The American Journal of Botany: Chronicling a Century of Plant Science Discovery
From foundational auxin experiments to modern DNA technologies, explore how the AJB has documented the evolution of botanical science.
More Than Just Pages—A Botanical Legacy
Imagine a single publication that has captured virtually every major breakthrough in plant science over the past century—from the discovery of plant hormones to the latest DNA sequencing technologies.
Since its establishment in 1914, the American Journal of Botany (AJB) has served as both witness and contributor to the remarkable evolution of botanical science, maintaining its position as the flagship journal of the Botanical Society of America. This living chronicle continues to document how plants function, evolve, and interact with our world, preserving foundational knowledge while showcasing cutting-edge research that shapes our understanding of the plant kingdom.
The AJB: A Living Chronicle of Botanical Science
From foundational insights to modern discoveries, the journal has documented over a century of botanical progress.
From Foundational Insights to Modern Discoveries
The American Journal of Botany has stood as a cornerstone of plant science for over a century, publishing peer-reviewed research that spans all areas of plant biology. The journal's comprehensive scope includes plant structure, function, development, diversity, genetics, evolution, and systematics, examining everything from molecular processes to ecosystem-level dynamics across all plant groups and allied organisms like cyanobacteria, algae, fungi, and lichens 6 .
In 2014, AJB marked a significant milestone: entering its second century of publication 4 . This transition reflected both its enduring legacy and its adaptability in an rapidly changing scientific landscape. Unlike static historical records, the journal has continuously evolved to address emerging questions and incorporate new technologies, maintaining its relevance across generations of botanists.
1914
American Journal of Botany founded as the official publication of the Botanical Society of America.
1939
Publication of Thimann and Schneider's seminal auxin research that shaped plant hormone studies.
1980s
Early adoption of DNA fingerprinting technologies for botanical research.
2012-2016
Special issues on next-generation sequencing, plant tropisms, polyploidy, and mutualisms 2 .
2014
AJB enters its second century of publication 4 .
Special Issues: Capturing Botanical Frontiers
One way AJB has chronicled the advancement of plant science is through its specialized thematic issues that capture the state of knowledge in rapidly evolving fields. These collections represent snapshots of scientific progress at specific moments in time, highlighting both consensus and controversy in botanical research.
Next-Generation Sequencing
Methods and applications in botany (2012)
Plant Tropisms
Advances in directional growth responses (2013)
Polyploidy
Evolutionary importance of genome duplication (2016)
Mutualisms
Ecology and coevolution of intimate relationships (2016)
Unearthing Foundations: The Auxin Experiment That Shaped Plant Biology
Thimann and Schneider's 1939 investigation laid the groundwork for modern plant hormone research.
The Mystery of Plant Growth
For centuries, scientists observed that plants grow toward light and their roots downward, but the mechanism behind these directional growth patterns—called tropisms—remained mysterious. Charles Darwin and his son Francis had demonstrated that some "influence" was transmitted from plant tips to growing regions, but the chemical nature of this influence was unknown. By the early 20th century, scientists were hunting for the elusive growth-promoting substance we now know as auxin—from the Greek "auxein" meaning "to grow" 1 .
Plant growth responses to directional light, similar to early tropism experiments.
Methodological Breakthroughs: How They Tested Auxins
Thimann and Schneider employed two sophisticated (for their time) bioassays to compare the activity of seven auxinic compounds:
Avena Coleoptile Test
Using etiolated stem sections from oats (Avena sativa), they measured coleoptile elongation after incubation in auxin solutions .
Pisum Split Stem Test
They split etiolated pea stems and measured the degree of curvature induced by different auxins .
Auxin Compounds Studied by Thimann and Schneider (1939)
| Compound | Full Name | Source/Nature | Relative Activity in Avena |
|---|---|---|---|
| IAA | Indole-3-acetic acid | Isolated from human urine, yeast, fungi | Standard (100%) |
| IBA | Indole-3-butyric acid | Synthetic compound | Highly active |
| NAA | Naphthalene acetic acid | Synthetic compound | Highly active |
| IPrA | Indole-3-propionic acid | Synthetic compound | Weakly active |
| PAA (ΦAA) | Phenylacetic acid | Naturally occurring | Variable by species |
Key Findings from Thimann and Schneider's Experiment
| Discovery | Significance | Impact on Future Research |
|---|---|---|
| Species-specific auxin responses | Challenged assumption of universal response patterns | Led to understanding of species-specific receptor and signaling systems |
| IBA as highly active auxin | Identified important synthetic auxin | IBA later found to occur naturally in plants; widely used in horticulture for rooting |
| Molecular structure determines activity | Established structure-activity relationships | Guided development of synthetic auxins for agricultural use |
| Pisum more sensitive than Avena | Revealed model-dependent differences | Influenced choice of model systems for future hormone studies |
The Present: Botanical Science in the Molecular Age
From physiology to molecular mechanisms, DNA technologies have revolutionized plant biology.
