MONO- AND BI-CISTRONIC CHIMERIC mRNAs IN ARABIDOPSIS AND RICE GENOMES

In contrast to prokaryotes, the proximity of genes in eukaryotic genomes has not previously been known to play any signiflcant role in their expression proflles. However, re- cently reported phenomena in human, mouse, yeast and a few plant species indicate such role: chimeric mRNAs and proteins produced via alternative transcription termination, splicing and translation of the Tail-to-Head (T2H) neighboring genes. To further verify this evidence at the genomic scale, we scanned the rice and Arabidopsis genomes for the presence of T2H gene pairs at a distance of less than 1000 bp. Our studies suggest that \non-stopping" transcription and alternative splicing of some of these T2H pairs may produce chimer transcripts. We ob- tained cDNA support for 100 Arabidopsis and 42 rice T2H pairs to be transcribed into chimeric mRNA(s). Analysis of 155 chimeric transcripts from both species revealed 71 mono-cistronic and 58 bi-cistronic mRNAs potentially encoding chimeric or separate proteins.