The involvement of indole-3-acetic acid in the control of stem elongation in dark- and light-grown pea (Pisum sativum) seedlings |
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Authors: | Sorce Carlo Picciarelli Piero Calistri Gianni Lercari Bartolomeo Ceccarelli Nello |
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Institution: | Department of Biology, University of Pisa, via L. Ghini, 5, 56126 Pisa, Italy. csorce@biologia.unipi.it |
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Abstract: | We investigated the role of auxin on stem elongation in pea (Pisum sativum L.) grown for 10d in continuous darkness or under low-irradiance blue, red, far red and white light. The third internode of treated seedlings was peeled and the tissues (epidermis and cortex+central cylinder) were separately analyzed for the concentration of free and conjugated indole-3-acetic acid (IAA). Under red, far red and white light internode elongation was linearly related with the free IAA content of all internode tissues, suggesting that phytochrome-dependent inhibition of stem growth may be mediated by a decrease of free IAA levels in pea seedlings. The correlation between IAA and internode elongation, however, did not hold for blue light-grown seedlings. The hypothesis that the growth response under low-irradiance blue light might be correlated with the lack of phytochrome B signalling and changes in gibberellin metabolism is discussed in view of current knowledge on hormonal control of stem growth. |
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Keywords: | Auxin Cryptochrome Growth Phytochrome Wavelength |
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