By HAROLD M. SCHMECK Jr.
Published: January 19, 1988
NO one can get blood from a turnip, but it might prove possible to find the blood substance hemoglobin in one.
In a new report in the journal Nature, scientists say they suspect that all plants have the genes needed to produce hemoglobin.
In animals and humans, hemoglobin is the vital substance that carries blood to all tissues of the body. It has long been known that plant equivalents of hemoglobin exist in the root nodules of many plants that can incorporate nitrogen from the air into useful compounds. The nodules are the abode of certain bacteria that are crucial to the nitrogen fixing process. It has been assumed that the hemoglobin in root nodules is used to transport oxygen needed by the bacteria, among other things.
But now scientists report evidence of hemoglobin’s presence in other plants that do not form root nodules, leading the researchers to the view that hemoglobin may be as ubiquitous in plants as it is in animals. Difficult to Find in Leaves
”Our data suggest that all plants have hemoglobin genes and imply that hemoglobin has a function, presumably associated with oxygen transport, in cells of normal roots,” the report said. The scientists used techniques of molecular biology to search for hemoglobin in non-nodule forming plant species.
They found genes for the substance in roots of Trema tomentosa, a tree that grows in tropical and subtropical areas and also found related evidence suggesting that such genes may be universal although often difficult to detect. The evidence indicated that the substance may be common to roots but difficult to find in leaves.
Close analysis of the gene in Trema suggests that it is not just a piece of useless genetic debris, but is functional and that the hemoglobin that is the product of the gene could play a role in oxygen transport.
The report was by plant physiologists of the Division of Plant Industry in Canberra, Australia, and by scientists in Paris and West Germany. The scientists suggest that hemoglobin has come down through evolution from a common ancestor of plants and animals. The researchers said genes for plant hemoglobin in roots may be ubiquitous and may have evolved differently in various species that have such genes in their root nodules. The new finding would appear to be futher evidence that all forms of life are blood kin under the skin -and in the roots.