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A spatiotemporally regulated transcriptional complex underlies heteroblastic development of leaf hairs in Arabidopsis thaliana

Full PDF link Synopsis Age‐dependent development of leaf hairs (trichomes) on the abaxial (lower) leaf surface in Arabidopsis is regulated by integration of positional and temporal cues via a transcriptional complex comprising the leaf abaxial fate determinant KAN1 and the AP2‐like transcription factor TOE1 acting as a developmental timer. AP2‐like proteins, including TOE1, repress abaxial trichome formation in juvenile leaves. TOE1 forms a repressive complex with KAN1. KAN1‐ complex binds to the 3′ downstream sequence of GL1, a master regulator of leaf trichome production.

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Nonrandom domain organization of the Arabidopsis genome at the nuclear periphery

Full PDF link Abstract The nuclear space is not a homogeneous biochemical environment. Many studies have demonstrated that the transcriptional activity of a gene is linked to its positioning within the nuclear space. Following the discovery of lamin-associated domains (LADs), which are transcriptionally repressed chromatin regions, the nonrandom positioning of chromatin at the nuclear periphery and its biological relevance have been studied extensively in animals. However, it remains unknown whether comparable chromatin organizations exist in plants.

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Cytokinin Signaling Activates WUSCHEL Expression during Axillary Meristem Initiation

Full PDF link ABSTRACT The homeodomain transcription factor WUSCHEL (WUS) defines the shoot stem cell niche, but the mechanisms underlying the establishment of WUS expression remain unclear. Here, we show that cytokinin signaling precedes WUS expression in leaf axils and activates WUS expression de novo in the leaf axil to promote axillary meristem initiation. Furthermore, type-B Arabidopsis response regulator proteins, which are transcriptional activators in the cytokinin signaling pathway, directly bind to the WUS promoter and activate its expression.

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A Two-Step Model for de Novo Activation of WUSCHEL during Plant Shoot Regeneration

Full PDF link ABSTRACT Plant cells are totipotent and competent to regenerate from differentiated organs. It has been known for six decades that cytokinin-rich medium induces shoot regeneration from callus cells. However, the underlying molecular mechanism remains elusive. The homeodomain transcription factor WUSCHEL (WUS) is essential for de novo establishment of the shoot stem cell niche in Arabidopsis thaliana. We found that WUS-positive (WUS+) cells mark the shoot progenitor region during regeneration.

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Jasmonate response decay and defense metabolite accumulation contributes to age-regulated dynamics of plant insect resistance

Full PDF link Abstract Immunity deteriorates with age in animals but comparatively little is known about the temporal regulation of plant resistance to herbivores. The phytohormone jasmonate (JA) is a key regulator of plant insect defense. Here, we show that the JA response decays progressively in Arabidopsis. We show that this decay is regulated by the miR156-targeted SQUAMOSA PROMOTER BINDING PROTEIN-LIKE9 (SPL9) group of proteins, which can interact with JA ZIM-domain (JAZ) proteins, including JAZ3.

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