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Most members of basic leucine zipper (bZIP) transcription factor (TF) subgroup A play important roles as positive effectors in abscisic acid (ABA) signaling during germination and/or in vegetative stress responses. In multiple plant species, one member, ABA insensitive 5 (ABI5), is a major TF that promotes seed maturation and blocks early seeding growth in response to ABA. Other members, referred to as either ABRE‐binding factors (ABFs), ABRE‐binding proteins (AREBs), or D3 protein‐binding factors (DPBFs), are implicated as major players in stress responses during vegetative growth. Studies on the proteolytic regulation of ABI5, ABF1, and ABF3 inArabidopsis thalianahave shown that the proteins have moderate degradation rates and accumulate in the presence of the proteasome inhibitor MG132. Exogenous ABA slows their degradation and the ubiquitin E3 ligase called KEEP ON GOING (KEG) is important for their degradation. However, there are some reported differences in degradation among subgroup A members. The conserved C‐terminal sequences (referred to as the C4 region) enhance degradation of ABI5 but stabilize ABF1 and ABF3. To better understand the proteolytic regulation of the ABI5/ABFs and determine whether there are differences between vegetative ABFs and ABI5, we studied the degradation of an additional family member, ABF2, and compared its in vitro degradation to that of ABI5. As previously seen for ABI5, ABF1, and ABF3, epitope‐tagged constitutively expressed ABF2 degrades in seedlings treated with cycloheximide and is stabilized following treatment with the proteasome inhibitor MG132. Tagged ABF2 protein accumulates when seedlings are treated with ABA, but its mRNA levels do not increase, suggesting that the protein is stabilized in the presence of ABA. ABF2 is also an in vitro ubiquitination substrate of the E3 ligase KEG and recombinant ABF2 is stable inkeglysates. ABF2 with a C4 deletion degrades more quickly in vitro than full‐length ABF2, as previously observed for ABF1 and ABF3, suggesting that the conserved C4 region contributes to its stability. In contrast to ABF2 and consistent with previously published work, ABI5 with C terminal deletions including an analogous C4 deletion is stabilized in vitro compared to full length ABI5. In vivo expression of an ABF1 C4 deletion protein appears to have reduced activity compared to equivalent levels of full length ABF1. Additional group A family members show similar proteolytic regulation by MG132 and ABA. Altogether, these results together with other work on ABI5 regulation suggest that the vegetative ABFs share proteolytic regulatory mechanisms that are not completely shared with ABI5.

Auxin phytohormones control most aspects of plant development through a complex and interconnected signaling network. In the presence of auxin, AUXIN/INDOLE-3-ACETIC ACID (AUX/IAA) transcriptional repressors are targeted for degradation by the SKP1-CULLIN1-F-BOX (SCF) ubiquitin-protein ligases containing TRANSPORT INHIBITOR RESISTANT 1/AUXIN SIGNALING F-BOX (TIR1/AFB). CULLIN1-neddylation is required for SCF^TIR1/AFBfunctionality, as exemplified by mutants deficient in the NEDD8-activating enzyme subunit AUXIN-RESISTANT 1 (AXR1). Here, we report a chemical biology screen that identifies small molecules requiring AXR1 to modulate plant development. We selected four molecules of interest, RubNeddin 1 to 4 (RN1 to -4), among which RN3 and RN4 trigger selective auxin responses at transcriptional, biochemical, and morphological levels. This selective activity is explained by their ability to consistently promote the interaction between TIR1 and a specific subset of AUX/IAA proteins, stimulating the degradation of particular AUX/IAA combinations. Finally, we performed a genetic screen using RN4, the RN with the greatest potential for dissecting auxin perception, which revealed that the chromatin remodeling ATPase BRAHMA is implicated in auxin-mediated apical hook development. These results demonstrate the power of selective auxin agonists to dissect auxin perception for plant developmental functions, as well as offering opportunities to discover new molecular players involved in auxin responses.

Population growth and climate change will impact food security and potentially exacerbate the environmental toll that agriculture has taken on our planet. These existential concerns demand that a passionate, interdisciplinary, and diverse community of plant science professionals is trained during the 21st century. Furthermore, societal trends that question the importance of science and expert knowledge highlight the need to better communicate the value of rigorous fundamental scientific exploration. Engaging students and the general public in the wonder of plants, and science in general, requires renewed efforts that take advantage of advances in technology and new models of funding and knowledge dissemination. In November 2018, funded by the National Science Foundation through the Arabidopsis Research and Training for the 21st century (ART 21) research coordination network, a symposium and workshop were held that included a diverse panel of students, scientists, educators, and administrators from across the US. The purpose of the workshop was to re‐envision how outreach programs are funded, evaluated, acknowledged, and shared within the plant science community. One key objective was to generate a roadmap for future efforts. We hope that this document will serve as such, by providing a comprehensive resource for students and young faculty interested in developing effective outreach programs. We also anticipate that this document will guide the formation of community partnerships to scale up currently successful outreach programs, and lead to the design of future programs that effectively engage with a more diverse student body and citizenry.