Molecular Cytological Identification Of Wheat-Thinopyrum Intermedium Introgression Line With Fusarium Head Blight

Wheat（Triticum aestivum L.AABBDD,2n=6x=42）belongs to the genus Triticum of Gramineae and is one of the most important food crops in the world.Its caryopsis serves as the staple food of human beings and provides the main food source for about 30%of the global population.In the traditional breeding process,breeders mainly select high-quality wheat varieties through hybridization and directional selection among wheat varieties,which reduces the genetic diversity of wheat and causes frequent outbreaks of wheat diseases.Common wheat has a narrow germplasm base and is vulnerable to biotic and abiotic stresses.This narrow gene pool greatly limits the opportunity to develop genetic resistance to disease.Wild related species of wheat provide a valuable gene pool for improvement of varieties through distant hybridization.Thinopyrum intermedium is easy to cross with wheat,and its genes such as disease resistance and stress resistance are introduced into the genetic background of wheat,which enriches the genetic diversity of wheat and cultivates new resistant germplasm resources.In this study,the octoploid Triticum aestivum TAI8045 and TAI8335 from Thinopyrum intermedium,which are resistant to FHB,were used as bridge parents,and the susceptible common wheat varieties were used as recipient parents,and then backcrossed with wheat parents in their F₁ generation,and then a stable BC₁F₈ progeny family was obtained after continuous self-crossing.64 materials from BC₁F₈ progeny families were inoculated with MC-7 by single floret inoculation method to identify their resistance to FHB.The results showed that 16 materials were highly resistant to FHB,29materials were moderately resistant,7 materials were moderately susceptible,and 12materials were highly susceptible to FHB.The screened resistant materials can enrich wheat disease-resistant resources and further cultivate excellent disease-resistant varieties by using them.A high FHB resistance material CH74 and a high FHB sensitivity material CH51were selected from the above BC₁F₈ progeny family materials for fluorescence in situ hybridization and molecular marker identification,respectively,and the source of FHB resistance genes was analyzed and inferred through the foreign chromosomes they contained.Chromosome production of root tip cells showed that the number of CH51chromosomes was 42 and the number of CH74 chromosomes was 44.GISH analysis of CH51 and CH74 was carried out by using the genome DNA of Pseudorogneria spicata as probe and the genome DNA of CS as blocking agent.The results showed that CH51contained 40 wheat chromosomes and 2 Thinopyrum intermedium chromosomes which showed strong hybridization signals in the telomere region of the whole short arm and long arm,and there was translocation between J^s-and St-genome chromosomes.CH74contained 42 wheat chromosomes and 2 J^s-chromosomes which showed strong hybridization signals in the telomere region and centromere region of the whole short arm and long arm.The FISH results with Oligo-p Sc119.2 and Oligo-p Ta535 as probes showed that CH51 contained 40 wheat chromosomes and a pair of homologous chromosomes which replaced the 6B chromosome of wheat,and CH74 contained 42 wheat chromosomes and a pair of 1J^schromosomes derived from Thinopyrum intermedium.The experimental results showed that CH51 was a wheat-Thinopyrum intermedium diploid translocation substitution line and CH74 was a wheat-Thinopyrum intermedium diploid alien addition line.CH51 was identified by 47 STS markers of Thinopyrum intermedium Group6.According to the amplification results,8 specific molecular markers on Thinopyrum intermedium 6J^s chromosome and 4 specific molecular markers on 6St chromosome were screened out.CH74 was identified by 98 STS markers of Thinopyrum intermedium Group1.According to the amplification results,8 specific molecular markers on Thinopyrum intermedium 1J^s chromosome were screened out,it was further inferred that Group6-Chr.1 was the 6J^s chromosome of Thinopyrum intermedium and Group1-Chr.3 was the 1J^s chromosome of Thinopyrum intermedium.To sum up,CH51 belongs to wheat-Thinopyrum intermedium diploid translocation substitution line,and its wheat 6B chromosome is replaced by Thinopyrum intermedium chromosome,and there was translocation between J^s-and St-genome chromosomes,while CH74 contains a pair of 1J^s chromosomes of Thinopyrum intermedium belonging to alien addition line.Combined with the results of FHB resistance identification,it can be inferred that 1J^s of Thinopyrum intermedium contains FHB resistance genes,and 20selected markers can be used as specific STS molecular markers for chromosomes of Thinopyrum intermedium 6J^s、6St and 1J^s,respectively.