Cytological And Molecular Characterization Of A Set Of Wheat-A. Cristatum Disomic Addition Lines

Morphological, cytological, molecular methods and pathological screening were employed to analyze the cytological stability, agronomic characters and homoeologous relationship between bread wheat and wheatgrass (Agropyron cristaum) (2n=4x=28) chromosome of 20 wheat-A. cristaum chromosome disomic addition lines.Among the 20 addition lines analyzed, great variations of cytological stabilities existed. Plants with chromosome constitution of 2n=44 varied greatly between open-pollinated progenies of 10 wheat-A. cristaum addition lines, ranging from 33.3% to 100%, with average 74.78%. In the remaining 10 addition lines, no plants with 2n=44 were observed while the plants with 2n=42 predominated. However, GISH analysis for progenies with 2n=42 of 4 disomic addition lines showed that one translocation line and one substitution line between A. cristatum and wheat chromosomes were recovered. It is suggested that translocation or substitution between A. cristatum and wheat chromosomes occurred readily. Therefore, strengthening detection for the alien chromatin in the progenies of disomic addition lines can be helpful for the recovery of translocation or substitution lines with desirable genes from A. cristatum genome.According to the similarities of morphological and agronomic characters, ten disomic addition lines can be divided into five groups, with which each group has its typical characteristics. For the progenies with chromosomal constitution of 2n=42, they displayed thicker stems, longer spikes, taller height and longer internode length underneath spike than those of the counterpart plants with 2n=44. Obvious difference of seed color was observed on the two types of plants with different chromosomal constitutions.SSR results showed that SSR primer sets from wheat (Triticum aestivum) and Aegilops tauschii, can amplified A.cristatum chromosome-specific bands from A. cristaum genome. Among 101 polymorphic primers between Fukuho and Z559, which are the wheat and A. cristatum parents respectively, 24 primer sets can amplify wheatgrass-specific bands from the wheat-A. cristatum disomic addition lines. With one SSR marker from each homoelogous group, the homoeologous relationship between wheat and A. cristatum chromosomes can be established readily. However, with the increasing of SSR markers, such homoeologous relationship displayed complicated tendency. This may imply structurally intricate changes occurring during the evolution of P genome in A. cristatum.From the 24 lines derived from progenies of wheat and A. cristatum cross, several lines were identified as resistant lines to either wheat powdery mildew or yellow rust pathogen isolates. Three and four disomic addition lines displayed resistant to powdery mildew and yellow rust, respectively. Four derivatives from two addition lines were screened as resistant lines to the both pathogens above-mentioned.Cytological analysis combined with molecular analysis on the lines of II-21-2 and II-21-6,...