International Prize for Biology
2026 Prize Recipient
The Committee on the International Prize for Biology
awards the 2026 Prize in the field of "Biology of Symbiosis (interspecific interactions)” to
Dr. Sharon Rugel Long
Steere-Pfizer Professor of Biological Sciences – Stanford University, USA
awards the 2026 Prize in the field of "Biology of Symbiosis (interspecific interactions)” to
Dr. Sharon Rugel Long
Steere-Pfizer Professor of Biological Sciences – Stanford University, USA
On July 10, the Committee on the International Prize for Biology (chaired by Dr. FUJIYOSHI Yoshinori, Specially Appointed Professor, Institute of Science Tokyo) decided to award the 42nd (2026) International Prize for Biology to Dr. Sharon Rugel Long, Steere-Pfizer Professor of Biological Sciences, Department of Biology – Stanford University, USA.This year’s Prize is awarded in the field of "Biology of Symbiosis (interspecific interactions). "
Dr. Sharon Rugel Long
YEAR OF BIRTH: 1951
NATIONALITY: United States of America
PRESENT POSITION: Steere-Pfizer Professor of Biological Sciences, Department of Biology – Stanford University
YEAR OF BIRTH: 1951
NATIONALITY: United States of America
PRESENT POSITION: Steere-Pfizer Professor of Biological Sciences, Department of Biology – Stanford University
1973 Graduated from California Institute of Technology (B.S. with Honors)
1979 Graduated from Yale University (Ph.D. in Cell and Developmental Biology)
1979‒1981 Postdoctoral Fellow, Harvard University
1982‒1992 Assistant Professor/Associate Professor, Department of Biology, Stanford University
1992‒present Professor, Department of Biology, Stanford University
1994‒2001 Investigator, Howard Hughes Medical Institute
2000-present Wm.C.Steere, Jr.-Pfizer, Inc. Professorship in Biological Sciences, Stanford University
2001‒2007 Dean, School of Humanities and Sciences, Stanford University
2018‒present Co-founder and Scientific Advisory Board Chair, ExoPolymer, Inc.
1979 Graduated from Yale University (Ph.D. in Cell and Developmental Biology)
1979‒1981 Postdoctoral Fellow, Harvard University
1982‒1992 Assistant Professor/Associate Professor, Department of Biology, Stanford University
1992‒present Professor, Department of Biology, Stanford University
1994‒2001 Investigator, Howard Hughes Medical Institute
2000-present Wm.C.Steere, Jr.-Pfizer, Inc. Professorship in Biological Sciences, Stanford University
2001‒2007 Dean, School of Humanities and Sciences, Stanford University
2018‒present Co-founder and Scientific Advisory Board Chair, ExoPolymer, Inc.
1984 NSF Presidential Young Investigator Award
1988, 1992 Dean’s Award for Teaching Excellence, Stanford University
1992‒1997 MacArthur Fellowship, Ellen MacArthur Foundation
1993‒present Member, National Academy of Sciences
1994 Fellow, American Academy of Arts and Sciences
1997‒2000 Bing Teaching Fellow, Stanford University
1998 INRA George Morel Memorial Fellowship
1998 Distinguished Alumni Award, California Institute of Technology
1999 Fellow, Association for Women in Science
2000 Fellow, American Philosophical Society
2002 Wilbur Cross Medal, Yale University
2007 Fellow, American Society of Plant Biologists
2016 Lifetime Research Award, International Society for Molecular Plant-Microbe Interactions
2019 Selman A. Waksman Award in Microbiology, National Academy of Sciences
1988, 1992 Dean’s Award for Teaching Excellence, Stanford University
1992‒1997 MacArthur Fellowship, Ellen MacArthur Foundation
1993‒present Member, National Academy of Sciences
1994 Fellow, American Academy of Arts and Sciences
1997‒2000 Bing Teaching Fellow, Stanford University
1998 INRA George Morel Memorial Fellowship
1998 Distinguished Alumni Award, California Institute of Technology
1999 Fellow, Association for Women in Science
2000 Fellow, American Philosophical Society
2002 Wilbur Cross Medal, Yale University
2007 Fellow, American Society of Plant Biologists
2016 Lifetime Research Award, International Society for Molecular Plant-Microbe Interactions
2019 Selman A. Waksman Award in Microbiology, National Academy of Sciences
In the early 1980s, root nodule symbiosis between rhizobia and leguminous plants was known to exhibit strict host specificity, and it had been suggested that its establishment involved a multistage process of genetic regulation; however, the underlying molecular mechanisms remained unclear. Through molecular genetics, biochemical, and cell biological analyses of both rhizobia and host plants, Dr. Sharon Rugel Long focused on the “molecular dialogue” conveyed through chemical signals exchanged between the two and made major contributions to elucidating the mechanisms underlying host specificity and the subsequent molecular mechanisms of root nodule symbiosis.
