Genetic Evaluation Of Seveal Newly Synthetic Hexaploid Wheat

The hexaploidwheat（common wheat）was originatedby twotimes allopolypolidization resulting in only a few accessions of the ancient donor species were involved in the evolution.On the other hand,the genetic background of modern wheat is narrower while the utilization of the modern varieties derived from limited key parents.Therefore,exploiting and introgression the elite genes and genetic variations of wheat relatives is an very important way for enhancing the genetic diversity and improving the yield potential,disease resistances and quality of modern cultivated variety.In present paper,27 newly synthetic hexaploid wheats were developed by using turgidum wheat,durum wheat and the F1 of turgidum wheat and durum wheat as female crossed with 16accessions of Aegilops tauschii（SHW1-SHW27）.And the agronomic characters of 27newly SHWs were evaluated.The chromosome structures of three SHWs with good agronomic traits were identified.A set of 219 RILs（F5）was developed by using a euploidy line of SHW-12 with highly resistance to stripe rust as male crossed with an advanced wheat line 10Dan568.Furthermore,genetic foundation of superiority in stripe rust resistance and agronomic traits of synthetic hexaploid wheat SHW-12 were analyzed by using mixed major-genes plus polygenes inheritance.The results are as follows:（1）The average of plant height,spike length,number of spikelet,number of kernels per spike and 1000 kernels weight of 27 newly SHWs ranged from 120.3 to 136.2 cm,12.03-16.8 cm,16.9-20.3,22.2-37 and 26.05-51.75g,respectively.The newly SHWs have advantages on spike length,number of spikelet,grains number per spike and kernels numbers per spike comparing with Syn769,the synthetic wheat donor of Chuanmai 42 and could be new genetic resources for wheat breeding.（2）A total of 252 S₂ lines of three synthetic wheats（SHW-1、SHW-2 and SHW-12）were identified by FISH.Of 252,175 out of 252 lines,shared 69.44%,possessed 2n=42chromosomes,were considered a euploid lines.And 77 lines,shared 30.56%,were aneuploidy with 2n>42 or<42 chromosomes.The frequency of euploid lines in the three SHWs was different.The highest one was SHW-2 with 82.56%,the middle one was SHW-1 with 66.39%,and the lowest one was SHW-12 with 53.19%.A hidden aneuploidy line with one 1Band three 6B,was found in SHW-1.Comparing to Chinese Spring,SHW-2 possessed four differentiation chromosomes（1B,6B,2D and 4D）,while SHW-1had two（1B and 6B）and SHW-12 had four（5A,5B,6B and 2D）.Among the aneuploidy lines of the three SHWs,the phenomenon of chromosome losses and chromosome addition,chromosome broken and translocation were observed.（3）Using RILs derived from SHW-12 and 10Dan568,the stripe rust resistance and yield relative traits were analyzed by mixed major-genes plus polygenes inheritance.The SHW-12 obtained its superiority of breeding in enhancing stripe rust resistance,grains per spike and spikes per plant.In all 4 detected major genes,the alleles enhancing stripe rust resistance were from SHW,and the 1st gene had the strongest additive effect.One of 2detected major genes had the additive effect increasing grains number per spike from SHW.Three of 4 detected major genes for spike number per plant had three favor alleles from SHW while the 1st,2nd genes produced largest additive effects.It dissected the genetic basis of the breeding superiority of SHW.（4）15 elite lines with favor agronomic traits such as semi-dwarf,longer spike,more spikelet and big kernel were selected from the RILs of SHW-12 and 10Dan568,which can be used for wheat breeding program.