Recognition and response to prospective competitors are crucial variables that must be considered in resource distribution and utilization in plant communities. Associated behaviors are largely mediated through the exchange of low-molecular weight exudates. These cues can significantly alter the root system architecture (RSA) between neighboring plants and are routinely sensitive enough to distinguish between plants of the same or different accessions, a phenomenon known as kin recognition (KR). Such refined discrimination of identity, based on the composition and detection of patterns of exudate signals is remarkable and provides insight into the chemical ecology of plant-plant interactions. The discovery that KR occurs in Arabidopsis thaliana provides a model system to resolve many of the mechanistic questions associated with this process. We hypothesized that the low-molecular weight cues which direct changes to the RSA during KR was driven by nutrient availability. Here we present evidence in support of a nutrient-inducible model for KR. Our findings underscore how exudate production and detection are influenced by nutrient availability as well as how this information is integrated into 'decisions' about competition and root system architecture which may have broader impacts on community composition.

Organocatalysis is an emerging field in which small metal-free organic structures catalyze a diversity of reactions with remarkable stereoselectivity. The ability to selectively switch on such pathways upon demand has proven to be a valuable tool in biological systems. Light as a trigger provides the ultimate spatial and temporal control of activation. However, there have been limited examples of photo triggered catalytic systems. Herein, we describe the synthesis and application of a caged proline system that can initiate organocatalysis upon irradiation. The caged proline was generated using the highly efficient 4-carboxy-5,7-dinitroindolinyl (CDNI) photocleavable protecting group in a 4-step synthesis. Advantages of this system include water solubility, biocompatibility, high quantum yield for catalyst release, and responsiveness to two-photon excitation. We showed the light triggered catalysis of a crossed aldol, a Mannich, and a self-aldol condensation reaction. We also demonstrated light initiated catalysis leading to the formation of a biocide in situ, which resulted in the growth inhibition of E. coli, with as little as 3 minutes of irradiation. This technique can be broadly applied to other systems by which the formation of active forms of drugs can be catalytically assembled remotely via two-photon irradiation.

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