Abstract: The plant materials used were the leaves of Aegilops squarrosa L., Triticum aestivum L. and a nucleo-cytoplasmic hybrid wheat which was obtained by crossing T. aestivum ( ♂ )with A. squarrosa( ♀ )and backcrossing 10 generations with T. aestivum as the paternal parent. The carboxylasc and oxygenase activities of these materials were assayed. At the same time, a λgtl0 eDNA library of 5.5 x 105 pfu was constructed with poly (A)RNA from the leaves of A. squarrosa seedlings. This library was screened with a partial fragment of rice rbeS, and a eDNA clone pRAS1 that includes A. squarrosa rbcS was obtained. Nucleotide sequencing indicated that the full length of this eDNA was 815 bp. Con'son of small subunit of ribulosc-l,5-bisphosphate carboxulase/oxygenase (rubisco) from A. squarrosa with that from T. aestivum and their nucleo-cytoplasmic hybrid wheat revealed that the amino acid residues at positions 56, 84, 98 and 117 in the small subunit might play important roles in regulating the activities of mbisco.

Key words: Aegilops squarrosa, Nueleo-cytoplasmic hybrid wheat, Small subunit of ribulose-1, 5-bisphosphate earboxylasc/oxogenase