Construction of Chloroplast Genomic Library of Amaranthus cruentus R104 and Cloning of the Gene for the Large Subunit of Ribulose-1, 5-disphosphate Carboxylase/Oxygenase

Grain amaranth is an annual food and forage crop and C4-plant with characteristics of rich nutrients, high photosynthesis efficiency and strong stress-resistance. Chloroplast DNA (ctDNA) was prepared from Amaranthus cruentus R104. The ctDNA was digested with restriction enzymes Barn HⅠ, EcoRⅠ, BgⅢ, PstⅠ and SaⅡ, and the fragments thus obtained were electrophoresed in 0.7% agarose gel. The Length of the doublestranded ctDNA was measured to be 140 kb or so. BamHI-digested fragments of R104 ctDNA were inserted into pBR322 and a chloroplast genomic library has been constructed. The recombinant clone containing rbcL gene has been identified and selected out from the library. The restriction analysis of the clone showed that the rbcL gene of A. cruentus R104 has the structure similar to that of C4-plant corn. Moreover the reason of unsuccessful cloning of 5.9 kb BamHI fragment containing psbA gene is discussed.