Molecular analysis of Kr1 gene responsible for crossability of common wheat with alien species

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Common wheat is one of the most important crops as well as rice and maize. For the purpose of improvement of wheat cultivars, alien genes of the genus rye and Aegilops have been incorporated into common wheat, and many cultivars having cold resistance, desease and insect resistance, and high quality proteins have been produced. However, in the case of introduction of alien genes, hybridization between wheat and alien species have been a big problem. Crossability of common wheat with rye have been clarified to be located on the chromosomes of homoelogous group 5 of common wheat. The effects of Kr genes are expressed on the stigma and ovule, and inhibit the penetration and elongation of pollen tubes. In the present research, on the purpose of clarifying the mechanism of crossability, we tried to isolate the DNA fragments which are correspond to the Kr1 gene, and clone the fragments and identify the nucleotide sequences. Materials used are 20 recombinant inbred lines produces from the cro … More ssing between Chinese Spring wheat (kr1), which has high crossability with rye, and its 5B chromosome substitution line derived from cv.Mara (Kr1) which has low crossability. These lines were classified according to their crossability with rye. In the flowering period, pistils of wheat lines were collected and classified in to two groups and their bulked mRNAs were isolated. Through reverse transcription method, cDNAs were synthesized and polymorphism were detected by DD-RAPD and DD-AFLP method. The results from DD-RAPD has a problem on the repeatability and not reliable. In the case of DD-AFLP, after the analysis using 1723 primer pairs, 62 specific cDNA fragments for Kr1 lines were identified. Among them, 31 fragments were excised from the gel, and 24 clones were obtained. Nucleotide sequences of them showed that they were homologous to the genes for the protein of two factors control system of Arabidopsis thaliana and the precursor of cystein protenase. In the future, northern analysis will be necessary to examine the tissue specific gene expression in pistils of common wheat. Less