Abstract
BackgroundHexaploid triticale could be either synthesized by crossing tetraploid wheat with rye, or developed by crossing hexaploid wheat with a hexaploid triticale or an octoploid triticale.Methodology/Principal FindingsHere two hexaploid triticales with great morphologic divergence derived from common wheat cultivar M8003 (Triticum aestivum L.) × Austrian rye (Secale cereale L.) were reported, exhibiting high resistance for powdery mildew and stripe rust and potential for wheat improvement. Sequential fluorescence in situ hybridization (FISH) and genomic in situ hybridization (GISH) karyotyping revealed that D-genome chromosomes were completely eliminated and the whole A-genome, B-genome and R-genome chromosomes were retained in both lines. Furthermore, plentiful alterations of wheat chromosomes including 5A and 7B were detected in both triticales and additionally altered 5B, 7A chromosome and restructured chromosome 2A was assayed in N9116H and N9116M, respectively, even after selfing for several decades. Besides, meiotic asynchrony was displayed and a variety of storage protein variations were assayed, especially in the HMW/LMW-GS region and secalins region in both triticales.ConclusionThis study confirms that whole D-genome chromosomes could be preferentially eliminated in the hybrid of common wheat × rye, “genome shock” was accompanying the allopolyploidization of nascent triticales, and great morphologic divergence might result from the genetic variations. Moreover, new hexaploid triticale lines contributing potential resistance resources for wheat improvement were produced.
Highlights
Polyploidy is a prominent process in plant speciation, and numerous important crop species are polyploid, most importantly allopolyploid [1,2,3]
This study confirms that whole D-genome chromosomes could be preferentially eliminated in the hybrid of common wheat × rye, “genome shock” was accompanying the allopolyploidization of nascent triticales, and great morphologic divergence might result from the genetic variations
Apart from directly synthesized hexaploid triticales by crossing tetraploid wheat with rye, secondary hexaploid triticales were developed by crossing an octoploid triticale and/or hexaploid wheat with a hexaploid triticale [14], and many hexaploid derivatives can spontaneously appear in octoploid triticales, which stem from partial elimination of wheat and rye chromosomes [15,16,17,18,19]
Summary
Polyploidy is a prominent process in plant speciation, and numerous important crop species are polyploid, most importantly allopolyploid [1,2,3]. Wittmack) were derived from Triticeae × rye (Secale cereale L.) in a variety of ploidy levels and genome constitutions, such as tetraploid triticale, hexaploid triticale and octoploid triticale [4,5,6,7]. Apart from directly synthesized hexaploid triticales by crossing tetraploid wheat with rye, secondary hexaploid triticales were developed by crossing an octoploid triticale and/or hexaploid wheat with a hexaploid triticale [14], and many hexaploid derivatives can spontaneously appear in octoploid triticales, which stem from partial elimination of wheat and rye chromosomes [15,16,17,18,19]. Hexaploid triticale could be either synthesized by crossing tetraploid wheat with rye, or developed by crossing hexaploid wheat with a hexaploid triticale or an octoploid triticale
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