In 1982, Dr. Long identified the genetic region in rhizobia required for the establishment of root nodule symbiosis and was the first in the world to report the nod genes located within this region (Ref. 1). This discovery led to the subsequent identification, by her lab and others, of both the common nod genes conserved among rhizobial species and also strain-specific nod genes, sparking a fierce race among researchers to elucidate their functions.
In 1985–1986, Dr. Long demonstrated that luteolin, a flavonoid secreted by alfalfa roots, induces the expression of the nod genes in alfalfa rhizobia, Sinorhizobium meliloti (Refs. 2, 3). This discovery demonstrated the existence of interspecies communication mediated by chemical signals from the host plant to the rhizobium and revealed that host plants actively regulate symbiosis with rhizobia through flavonoid signaling.
Subsequent studies led by Dr. Long demonstrated that the enzymes encoded by the nod genes induced by flavonoids synthesize the Nod factor (a rhizobial signaling molecule comprising a chitin-oligosaccharide backbone). In 1990, Dr. Long proposed that the products of the nodP and nodQ genes, which are involved in host specificity in Sinorhizobium meliloti, chemically modify the chitin-oligosaccharide backbone of the Nod factor to generate host-specific Nod factors (Ref. 4). The structural variation in Nod factors correlated with the observation that the Nod factor induces morphological changes, including deformation of root hairs (epidermal cells of roots protruding like hairs) and division of cortical cells that give rise to root nodules, as well as the expression of symbiosis-related genes, but only in compatible host plants.
In 1996, Dr. Long discovered that only host-specific Nod factors induce calcium spiking in the root hair cells of host plants (Ref. 7). She further demonstrated that calcium spiking is absent in certain symbiosis-defective mutant host plants, establishing that calcium spiking is required for the establishment of symbiosis and that the genes responsible for these mutant phenotypes are involved in the induction of calcium spiking. These findings indicated the existence of chemical communication from rhizobia to host plants and showed that this chemical signal is transduced into an intracellular signal in the host through calcium spiking. This discovery became one of the greatest turning points in the history of root nodule symbiosis research. Thereafter, genes regulating symbiosis in host plants came to be classified according to their roles in calcium spiking—either as genes involved in its induction or as downstream components of the calcium signaling pathway—and their identification and functional characterization advanced rapidly.
In addition to the achievements described above, from the late 1990s onward Dr. Long’s research group accelerated molecular genetic studies of host plants by developing and making publicly available an expressed gene database for the host plant Medicago truncatula (Ref. 8). In 2001, the group also decoded the complete genome sequence of Sinorhizobium meliloti (Refs. 10, 11). Building on these genomic resources, Dr. Long developed the world’s first GeneChip (a high-density microarray platform for gene expression analysis) incorporating genes from both the host plant and the rhizobium. Analyses using this platform led her to propose that root nodule symbiosis is a developmental program involving extensive reprogramming of gene expression in both symbiotic partners (Ref. 15). Dr. Long subsequently combined the GeneChip platform with symbiosis-defective host plant mutants to identify genes whose DNA was deleted in these mutants, leading to the discovery of the DMI3 gene, which is essential for root nodule symbiosis (Ref. 14). DMI3 encodes a calcium/calmodulin-dependent protein kinase that is activated by calcium and calmodulin (a calcium-binding protein) and phosphorylates target proteins. Subsequent studies established that DMI3, activated by calcium spiking, functions as a central regulator that activates the downstream signaling pathway required for the establishment of symbiosis.