From Physiology to Molecular Mechanisms
While Thimann and Schneider could only observe plant responses to auxins, modern research has unraveled the molecular machinery behind these phenomena. We now understand that auxin influences plant growth through three main mechanisms: biosynthesis (how plants produce auxin), transport (how auxin moves through tissues), and signaling (how auxin is perceived and transduced into growth responses) .
The Arabidopsis thaliana root elongation assay has largely replaced the Avena test as the standard bioassay, leveraging genetic tools in this model organism to identify mutants with altered auxin responses . These approaches have revealed entire gene families responsible for auxin transport and signaling, connecting the physiological observations of early researchers with precise molecular mechanisms.
Auxin Signaling Pathway
Visualization of molecular auxin signaling mechanisms
The DNA Revolution in Plant Biology
Just as auxin research transformed our understanding of plant growth, DNA technologies have revolutionized how botanists identify, classify, and understand relationships between plant species. The development of DNA fingerprinting in the 1980s provided an unprecedented ability to distinguish individual genotypes, transforming fields like ecology, evolution, and conservation 5 .
RFLP with Minisatellite Probes
1980s-1990s
Cultivar identification, clonal verification
Required large DNA amounts, radioactive detection
PCR-based Markers
1990s-now
Population genetics, kinship analysis, mapping
Limited to known genetic regions
Next-Generation Sequencing
2005-beyond
Genotyping-by-sequencing, phylogenomics
Computational challenges for large genomes
The Future of Botany: Emerging Questions and Technologies
Next-generation approaches are shaping the future of plant science research.
Unanswered Questions in Auxin Biology
Despite a century of progress, fundamental questions about auxin biology remain unanswered. Current researchers are investigating how auxin biosynthesis pathways are regulated, how transport proteins are organized at the cellular level, and how the same signaling molecule can produce diverse responses in different tissues and species .
The complexity of auxin's roles—from coordinating tropic responses to regulating organ formation—ensures that this field will remain active for the foreseeable future.
"The steady and collective advance rather than of individual contributions"
Emerging Research Areas
- Plant-microbe interactions New
- Climate change adaptation Growing
- Synthetic biology applications Emerging
- Phylogenomics Expanding
- Eco-evolutionary dynamics Integrative
Next-Generation Botany
As DNA sequencing technologies continue to advance, they enable approaches that were unimaginable to earlier botanists. High-throughput sequencing allows researchers to sequence entire plant genomes quickly and inexpensively, while genotyping-by-sequencing approaches facilitate the study of genetic diversity in natural populations 5 .
These technologies are accelerating discoveries in plant evolutionary history, adaptive mechanisms, and functional genetics.
The future of botany also lies in integration—connecting genomic information with physiological function, ecological interactions, and evolutionary history. As technologies advance, botanical research will continue to reveal how plants develop, function, and evolve, addressing critical challenges like climate change, food security, and biodiversity conservation.
The Scientist's Toolkit: Essential Research Tools
From simple assays to molecular reagents, botanical research relies on specialized tools.
Bioassay Systems
From the Avena coleoptile test to Arabidopsis root elongation assays, these controlled systems allow quantification of plant responses .
Model Organisms
Species like Arabidopsis thaliana enable genetic approaches impossible in other species.
Molecular Markers
DNA-based tools allow researchers to identify genotypes and track genes 5 .
Growth Regulators
Compounds like NAA and IBA remain essential for manipulating plant growth .
A Continuous Tradition of Botanical Discovery
The American Journal of Botany's journey from documenting early auxin experiments to showcasing contemporary genomic research reflects the broader evolution of botany as a discipline.
What began as observational science and simple growth assays has transformed into a molecular science capable of manipulating genetic pathways and sequencing entire genomes. Yet throughout this transformation, the fundamental questions have remained remarkably consistent: How do plants grow and develop? How do they respond to their environment? How are plant species related and how have they evolved?
As the AJB enters its second century, it continues to fulfill its mission as both archive and accelerator of botanical knowledge. The journal's pages tell a story of collective advancement—what Thimann and Schneider described as "a steady and collective advance rather than of individual contributions" . This collaborative spirit, combined with rapidly evolving technologies, ensures that the future of botanical research will be as dynamic and fruitful as its past.
For researchers and plant enthusiasts alike, the American Journal of Botany remains an essential window into the fascinating world of plant science, chronicling our ongoing quest to understand the botanical world in all its complexity and beauty.