Cloned maize genomic sequences recovered by homology to meiosis-specific cDNA clones from Lilium or their maize small heat shock gene cognate

A previous report (see MNL 60:71, 1986) described the recovery of a maize genomic DNA clone through its sequence homology to expressed meiotic prophase repeat (EMPR) cDNA clones from Lilium, a clone encoding a product with regions of strong amino acid similarities to small heat shock protein of soybean. Further studies have shown that this clone reanneals with high fidelity to an mRNA induced at least 50-fold in heat-shocked maize somatic tissue. A larger genomic clone containing the entire structural gene plus flanking regions has now been recovered. Collaborative sequencing studies (Dietrich, Bouchard, DeSilva, and Sinibaldi, J. Cell Biol. 105:245a, 1987) have now been performed on an extensive segment of this clone containing the gene and associated regulatory regions, and it appears by several criteria to be a genuine maize small hsp gene.

Maize cognate genomic clones have been recovered through their reassociation homology to either lily EMPR clones or the maize small hsp clone. They appear to fall into two classes: those containing inserts which reassociate with both the lily meiotic and maize small hsp gene probes, and those containing inserts reassociating only with the maize small hsp gene probe. Plasmid subclones for examples of each have been produced and are being characterized. Interestingly, RNAs complementary to these examples of both classes of cognate sequences are present in heat shocked and normal maize somatic tissues at comparable levels. Additional studies are underway to further examine the relationships and expression patterns of this complex group of related sequences.

Robert A. Bouchard


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