A joint study published in Cell by the teams headed by Dr. Miquel Coll at the Institute for Research in Biomedicine (IRB Barcelona) and the Institute of Molecular Biology of the CSIC (Consejo Superior de Investigationes Cientificas), both in Barcelona, and Dr. Dolf Weijers at the University of Wageningen, in the Netherlands, has unravelled the mystery behind how the plant hormones called auxins activate multiple vital plant functions through various gene transcription factors. Auxins are plant hormones that control growth and development, that is to say, they determine the size and structure of the plant. Among their many activities, auxins favor cell growth, root initiation, flowering, fruit setting, and delay ripening. Auxins have practical applications and are used in agriculture to produce seedless fruit, to prevent fruit drop, and to promote rooting, in addition to being used as herbicides. The biomedical applications of these hormones as anti-tumor agents and to facilitate somatic cell reprogramming (the cells that form tissues) to stem cells are also being investigated. The effects of auxins in plants were first observed by Darwin in 1881, and since then this hormone has been the focus of many studies. However, although it was known how and where auxin is synthesized in the plant, how it is transported, and the receptors on which it acts, it was unclear how a hormone could trigger such diverse processes. At the molecular level, the hormone serves to unblock a transcription factor, a DNA-binding protein, which in turn activates or represses a specific group of genes. Some plants have more than 20 distinct auxin-regulated transcription factors.
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