Root hair cells deformed through rhizobial infection form an infection thread, through which the rhizobia enter and establish residence inside the developing root nodule. In the 2010s, Dr. Long’s research group showed that plasma membrane domains containing Nod factor receptors are dispersed across the surface of root hair cells in the absence of rhizobial infection. On the other hand, upon rhizobial infection, these membrane domains reorganize toward the future site of infection thread formation, initiating its formation and thereby promoting the rhizobial infection (Ref. 18).
Dr. Long’s research elucidated the initial stages of the process underlying the establishment of root nodule symbiosis. Rhizobia perceive flavonoids released by the host plant and respond by synthesizing host-specific Nod factors, which initiate symbiosis by inducing calcium spiking in the host. In host cells that have received Nod factors, the resulting calcium spiking is transmitted through DMI3 to downstream pathways that regulate symbiosis. In root hair cells, Nod factor-dependent reorganization of plasma membrane domains gives rise to infection thread formation, thereby promoting rhizobial infection. These dynamic mechanisms underlying root nodule symbiosis are now described in numerous textbooks and review articles as the fundamental principles of its establishment.
Dr. Long elucidated the mechanism by which the bidirectional “molecular dialogue” between host plants and rhizobia, mediated by flavonoids and Nod factors, governs the establishment of host-specific root nodule symbiosis. Furthermore, through her discovery of calcium spiking, she revealed a fundamental principle by which chemical communication between different organisms is transduced into intracellular signal transduction, thereby laying the theoretical foundation for root nodule symbiosis research. Her findings have driven progress in the field for several decades and continue to shape the direction of research on plant-microbe interactions today.
In 1982, Dr. Long identified the genetic region in rhizobia required for the establishment of root nodule symbiosis and was the first in the world to report the nod genes located within this region (Ref. 1). This discovery led to the subsequent identification, by her lab and others, of both the common nod genes conserved among rhizobial species and also strain-specific nod genes, sparking a fierce race among researchers to elucidate their functions.
In 1985–1986, Dr. Long demonstrated that luteolin, a flavonoid secreted by alfalfa roots, induces the expression of the nod genes in alfalfa rhizobia, Sinorhizobium meliloti (Refs. 2, 3). This discovery demonstrated the existence of interspecies communication mediated by chemical signals from the host plant to the rhizobium and revealed that host plants actively regulate symbiosis with rhizobia through flavonoid signaling.
Subsequent studies led by Dr. Long demonstrated that the enzymes encoded by the nod genes induced by flavonoids synthesize the Nod factor (a rhizobial signaling molecule comprising a chitin-oligosaccharide backbone). In 1990, Dr. Long proposed that the products of the nodP and nodQ genes, which are involved in host specificity in Sinorhizobium meliloti, chemically modify the chitin-oligosaccharide backbone of the Nod factor to generate host-specific Nod factors (Ref. 4). The structural variation in Nod factors correlated with the observation that the Nod factor induces morphological changes, including deformation of root hairs (epidermal cells of roots protruding like hairs) and division of cortical cells that give rise to root nodules, as well as the expression of symbiosis-related genes, but only in compatible host plants.
In 1996, Dr. Long discovered that only host-specific Nod factors induce calcium spiking in the root hair cells of host plants (Ref. 7). She further demonstrated that calcium spiking is absent in certain symbiosis-defective mutant host plants, establishing that calcium spiking is required for the establishment of symbiosis and that the genes responsible for these mutant phenotypes are involved in the induction of calcium spiking. These findings indicated the existence of chemical communication from rhizobia to host plants and showed that this chemical signal is transduced into an intracellular signal in the host through calcium spiking. This discovery became one of the greatest turning points in the history of root nodule symbiosis research. Thereafter, genes regulating symbiosis in host plants came to be classified according to their roles in calcium spiking—either as genes involved in its induction or as downstream components of the calcium signaling pathway—and their identification and functional characterization advanced rapidly.
