#PlantScienceClassics #4: Arabidopsis thaliana suggested as model plant. In 1943 botanist Friedrich Laibach suggested A. thaliana as model organism for plant science. But the community was not ready yet - it took them another 40 years to see the light… doi.org/10.7287/peerj.…
Laibach started work on A. thaliana in 1907, when, for his PhD-thesis, he determined the number of chromosomes in different plants he collected around his hometown Limburg, or @UniBonn, where he worked. A. thaliana only had 5 chromosomes, one of the fewest he found.
In his 1943 paper, Laibach points out the benefits of working with A. thaliana, such as easy to grow, small genome, short lifecycle, high seed yield, can be crossed & mutated…), pointing out how comparable it is to the ‘prime example’ of models: #Drosophila melanogaster.
This simplicity was one of the reason he took a liking to the weed. The other was the geographical distribution. It seemed to grow everywhere, and Laibach & his colleagues collected seeds from accessions everywhere they traveled, starting work on #NaturalVariation in 1940.
This resulted in ‘The LAIBACH Standard Collection of Natural Races’ – the precursor to the modern @ABRC_OSU, @NascArabidopsis & @riken_en seed stock-centers. By 1943 Laibach felt that he & his team had established A. thaliana sufficiently to propose it as general plant model.
However, only very few pioneers shared Laibach’s vision at this point, among them John Langridge from the @UniofAdelaide, who even managed to publish a @Nature paper on A. thaliana already in 1955, & György Pál Rédei from Hungary.
Rédei had fled his native Hungary to the US, escaping communism & #Lysenkoism, & carrying with him A. thaliana seeds he had received from Laibach. Establishing his own lab @Mizzou, he continued Laibach’s pioneering work, creating, among other things, the Col-0 & Ler plant lines.
In 1975 he repeated Laibach’s call to adopt A. thaliana as model plant, but, like Laibach, with little success. In fact, because his peers believed so little in A. thaliana as a model, he was unable to obtain funding from the @NSF for decades. doi.org/10.1146/annure…
It was only in the 1980s,with the advent of molecular biology, that everybody finally agreed that the plant sciences absolutely required a model to conduct modern research. A @ScienceMagazine paper by Elliot Meyerowitz announced the adoption of A. thaliana as plant model in 1985.
The overwhelming success of this decision needs no pointing out, but you do have to wonder where we would be today, had more people shared Laibach or Rédei’s vision at the time these pioneers established A. thaliana as model plant in the 1970s, and even 1940s.
A quick addendum in reference to #PlantScienceClassics #2: Laibach’s student Erna Reinholz established x-ray mutagenesis of A. thaliana, curiously referencing Muller’s 1927 @ScienceMagazine paper, as well as a 1929 paper by Emmy Stein – but also ignoring her pioneering 1921 work.
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Ethylene is a gaseous #phytohormone with a wide range of roles from plant development to immunity. Ernest Starling in 1905 defined a hormone as mobile chemical messenger synthesized by a multicellular organism, that has physiological activity distant from the site of synthesis.
The effect of ethylene on plants was first noted in the 1900s, when it leaked from illumination gas used in lamps and affected plants nearby. But it was Dimitry Neljubow, who in a series of experiments identified ethlyene as the active substance in the illumination gas in 1905.
#PlantScienceClassics #17: The Mildew Resistance Locus O (MLO). 80 years ago Rudolf Freisleben & Alfred Lein created the first powdery mildew resistant barley plant. 30yrs ago the gene was mapped, 25yrs ago cloned-yet it's mode of action remains a mystery. doi.org/10.1007/BF0148…
Powdery mildew is a fungal disease of many crop plants, most prominently maybe barley and wheat, where outbreaks can reduce grain quality & yield, and ruin complete harvests. Visible are the fluffy patches formed by the fungus (Blumeria graminis f. sp. hordei).
Freisleben used radiation-induced mutagenesis to create the barley 𝘮𝘭𝘰 mutant, which showed full resistant to this pathogen. A massive agricultural breakthrough!
See also Classic #2, to read about how Emmy Stein has developed this technique in 1921:
#PlantScienceClassics #16: A linkage map of Arabidopsis thaliana. In 1983 the legendary Maarten Koornneef published a genetic map of A. thaliana, the basis for genetic work & an important contribution towards the acceptance of Arabidopsis as plant model. doi.org/10.1093/oxford…
In the early 1980s scientists finally adopted A. thaliana as model plant. At this point, several mutants were available, but their positions in the genome were mostly unknown. This was years before genome sequences became available,&genetic maps were still based on recombination.
Arabidopsis pioneer György Rédei did linkage analyses with 14 loci in the 1960s, but his genetic map from 1965 suggested 6 linkage groups – 1 more than chromosomes. Curiously, A. D. McKelvie created another map in parallel - & found 4 groups, 1 less than chromosomes.
#PlantScienceClassics #15 #PlantScienceFails #1: The auxin-independent (axi) Nicotiana tabacum lines. In 1992 Richard Walden et al. (specifically co-worker Inge Czaja) published activation-tagged axi protoplasts @ScienceMagazine that could divide&grow in the absence of any auxin!
The development of plant transformation in the early 1980s (classics #6&13) was inspirational for many scientists. Among them was Richard Walden, who teamed up with plant transformation pioneers Barbara & Thomas Hohn to leverage this advance to develop the “Agroinfection" method.
He then joined the next transformation pioneer, Jeff Schell, to develop more such tools. Their first was Activation-Tagging: 4 CaMV 35S enhancers (classic#9) were placed at the RB of the T-DNA. That way, they would overexpress the plant gene next to which the T-DNA was inserted.
#PlantScienceClassics #14: Mendelian inheritance. In 1866 Gregor Mendel published his work on dominant/recessive trait inheritance in peas, establishing the hereditary rules on which modern genetics is based. But nobody cared,& his scientific career ended. biodiversitylibrary.org/page/48299076
Mendel had always been interested in nature, and grew/kept and observed plants and bees in his parent’s garden. He later decided to become a monk and teacher. However, he failed teacher’s exam in 1850 & 1856, & eventually settled on being a monk and substitute teacher.
He satisfied his curiosity as a naturalist by keeping and observing plants and bees in the monastery garden, and eventually became interested in how traits are determined through generations. So he started to conduct crossing experiments with mice with grey or white fur.
Do you know Daisy Roulland-Dussoix? She is one of the discoverers of restriction enzymes, who’s findings paved the way for the development of recombinant DNA and cloning technologies. Accordingly, the finding was rewarded with a #NobelPrize. But the prize didn’t go to her... 🧵👇
Daisy Roulland-Dussoix worked with Werner Arber to study the mechanism for the observed host-specificity of λ Phages. It was known from an important 1953 paper (Bertani & Weigle) that phages, that had replicated in a certain E. coli strain, could only re-infect the same strain.
Roulland-Dussoix & Arber showed that host-specificity is linked with the phage’s DNA. Using phages carrying radiolabeled DNA, they showed that progeny with 2 parental DNA strands retained specificity, while progeny with newly synthesized daughter strands could adapt to new hosts.