Characterization of a partial wheat–Thinopyrum intermedium amphiploid and its reaction to fungal diseases of wheat

摘要

The ongoing improvement of wheat cultivars is dependent on a continuous supply of genetic variability. Thinopyrum intermedium (Host) Barkworth & D.R. Dewey [syn. Agropyron intermedium (Host) Beauvoir and Elytrigia intermedia (Host) Nevski] (2n= 6x= 42) carries many useful agronomic traits and constitutes a tertiary gene pool for wheat improvement. Th. intermedium is a segmental autoallo-hexaploid, and the determination of its genomic composition has been of interest for a considerable time. However, due to the impact of pairing regulation gene(s) and chromosome pairing complexities as well as the high levels of polymorphism in Giemsa banded patterns within the species, no definite conclusions have been made based on traditional cytogenetic techniques, such as meiotic chromosome pairing and C-banding analysis (Chen et al. 1998).The transfer of alien genes into wheat (Triticum aestivum L., 2n= 6x= 42, ABD) via wide hybridization makes possible to increase the resistance to biotic and abiotic stress and improvement of quality. In wheat breeding programs, the production of amphiploids or partial amphiploids between wheat and relative species is an important intermediate step for such a gene transfer, because they allow the reliable analysis of the effects of alien genes in the genetic background of wheat and their fertility allows gene transfer even when an F1 hybrid is almost completely sterile (Jiang et al. 1994; Ellneskog-Staam and Merker 2002). The wild relatives, Th. intermedium (2n= 6x= 42, JJsS), has a wealth of genetic variation for the improvement of resistance to fungal and viral diseases in wheat (Li et al. 2008; Li and Wang 2009). To date, several wheat–Th. intermedium amphiploids, Otrastsyuskaya (OT), TAF46, Zhong1 to Zhong5, 78829, TAI7044 and TE-3, have been obtained (Chang et al. 2003; Chen 2005; Fedak and Han 2005; Yang et al. 2006). Some of them have been widely used for attempted introgressions of useful traits into wheat, including resistance to viral diseases (Larkin et al. 1995; Friebe et al. 1996; Chen et al. 2003; Li et al. 2008; Li and Wang 2009). However, partial amphiploid still do not cover the entire genome of Th. intermedium, due to the complexity of the genomic composition of the alien parent. The exploitation of a new wheat–Th. intermedium partial amphiploid type still remains necessary for understanding the genetic relationships of the S and J or Js genomes of Thinopyrum with those of wheat, and for incorporating disease-resistance genes from Th. intermedium into wheat. TAI8335 is a Th. intermedium-derived partial amphiploid that was recently developed in our laboratory. In this study, we attempted to determine the chromosome composition and genomic origins of the alien chromosomes of TAI8335 by genomic in situ hybridization (GISH) and to evaluate its potential as a novel source for resistance to fungal pathogens.