Abstract
Crested wheatgrass (Agropyron cristatum L. Gaertn., genome P), included in the Triticeae tribe (family Poaceae), is one of the most important grasses in temperate regions. It has been valued as a donor of important agronomic traits for wheat improvement, including tolerance to cold, drought, and high salinity, as well as resistance to leaf rust, stripe rust, and powdery mildew. For successful incorporation of beneficial alleles into wheat, it is essential that recombination between wheat and A. cristatum chromosomes occurs. In this work, we analysed chromosome associations during meiosis in wheat lines carrying chromosome introgressions from A. cristatum chromosomes 5P and 6P in the presence and absence of Ph1 locus using fluorescence in situ hybridisation. The results showed that the Ph1 locus does not affect chromosome associations between A. cristatum and wheat chromosomes because there were no interspecific chromosome associations; therefore, no recombination between chromosomes from wheat and Agropyron were observed in the absence of the Ph1 locus. The 5P and 6P A. cristatum chromosomes do not have a suppressor effect on the Ph1 locus. Wheat univalents in metaphase I suggest that Agropyron chromosomes might carry genes having a role in wheat homologous chromosome associations. Putative effect of the Agropyron genes on wheat chromosome associations does not interact with the Ph1 locus.
Highlights
Addition lines for chromosomes 5P and 6P in the Ph1 genetic background were obtained in the F3 progeny from crosses between A. cristatum additions for chromosomes 5P and 6P in wheat Chinese Spring (CS) with the CS Ph1 mutant, respectively [32]
We identified one ditelosomic A. cristatum introgression line for chromosome 5PS in the Ph1 genetic background, which only amplified the fragment for the COS108 marker located on the short arm of chromosome 5P, but not the one for the COS150 marker located on chromosome 5PL
These results showed that interspecific chromosome associations between A. cristatum and wheat chromosomes are not promoted in the absence of the Ph1 locus, suggesting that pairing earlier in meiosis
Summary
A. cristatum is a perennial species of economic importance that is widely cultivated in North America as an excellent source of forage, and included in the diets of beef and dairy cattle worldwide [2]. This species shows tolerance to cold, drought, and high salinity, and is one of the most important grasses in temperate regions [3,4]. It has been valued for stabilization of heavy metal-contaminated soils [5,6] and watershed management [7]. Hybrids and fertile amphiploids between Triticum and A. cristatum have been successfully obtained [15,16,17,18] with the aim to develop wheat-A. cristatum introgressions [8,14,19]
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