Evidence for an atrial natriuretic peptide-like gene in plants

The presence of a gene found in the animal kingdom expressing a peptide hor monal system in plants has never been demonstrated. However, there is at le ast one potential hormonal system in plants (i.e., the atrial natriuretic p eptide-like hormonal system) based upon high-performance gel permeation chr omatography and radioimmunoaasay evidence, In plants, atrial natriuretic-li ke peptides enhance the flow of water up stems to leaves and flowers. The p resent investigation was designed to determine within plants the presence o f the atrial natriuretic peptide (ANP) gene as defined by Southern blot hyd ridization, indicating the presence of the ANP gene sequence, and by Northe rn blots assessing the ability of this gene to express ANP prohormone mRNA. Southern blots of English ivy (Hedra helix) genomic DNA revealed that the ANP gene sequence was present in its roots, stems, and leaves. Northern blo t analysis of total plant RNA isolated from leaves, roots, and stems of Hed ra helix revealed a single 0.85-kilobase prohormone ANP transcript in stems similar to that detected in rat heart. Semiquantitative analysis suggested that ANP gene expression was less in English ivy compared with that of rat heart atria but similar to the amount found in extra atrial rat tissues wh en corrected for total RNA when quantitated by 2D scanning. The demonstrati on of the ANP gene sequences and expression of the ANP-like gene in plants suggests that plants and animals may have evolved much more similarly than previously thought.