In addition to the achievements described above, from the late 1990s onward Dr. Long’s research group accelerated molecular genetic studies of host plants by developing and making publicly available an expressed gene database for the host plant Medicago truncatula (Ref. 8). In 2001, the group also decoded the complete genome sequence of Sinorhizobium meliloti (Refs. 10, 11). Building on these genomic resources, Dr. Long developed the world’s first GeneChip (a high-density microarray platform for gene expression analysis) incorporating genes from both the host plant and the rhizobium. Analyses using this platform led her to propose that root nodule symbiosis is a developmental program involving extensive reprogramming of gene expression in both symbiotic partners (Ref. 15). Dr. Long subsequently combined the GeneChip platform with symbiosis-defective host plant mutants to identify genes whose DNA was deleted in these mutants, leading to the discovery of the DMI3 gene, which is essential for root nodule symbiosis (Ref. 14). DMI3 encodes a calcium/calmodulin-dependent protein kinase that is activated by calcium and calmodulin (a calcium-binding protein) and phosphorylates target proteins. Subsequent studies established that DMI3, activated by calcium spiking, functions as a central regulator that activates the downstream signaling pathway required for the establishment of symbiosis.
Root hair cells deformed through rhizobial infection form an infection thread, through which the rhizobia enter and establish residence inside the developing root nodule. In the 2010s, Dr. Long’s research group showed that plasma membrane domains containing Nod factor receptors are dispersed across the surface of root hair cells in the absence of rhizobial infection. On the other hand, upon rhizobial infection, these membrane domains reorganize toward the future site of infection thread formation, initiating its formation and thereby promoting the rhizobial infection (Ref. 18).
Dr. Long’s research elucidated the initial stages of the process underlying the establishment of root nodule symbiosis. Rhizobia perceive flavonoids released by the host plant and respond by synthesizing host-specific Nod factors, which initiate symbiosis by inducing calcium spiking in the host. In host cells that have received Nod factors, the resulting calcium spiking is transmitted through DMI3 to downstream pathways that regulate symbiosis. In root hair cells, Nod factor-dependent reorganization of plasma membrane domains gives rise to infection thread formation, thereby promoting rhizobial infection. These dynamic mechanisms underlying root nodule symbiosis are now described in numerous textbooks and review articles as the fundamental principles of its establishment.
Dr. Long elucidated the mechanism by which the bidirectional “molecular dialogue” between host plants and rhizobia, mediated by flavonoids and Nod factors, governs the establishment of host-specific root nodule symbiosis. Furthermore, through her discovery of calcium spiking, she revealed a fundamental principle by which chemical communication between different organisms is transduced into intracellular signal transduction, thereby laying the theoretical foundation for root nodule symbiosis research. Her findings have driven progress in the field for several decades and continue to shape the direction of research on plant-microbe interactions today.
- S. R. Long, W. J. Buikema and F. M. Ausubel. (1982) Cloning of Rhizobium meliloti nodulation genes by direct complementation of Nod-minus mutants. Nature 298:485-488.
- J. T. Mulligan and S. R. Long. (1985) Induction of Rhizobium meliloti nodC expression by plant exudate requires nodD. Proc. Natl. Acad. Sci. USA 82:6609-6613.
- N. K. Peters, J. W. Frost and S. R. Long. (1986) A plant flavone, luteolin, induces expression of Rhizobium meliloti nodulation genes. Science 233:977-980.
- J. Schwedock and S. R. Long. (1990) ATP sulfurylase activity of the nodP and nodQ gene products of Rhizobium meliloti. Nature 348:644-647.
- D.W. Ehrhardt, E.M. Atkinson and S.R. Long. (1992) Depolarization of alfalfa root hair membrane potential by Rhizobium meliloti Nod factors. Science 256: 998-1000. DOI: 10.1126/science.10744524
- R. F. Fisher and S. R. Long. (1993) Interactions of NodD at the nod box: NodD binds to two distinct sites on the same face of the helix and induces a bend in the DNA. J. Mol. Biol. 233:336-348. PMID: 8411148
- D. W. Ehrhardt, R. Wais, and S. R. Long. (1996) Calcium spiking in plant root hairs responding to Rhizobium nodulation signals. Cell 85:673-681.
- P. A. Covitz, L. S. Smith and S. R. Long. (1998) Expressed sequence tags from a root-hair-enriched Medicago truncatula cDNA library. Plant Physiol. 117:1325-1332.
- V. Oke and S. R. Long. (1999) Bacterial genes induced within the nodule during the Rhizobium-legume symbiosis. Molecular Microbiology 32 (4):837-849.
