| Thinopyrum ponticum(2n=10x=70)is a kind of perennial wild relatives of wheat in the genus Elytrigia.It has excellent traits such as cold and drought resistance,salt and alkali resistance,developed root system,and high resistance to major wheat diseases.It is an ideal genetic resource for wheat genetic improvement.It is an important way to broaden the genetic basis of wheat to transfer the excellent genes of Th.ponticum repens to wheat by distant hybridization.In this study,two wheat-Th.ponticum derivatives CH18067 and CH20015 with stripe rust resistance were screened,and they were comprehensively identified by molecular cytogenetics.The main results are as follows:(1)The observation of root tip cells showed that the chromosome number of CH18067was 42.The results of pollen mother cell observation showed that the chromosome configuration of CH18067 meiotic metaphase I was 2n=21II,and it could be equally separated at the late stage of meiosis,indicating that it had genetic stability.FISH and GISH identified2D and 4D chromosome deletions in CH18067,and two pairs of Th.ponticum chromosomes.Mc-GISH identification showed that these two pairs of chromosomes were derived from the J genome and the J~S genome,respectively.In the molecular marker analysis,six polymorphic markers located in the second part of the homologous group and the fourth part of the homologous group amplified the specific bands of Th.ponticum in CH18067.CH495-2 is a hybrid offspring of CH18067 and common wheat Abbondanza.Through in situ hybridization and molecular marker analysis,CH495-2 was identified to contain a pair of 2J chromosomes,so it was clear that the J genome chromosome in CH18067 belonged to the second homologous group,while the J~S genome belonged to the fourth homologous group.In the detection of wheat-Th.elongatum liquid chip(Geno Baits?Wheatplus EE),the signal of CH18067 was absent on 2D and 4D chromosomes,and the signal was significantly enriched on 2E and 4E chromosomes.Based on the comprehensive identification results,CH18067 was identified as a double substitution line of wheat-Th.ponticum 2J(2D)+4J~S(4D),and the FISH karyotypes of2J and 4J~S chromosomes under Oligo-p Ta535 probe were obtained.CH18067 is immune to stripe rust at adult stage,and has the related traits of short rod and long grain,which has the potential for further utilization.(2)The results of cytological observation showed that the chromosome number of CH20015 somatic cells was 44,the chromosome configuration of pollen mother cell meiosis metaphase I was 2n=22II,and it could be separated equally in meiosis anaphase I,which had genetic stability.The results of in situ hybridization showed that CH20015 contained 40common wheat chromosomes,one pair of 2A chromosomes was deleted,and two pairs of J genome chromosomes from Th.ponticum were found.In the molecular marker analysis,nine polymorphic markers located in the second part of the homologous group and the sixth part of the homologous group amplified the specific bands of Th.ponticum in CH20015.In the wheat-Th.elongatum Geno Baits?Wheatplus EE chip detection,CH20015 signal was missing on chromosome 2A,and the signal was significantly enriched on chromosomes 2E and 6E.Based on the results of comprehensive identification,it was confirmed that the 2J chromosome in CH20015 replaced the 2A chromosome and attached a pair of 6J chromosomes,which was a wheat-Th.ponticum 2J(2D)+6J alien addition substitution line.By comparing the FISH karyotype of chromosome 2J in CH18067,the hybridization signal formed by chromosome 6J with Oligo-p Ta535 probe was further determined.In the identification of disease resistance,CH20015 showed certain resistance to stripe rust and scab,and could be further used to create translocation lines or introgression lines.The genetic composition of CH18067 and CH20015 was determined by comprehensive identification,which could be used as candidate germplasm materials for wheat disease resistance breeding and genetic research. |
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