The involvement of indole-3-acetic acid in the control of stem elongation in dark- and light-grown pea (Pisum sativum) seedlings.
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.
Sorce
Carlo
C
Department of Biology, University of Pisa, via L. Ghini, 5, 56126 Pisa, Italy. csorce@biologia.unipi.it
Picciarelli
Piero
P
Calistri
Gianni
G
Lercari
Bartolomeo
B
Ceccarelli
Nello
N
D056931:Cryptochromes; D005420:Flavoproteins / Q000378:metabolism; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008027:Light; D018532:Pisum sativum / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D010834:Phytochrome / Q000378:metabolism; D018547:Plant Stems / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects
D056931:Cryptochromes; D005420:Flavoproteins; D007210:Indoleacetic Acids; D010834:Phytochrome; C030737:indoleacetic acid