RS was divided into 4 segments(6R S1,6R S2,6R S3,6R S4 molecular marker numbers were 9/15/21/6 respectively)and 6RL was divided into 3 segments(6R L1,6R L2,6R L3 molecular marker numbers were 5/3/11 respectively),which can be used for the segmentation of important traits on the 6R chromosome Localization and analysis.4.By observing stripe rust resistance in D6R(6D)substitution line irradiated progeny and combining the results of molecular marker analysis,I localised the stripe rust resistance gene Yr83 on chromosome 6R to the precise FL0.87-1.00 region of 6RL.By analysing the results of agronomic trait surveys in the field,I found that compared to plants without chromosome 6R,plants with chromosome 6R showed an increase in spike length and spikelet number of 19.62%and 46.82%respectively.Plant height increased by 48.12%in plants with one 6R chromosome and 55.90%in plants with two 6R chromosomes,suggesting that there is a dosage effect of the genes associated with the 6R chromosome controlling plant height.In summary,this study completed the screening of broken and translocated line material from D6R(6D)substitution line radiation progeny and the physical mapping of chromosome 6R.It provides a reference value for the application of superior disease resistance genes on chromosome 6R in wheat improvement breeding research.