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Plant developmental transitions: the role of microRNAs and sugars

Full PDF link Introduction Understanding the reproducibility of developmental programs between individuals of the same multicellular organism is a fundamental challenge in biology. This developmental precision reflects the conserved and intrinsic mechanisms that temporally regulate all the aspects of biological processes during development. The cues that guide these developmental events can also include extrinsic inputs, such as nutrients, light and temperature. By contrast to animals, plants utilize different developmental programs from juvenility to maturity.

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An Intrinsic MicroRNA Timer Regulates Progressive Decline in Shoot Regenerative Capacity in Plants

Full PDF link Abstract Plant cells are totipotent and competent to regenerate from differentiated organs. It has been shown that two phytohormones, auxin and cytokinin, play critical roles within this process. As in animals, the regenerative capacity declines with age in plants, but the molecular basis for this phenomenon remains elusive. Here, we demonstrate that an age-regulated microRNA, miR156, regulates shoot regenerative capacity. As a plant ages, the gradual increase in miR156-targeted SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors leads to the progressive decline in shoot regenerative capacity.

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Temporal control of leaf complexity by miRNA-regulated licensing of protein complexes

Full PDF link Summary The tremendous diversity of leaf shapes has caught the attention of naturalists for centuries. In addition to interspecific and intraspecific differences, leaf morphologies may differ in single plants according to age, a phenomenon known as heteroblasty. In Arabidopsis thaliana, the progression from the juvenile to the adult phase is characterized by increased leaf serration. A similar trend is seen in species with more complex leaves, such as the A.

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Regulation of flowering time by the miR156-mediated age pathway

Full PDF link Abstract Precise flowering time is critical to reproductive success. In response to diverse exogenous and endogenous cues including age, hormones, photoperiod, and temperature, the floral transition is controlled by a complex regulatory network, which involves extensive crosstalks, feedback, or feedforward loops between the components within flowering time pathways. The newly identified age pathway, which is controlled by microRNA156 (miR156) and its target SQUAMOSA PROMOTER BINDING-LIKE (SPL) transcription factors, ensures plants flower under non-inductive conditions.

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Molecular Basis of Age-Dependent Vernalization in Cardamine flexuosa

Full PDF link Abstract Plants flower in response to many varied cues, such as temperature, photoperiod, and age. The floral transition of Cardamine flexuosa, a herbaceous biennial-to-perennial plant, requires exposure to cold temperature, a treatment known as vernalization. C. flexuosa younger than 5 weeks old are not fully responsive to cold treatment. We demonstrate that the levels of two age-regulated microRNAs, miR156 and miR172, regulate the timing of sensitivity in response to vernalization.

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