Plants show leaf form alteration in response to changes in the surrounding environment, and this phenomenon is called heterophylly. Although heterophylly is seen across plant species, the regulatory mechanisms involved are largely unknown. Here, we investigated the mechanism underlying heterophylly in Rorippa aquatica (Brassicaceae), also known as North American lake cress. R. aquatica develops pinnately dissected leaves in submerged conditions, whereas it forms simple leaves with serrated margins in terrestrial conditions. We found that the expression levels of KNOTTED1-LIKE HOMEOBOX (KNOX1) orthologs changed in response to changes in the surrounding environment (e.g., change of ambient temperature; below or above water) and that the accumulation of gibberellin (GA), which is thought to be regulated by KNOX1 genes, also changed in the leaf primordia. We further demonstrated that exogenous GA affects the complexity of leaf form in this species. Moreover, RNA-seq revealed a relationship between light intensity and leaf form. These results suggest that regulation of GA level via KNOX1 genes is involved in regulating heterophylly in R. aquatica. The mechanism responsible for morphological diversification of leaf form among species may also govern the variation of leaf form within a species in response to environmental changes.

Differentiation of plant cells is regulated by position-dependent mechanisms rather than lineage. The maize Extra cell layers1 (Xcl1) mutation causes oblique, periclinal divisions to occur in the protoderm layer. These protodermal periclinal divisions occur at the expense of normal anticlinal divisions and cause the production of extra cell layers with epidermal characteristics, indicating that cells are differentiating according to lineage instead of position. Mutant kernels have several aleurone layers instead of one, indicating that Xcl1 alters cell division orientation in cells that divide predominantly in the anticlinal plane. Dosage analysis of Xcl1 reveals that the mutant phenotype is caused by overproduction of a normal gene product. This allows cells that have already received differentiation signals to continue to divide in aberrant planes and suggests that the timing of cell division determines differentiation. Cells that divide early and in the absence of differentiation signals use positional information, while cells that divide late after perceiving differentiation signals use lineage information instead of position.

The challenges of negotiating the first year of teaching is something that concerns not only nascent teachers, but also many teacher educators and school administrators (Dugas, 2016). This case study of two beginning teachers explores the ways these teachers navigated the pressures of institutional performativity. Interviews reveal that both teachers' identities were impacted by external data-driven learning measures. The first-year teachers wrestled with the quantifiable data that served as evidence of their merit. At times, these external expectations created a crisis in values in that the beginning teachers felt they must abandon what they knew to be effective practices and instead adopt their school norms or approaches that would meet these external demands. This research points to the ways teacher educators and school administrators must work alongside beginning teachers to be a catalyst for systemic change toward student-centered learning and away from an over emphasis on student data driving perceptions of teacher merit.

With the increased demand for culturally and linguistically relevant teaching, this paper explores the use of sound stories to cultivate empathetic understanding in undergraduate preservice teachers. I inquiry into the process of creating, writing, and performing a sound story about my family’s American Japanese imprisonment experience to better understand this teaching method and adapt it for teacher education. The inquiry reveals counter stories of agency and resistance, as well as a powerful and creative teaching tool for increasing empathy in both the teacher and students.

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