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Elastic electron-proton scattering (e-p) and the spectroscopy of hydrogen atoms are the two methods traditionally used to determine the proton charge radius, r p . In 2010, a new method using muonic hydrogen atoms 1 found a substantial discrepancy compared with previous results 2 , which became known as the 'proton radius puzzle'. Despite experimental and theoretical efforts, the puzzle remains unresolved. In fact, there is a discrepancy between the two most recent spectroscopic measurements conducted on ordinary hydrogen 3,4 . Here we report on the proton charge radius experiment at Jefferson Laboratory (PRad), a high-precision e-p experiment that was established after the discrepancy was identified. We used a magnetic-spectrometer-free method along with a windowless hydrogen gas target, which overcame several limitations of previous e-p experiments and enabled measurements at very small forward-scattering angles. Our result, r p  = 0.831 ± 0.007 stat  ± 0.012 syst  femtometres, is smaller than the most recent high-precision e-p measurement 5 and 2.7 standard deviations smaller than the average of all e-p experimental results 6 . The smaller r p we have now measured supports the value found by two previous muonic hydrogen experiments 1,7 . In addition, our finding agrees with the revised value (announced in 2019) for the Rydberg constant 8 -one of the most accurately evaluated fundamental constants in physics.

Both physical barriers and reactive phytochemicals represent two important components of a plant's defence system against environmental stress. However, these two defence systems have generally been studied independently. Here, we have taken an exclusive opportunity to investigate the connection between a chemical-based plant defence system, represented by the glucosinolate-myrosinase system, and a physical barrier, represented by the cuticle, using Arabidopsis myrosinase (thioglucosidase; TGG) mutants. The tgg1, single and tgg1 tgg2 double mutants showed morphological changes compared to wild-type plants visible as changes in pavement cells, stomatal cells and the ultrastructure of the cuticle. Extensive metabolite analyses of leaves from tgg mutants and wild-type Arabidopsis plants showed altered levels of cuticular fatty acids, fatty acid phytyl esters, glucosinolates, and indole compounds in tgg single and double mutants as compared to wild-type plants. These results point to a close and novel association between chemical defence systems and physical defence barriers.