ORGANIZATION OF THE HISTONE H3 GENES IN SOYBEAN, BARLEY AND WHEAT

Several variants of the replacement histone H3 genes from soybean, bar ley and wheat have been cloned and sequenced. Analysis of segregating populations in barley and soybean, as well as analysis of clones isola ted from a soybean genomic library, suggested that these genes are dis persed throughout the genome. Several genes contain introns located in similar positions, but of different lengths and sequence. Comparison of mRNA levels in different tissues revealed that the intron-containin g and intronless genes have different expression patterns. The distrib ution of the introns in the histone H3 genes across several plant spec ies suggests that some of the introns might have been lost during the evolution of the gene family. Sequence divergence among introns and ge ne-flanking sequences in cloned gene variants allowed us to use them a s specific probes for localizing individual gene copies and analyzing the genomic distribution of these variants across a range of genotypes .