Construction and Screening of Indica Rice Genomic Library for Sequences Homologous to Sorghum Storage Protein Kafirin

Rice DNA of about 50 kb was isolated, partially digested with EcoRI and fractionated on 10–40% sucrose density gradient to obtain DNA fragments in the size range of 10–20 kb. Bacteriophage vector Charon 4A was also digested with EcoRI and two arms were purified by sucrose density gradient centrifugation. The purified Charon 4A arms and size fractionated rice DNA were ligated and used for in vitro packaging. The development of in vitro packaging extract made it possible to construct a genomic library which represented 7–8 rice genomes, considering the haploid DNA content of rice as 1 pg. This library was screened using a heterologous kafirin cDNA probe from Sorghum bicolor and three clones homologous to kafirin, were identified.