The endosperms of common cereals contain related poly A (+)RNA sequences.

mRNA has been isolated from the developing endosperms of four Triticeae species. Wheat endosperm mRNA has been used as a template to construct a bank of cDNA plasmid clones. More than 95% of these clones hybridized strongly to endosperm poly A(+)RNA but not to shoot poly A(+)RNA. (32)P-labelled mRNA from species related to wheat was used in filter hybridizations to detect inter-species sequence homologies. The wheat cDNA clones can be grouped into 4 classes: clones hybridizing to wheat RNA only, clones cross-hybridizing to barley endosperm poly A (+)RNA, clones cross-hybridizing to rye endosperm poly A(+) RNA, and clones showing homology to both barley and to rye RNA. Some of the sequence homology has been assigned to storage protein mRNA sequences.