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Mechanisms of Age-Dependent Response to Winter Temperature in Perennial Flowering of Arabis alpina

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Science  31 May 2013:
Vol. 340, Issue 6136, pp. 1094-1097
DOI: 10.1126/science.1234116

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Multiple Inputs to Flowering

Perennial plants need to cycle through an extended vegetative phase, in a process known as vernalization, before they initiate flowering. Bergonzi et al. (p. 1094) and Zhou et al. (p. 1097) studied how molecular signals translate environmental information—such as exposure to a winter season or changes in daylength and physiological information, such as age of the plant—into signals that promote flowering. In both Arabis alpina and Cardamine flexuosa, age and vernalization pathways are integrated through the regulation of microRNAs miR156 and miR172.

Abstract

Perennial plants live for more than 1 year and flower only after an extended vegetative phase. We used Arabis alpina, a perennial relative of annual Arabidopsis thaliana, to study how increasing age and exposure to winter cold (vernalization) coordinate to establish competence to flower. We show that the APETALA2 transcription factor, a target of microRNA miR172, prevents flowering before vernalization. Additionally, miR156 levels decline as A. alpina ages, causing increased production of SPL (SQUAMOSA PROMOTER BINDING PROTEIN LIKE) transcription factors and ensuring that flowering occurs in response to cold. The age at which plants respond to vernalization can be altered by manipulating miR156 levels. Although miR156 and miR172 levels are uncoupled in A. alpina, miR156 abundance represents the timer controlling age-dependent flowering responses to cold.

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