(b, Neu-Ulm, Germany, 25 April 1883; d. Munich, Germany, 8 July 1960)
Renner was typical of late-nineteenth- and early-twentieth-century German biologists. He was greatly respected by researchers in plant physiology and plant cytogenetics, but almost unknown to other scientists. He never wrote a book or a scientific monograph that summed up his research discoveries. The topic to which he made his major contributions, the cytogenetics of the evening primrose (Oenothera), is removed from the mainstream of cytogenetic research. Nevertheless, his discoveries help to explain both the nature of the “mutations” upon which Hugo de Vries built his “mutation theory” of evolution and the chromosomal mechanism that permits an organism to retain a high degree of genetic heterozygosity and still produce constant, true-breeding descendants.
In his private life Renner had broad interests. He was thoroughly familiar with ancient literary classics, which he read in the original Greek. A dedicated naturalist, he knew both the flora of his native Germany and tropical floras, although floristics was more an avocation than a serious object of research for him.
The son of Ludwig Renner, a teacher, and of Marie Kopf Renner, Renner spent his entire life in academic surroundings. After attending the gymnasium in Ulm, he studied at the University of Munich, from which he graduated in 1905. The following year he spent one semester at the University of Leipzig, where, under the direction of the plant physiologist Wilhelm Pfeffer, he acquired the first of his two major research interests, water relations in plants. The botanist Karl Goebel called him back to Munich to be his first assistant. Except for service during World War I in the German army, after which he worked as a bacteriologist at a hospital in Ulm, Renner remained at Munich until 1920. At first he combined research on plant morphology with that on water relations of growing plants, but in 1913, when he was promoted to assistant professor of plant physiology and pharmacognosy, he engaged in a scientific discussion that launched his career in plant genetics, to which he made major contributions.
Richard Goldschmidt, then a Privatdozent in zoology at Munich, told Renner about an apparent example of patroclinous inheritance (derived or inherited from the male parent) in the evening primrose (Oenothera). When Goldschmidt presented his explanation to Renner—that the plants in question contained only genes derived from the pollen of the male parent—Renner, highly skeptical, decided to test the hypothesis. He quickly obtained cytological evidence to show that Goldschmidt was wrong.
Continuing his research on Oenothera, Renner had shown by 1920 that in the species upon which de Vries had based his mutation theory of evolution, the independent assortment of gene differences predicted by Mendel’s second law of heredity is largely or completely absent. Most plants produce two, and only two, kinds of egg or pollen nuclei, as if all of the genes were linked on a single chromosome. Furthermore, a combination of lethal genes causes embryos and seeds to die unless they are derived from pollen and egg that contain different sets of genes. As a result, many strains that have uniparental reproduction, via self-pollination, nevertheless are highly heterozygous genetically. The sets of genes that are transmitted intact, generation after generation, became known as Renner complexes.
These startling results, plus his solid research on water relations, earned Renner in 1920 the position of professor of botany and director of the botanical garden at Jena, where he remained for twenty-eight years.
In 1920 Renner married Johanna Unterbirker. They had a daughter, Hildegard, who became a physician, and a son, Erwin, who died in a climbing accident.
During the next decade, the American cytologist Ralph E. Cleland showed that Renner’s unexpected results could be explained on the basis of the unusual behavior of the chromosomes during meiosis. Instead of forming seven pairs, the fourteen chromosomes become united into either a single ring or a ring of twelve and a pair. Normal eggs and pollen are formed only when chromosomes that occupy alternate positions in the ring—1, 3, 5, 7, 9, 11, 13 and/or 2, 4, 6, 8, 10, 12, 14—pass to the same pole of the spindle and are included in the same gamete. These sets of chromosomes contain the genes that make up Renner complexes.
Unusual deviation from this behavior can cause the complex to be broken up, giving rise to aberrant progeny of the sort that de Vries called “mutations.” Such “mutations” do not involve any change in the genes themselves, but only in their pattern of distribution. When Renner and Cleland realized that their discoveries complemented each other, Cleland spent a year (1927–1928) in Renner’s laboratory, and with the German cytologist Friedrich Oehlkers he completed the synthesis of genetic and cytological information.
Continuing his research on Oenothera hybrids, Renner found reciprocal differences in inheritance of chlorophyll pigmentation that could best be explained on the hypothesis that cellular organelles such as chloroplasts carry genetic information. Analyzing the behavior of a mutant, cruciata, that gives rise to abnormally shaped petals, he obtained evidence of gene conversion. In these respects his research on developmental genetics anticipated modern trends.
A staunch Catholic, Renner could not accept Hitler’s regime, but maintained his research institute at Jena as well as he could. The institute was completely destroyed by bombing in the spring of 1945 (he barely escaped alive). He fled from Jena in 1948 and returned to Munich; he restored the buildings before he retired in 1953. He continued to work in the botany department at Munich until his death.
Renner received many honors. Among his honorary degrees were those awarded by the universities of Jena, Erlangen, and Freiburg. He was a member of German academies of sciences—Berlin, Leipzig, Göttingen, Halle, and Munich—as well as foreign member of the Genetical Society of Great Britain, the Royal Society, the Botanical Society of America, the American Academy of Arts and Sciences, the American Philosophical Society, and the U.S. National Academy of Sciences. In 1952 he was made knight of the Order pour le Mérite, the oldest, highest, and rarest award given in Germany.
Renner was an original, dynamic, and outspoken scientist. He was equally critical of Nazism and the communism that followed it in East Germany. Nevertheless, his scientific integrity and warm personality won the approval of all who knew him.
I. Original Works. “Wasserversorgung der Pflanzen,” in Handwörterbuch der Naturwissenschaften, 10 (1915), 538–557; “Versuche über die gametrische Konstitution der Oenotheren,” in Zeitschrift für Vererbungslehre, 18 (1917), 121–294; Artbastarde bei Pflanzen, vol. II , pt. A, Lieferung 7 of Erwin Baur and Max Hartmann, eds., Handbuch der Vererbungswissenschaft (Berlin, 1929); “Zur Genetik und Cytologie der Oenothera chicaginensis und ihre Abkömmlinge,” in Zeitschrift für Vererbungslehre, 66 (1933), 275–318, written with Ralph E. Cleland; “Zur Kenntnis der Letalfaktoren und des Kopplungswechsels bei Oenotheren,” in Flora, 127 (1934), 212–250; “Zur Kenntnis der nichtmendelnden Buntheit der Laubblätter,” ibid., 130 (1935–1936), 218–290; “Über Oenothera atrovirens Sh. et Bartl. und über somatische Konversion im Erbgang des Cruciata-Merkmals der Oenotheren,” in Zeitschrift für Vererbungslehre, 74 (1938), 91–124; “Über die Entstehung der homozygotischen Formen aus komplexheterozygotischen Oenotheren,” in Flora, 135 (1941), 201–238; “Über das Crossing-over bei Oenothera,” ibid., 136 (1942), 117–214; “Über den Erbgang des Cruciata-Merkmals der Oenotheren, V ,” in Planta, 48 (1957), 343–392; and “Somatic Conversion in the Heredity of the Cruciata Character in Oenothera,” in Heredity, 13 (1959), 283–288.
II. Secondary Literature. R.E. Cleland, “Otto Renner,” in Genetics, 53 (1966), 1–6; and C.D. Darlington, “Otto Renner,” in Biographical Memoirs of Fellows of the Royal Society, 7 (1961), 207–220, with complete bibliography.
G. L. Stebbins