Cloning and mapping of the chloroplast DNA sequences for two messenger RNAs from mustard (Sinapis alba L.).

Restriction fragments of chloroplast (cp)DNA from mustard leaves were cloned in E. coli using pBR 322 as the vehicle. Cloned fragments containing the structural sequences for two polypeptides of 56,000 and 35,000 daltons were selected by a mRNA hybridization-translation procedure. The cloned mustard genes are structurally related to chloroplast genes from maize. They hybridize to the maize mRNAs for the large subunit of ribulosebisphosphate carboxylase and for the 34,500 dalton precursor to a membrane protein. The coding sequence on mustard cpDNA for the 56,000 dalton polypeptide is colinear with a 1,500 base pair transcript, and the sequence for the 35,000 dalton polypeptide is colinear with a 1,220 base pair transcript.