Tropes

R_www.sciencedaily.com 2015 12274.txt.txt

#Plant growth requires teamwork between two hormones The scientists used plants with mutations, which impaired the activity of brassinosteroids. They thereby discovered that these plants produced less gibberellin. As a result, the plants'germination was impaired, their growth inhibited and their flowering delayed.""The brassinosteroids are therefore necessary for the production of gibberellins--a mechanism that is highly relevant to the growth and development of plants,"says Poppenberger, Professor for the Biotechnology of Horticultural Crops. The scientists were able to show that transcription factors are responsible for this mechanism. Transcription factors are proteins that regulate gene expression. Once activated by brassinosteroids, they initiate the production of gibberellin.""We've elucidated a molecular mechanism that is fundamental to cell elongation and division in plants, "the head of the research group concludes. Dwarf cultivars, such as balcony varieties of vegetables like tomatoes and cucumbers, as well as grain varieties were selected specifically for impaired brassinosteroid metabolism, says Poppenberger.""We now understand that these defects interfere with the mechanism of action of gibberellins. In barley, for example, this results in shorter stalks with better stability and higher yields,"Poppenberger explains. These short cultivars are called semi-dwarf varieties. They were bred as early as the 1950s and 1960s when the primary aim was to improve yields. The Nobel laureate Norman Borlaug, known as the father of the green revolution, bred short-stalked wheat and rice. Coupled with intensified farming methods, these new crop varieties increased yields fivefold, preventing famines in Mexico and later China. Arraywhereas external application of gibberellins has been utilized in agriculture for several decades for example, to produce larger fruits or to obtain seedless fruits like grapes or tangerines, brassinosteroids have not been used in this manner. It would be too expensive. However, in plant breeding varieties with defects in brassinosteroid activity have been selected for, barley being a prime example.""These findings are an important step toward improving our understanding of how plant steroids work --and harnessing their potential for the breeding and production of crop plants,"says Brigitte Poppenberger r

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