- F. Galibert, T.M. Finan, S.R. Long, A. Pühler, P. Abola, F. Ampe, F. Barloy-Hubler, M. J. Barnett, A. Becker, P. Boistard, G. Bothe, M. Boutry, L. Bowser, J. Buhrmester, E. Cadieu, D. Capela, P. Chain, A. Cowie, R. W. Davis, S. Dréano, N.A. Federspiel, R.F. Fisher, S. Gloux, T. Godrie, A. Goffeau, B. Golding, J. Gouzy, M. Gurjal, I. Hernandez-Lucas, A. Hong, L. Huizar, R.W. Hyman, T. Jones, D. Kahn, M.L. Kahn, S. Kalman, D.H. Keating, E Kiss, C. Komp, V. Lelaure, D. Masuy, C. Palm, M.C. Peck, T.M Pohl, D. Portetelle, B. Purnelle, U. Ramsperger, R. Surzycki, P. Thébault, M. Vandenbol, F.-J. Vorhölter, S. Weidner, D. H. Wells, K.Wong, K.-C. Yeh, J. Batut. (2001) The composite genome of the legume symbiont Sinorhizobium meliloti. Science 293: 668-672. DOI: 10.1126/science.1060966
- M.J. Barnett, R.F. Fisher, T. Jones, C. Komp, A.P. Abola, F. Barloy-Hubler, L. Bowser, D. Capela, F. Galibert J. Gouzy, M. Gurjal, A. Hong, L. Huizar, R.W. Hyman, D. Kahn, M.L. Kahn, S. Kalman, D.H. Keating, C. Palm, M.C. Peck, R. Surzycki, D.H. Wells, K.-C. Yeh, R.W. Davis, N.A. Federspiel, and S.R. Long. (2001). Nucleotide sequence and predicted functions of the entire Sinorhizobium meliloti. pSymA megaplasmid. Proc. Natl. Acad. Sci. USA 98 (17): 9883-9888. doi: 10.1073/pnas.161294798
- G. E. D. Oldroyd and S. R. Long. (2003) Identification and characterization of NSP2, a gene of Medicago truncatula involved in Nod factor signaling. Plant Physiology 131: 1027-1032.
- S. L. Shaw, and S. R. Long. (2003) Nod factor elicits two separable calcium responses in Medicago truncatula root hair cells. Plant Physiology 131:976-984.
- R.M. Mitra, C.A.Gleason, A. Edwards, J. Hadfield, J.A.Downie, G.E.D. Oldroyd and S.R. Long (2004). A Ca2+/calmodulin-dependent protein kinase required for symbiotic nodule development: gene identification by transcript-based cloning. Proc. Natl. Acad. Sci. USA 101 (13): 4701-4705.
- M. J. Barnett, C.J. Toman, R.F. Fisher and S. R. Long. (2004). A dual-genome symbiosis chip for coordinate study of signal exchange and development in a prokaryote-host interaction. Proc. Natl. Acad. Sci. USA 101 (47): 16636-16641.
- C.G. Starker, A.L. Para-Colmenares, L.S. Smith, R.M. Mitra, and S.R. Long (2006). Nitrogen fixation mutants of Medicago truncatula fail to support plant and bacterial symbiotic gene expression. Plant Physiology, 140: 671-680.
- D. Wang, J. Griffitts, C. Starker, E. Fedorova, E. Limpens, S. Ivanov, T. Bisseling and S. R. Long (2010) A nodule-specific protein secretory pathway required for nitrogen-fixing symbiosis. Science 327: 1126-1129.
- C.H Haney, B. Riely, D. Tricoli, D.R. Cook, D.W. Ehrhardt and S.R. Long (2011) Symbiotic rhizobia bacteria trigger a change in localization and dynamics of the Medicago truncatula receptor kinase LYK3. Plant Cell 23:2774-2787. Online / June 2011/tpc.111.086389.
- C. Lang and S.R. Long (2015). Transcriptomic and genetic analysis of differentiation in Sinorhizobium meliloti-Medicago truncatula nodulation. Molec. Plant-Microbe Interactions 28:856-868 http://dx.doi.org/10.1094/MPMI-12-14-0407-R
- M.J. Barnett, D. Solow-Cordero, S.R. Long (2019) A high-throughput system to identify inhibitors of Candidatus Liberibacter asiaticus transcription regulators. Proc.Nat.Acad.Sci. doi:10.1073/pnas.1905149116