Abstract
BackgroundThinopyrum intermedium (2n = 6x = 42) is an important wild perennial Triticeae species exhibiting many potentially favorable traits for wheat improvement. Wheat-Th. intermedium partial amphiploids serve as a bridge to transfer desirable genes from Th. intermedium into common wheat.ResultsThree octoploid Trititrigia accessions (TE261–1, TE266–1, and TE346–1) with good resistances to stripe rust, powdery mildew and aphids were selected from hybrid progenies between Th. intermedium and the common wheat variety ‘Yannong 15’ (YN15). Genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH) and multicolor GISH (McGISH) analyses demonstrated that the three octoploid Trititrigia possess 42 wheat chromosomes and 14 Th. intermedium chromosomes. The 14 alien (Th. intermedium) chromosomes belong to a mixed genome consisting of J-, JS- and St-genome chromosomes rather than a single J, JS or St genome. Different types of chromosomal structural variation were also detected in the 1A, 6A, 6B, 2D and 7D chromosomes via FISH, McGISH and molecular marker analysis. The identity of the alien chromosomes and the variationes in the wheat chromosomes in the three Trititrigia octoploids were also different.ConclusionsThe wheat-Th. intermedium partial amphiploids possess 14 alien chromosomes which belong to a mixed genome consisting of J-, JS- and St- chromosomes, and 42 wheat chromosomes with different structural variations. These accessions could be used as genetic resources in wheat breeding for the transfer of disease and pest resistance genes from Th. intermedium to common wheat.
Highlights
IntroductionAgropyron intermedium (Host) Beauvor and Elytrigia intermedia (Host) Nevski] (2n = 6x = 42; genome formula EeEeEbEbStSt, JJJSJSStSt, EEVVStSt or JrJrJvsJvsStSt) is considered as a segmental autoallohexaploid, and its genome constitution hanging in doubt is a research hot subject in Triticeae crop research
Thinopyrum intermedium (2n = 6x = 42) is an important wild perennial Triticeae species exhibiting many potentially favorable traits for wheat improvement
The Genomic in situ hybridization (GISH) (Fig. 1-A1) and fluorescence in situ hybridization (FISH) (Fig. 1-A2) results indicated that TE261–1 contained 42 wheat chromosomes and 14 Th. intermedium chromosomes (Fig. 2), including one pair of St-genome chromosomes that were completely labeled with probe signals, one pair of J-genome chromosomes labeled only in the telomeres, three pairs of JS-genome chromosomes with obvious labeling in centromere areas, one pair of acrocentric chromosomes from the JS genome, and one pair of J-St translocated chromosomes
Summary
Agropyron intermedium (Host) Beauvor and Elytrigia intermedia (Host) Nevski] (2n = 6x = 42; genome formula EeEeEbEbStSt, JJJSJSStSt, EEVVStSt or JrJrJvsJvsStSt) is considered as a segmental autoallohexaploid, and its genome constitution hanging in doubt is a research hot subject in Triticeae crop research. Ji et al concluded that the genome constitution of Th. intermedium is EeEeEbEbStSt by using multicolor GISH (McGISH) [5]. Analyzing the chloroplast trnL-F sequence, granule-bound starch synthase I (GBSSI) and GISH, Mahelka et al (2011) inferred that genomes of Th. intermedium are related to Ps. strigosa (StSt), Dasypyrum villosum (2n = 14, VV), and a complex origin from Th. elongatum (EE) and Aegilops tauschii (2n = 14, DD) [6]. JrJrJvsJvsStSt was proposed by Wang et al, who made use of EST-SSR markers to analyze the genome evolution of Th. intermedium, and Jr and Jvs refer to ancestral genomes of Je(E) and Jb(J), respectively [7]
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