Development and application of specific FISH probes for karyotyping Psathyrostachys huashanica chromosomes

Abstract

AbstractBackgroundPsathyrostachys huashanicaKeng has long been used as a genetic resource for improving wheat cultivar because of its genes mediating the resistance to various diseases (stripe rust, leaf rust, take-all, and powdery mildew) as well as its desirable agronomic traits. However, a high-resolution fluorescencein situhybridization (FISH) karyotype ofP. huashanicaremains unavailable.ResultsTo develop chromosome-specific FISH markers forP. huashanica, repetitive sequences, including pSc119.2, pTa535, pTa713, pAs1, (AAC)5, (CTT)12, pSc200, pTa71A-2, and Oligo-44 were used for a FISH analysis. The results indicated that the combination of pSc200, pTa71A-2 and Oligo-44 probes can clearly identify all Ns genomic chromosomes in the twoP. huashanicagermplasms. The homoeologous relationships between individualP. huashanicachromosomes and common wheat chromosomes were clarified by FISH painting. Marker validation analyses revealed that the combination of pSc200, pTa71A-2, and Oligo-44 for a FISH analysis can distinguish theP. huashanicaNs-genome chromosomes from wheat chromosomes, as well as all chromosomes (except 4Ns) from the chromosomes of diploid wheat relatives carrying St, E, V, I, P and R genomes. Additionally, the probes were applicable for discriminating between theP. huashanicaNs-genome chromosomes in all homologous groups and the corresponding chromosomes inPsathyrostachys junceaand mostLeymusspecies containing the Ns genome. Furthermore, six wheat–P. huashanicachromosome addition lines (i.e., 2Ns, 3Ns, 4Ns, 7Ns chromosomes and chromosomal segments) were characterized using the newly developed FISH markers. Thus, these probes can rapidly and precisely detectP. huashanicaalien chromosomes in the wheat background.ConclusionsThe FISH karyotype established in this study lays a solid foundation for the efficient identification ofP. huashanicachromosomes in wheat genetic improvement programs.