ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The effects of IAA and galactose on the endogenous levels of UDP-sugars and nu-cleotides were compared between a monocotyledon, using coleoptile segments of oat (Avena sativa L. cv. Victory I) and a dicotyledon, using epicotyl segments of azuki bean (Vigna angularis Owhi and Ohashi cv. Takara). The following results were obtained:〈list xml:id="l1" style="custom"〉1Exogenously applied galactose inhibited the IAA-induced cell elongation of Avena coleoptile segments, but not that of Vigna epicotyl segments.2Galactose was not found in the neutral free sugar and phosphate sugar fractions in the control segments of either Avena or Vigna. Galactose caused a strong increase in the level of Gal-1-P but little increase in the level of free galactose in the two plant tissues.3Galactose caused a rapid decrease in the amount of UDP-glucose and an accumulation of UDP-galactose in Avena coleoptile segments. Also, galactose caused a decrease in the UTP level but affected the ATP and GTP levels only little, suggesting that galactose inhibits the UDP-glucose formation by decreasing the UTP level due to a predominant formation of UDP-galactose.4In Vigna, galactose increased the level of UDP-galactose to a lesser extent than in Avena, and was virtually without effect on the levels of UDP-glucose, UTP or other nucleotides.5In the absence of galactose, IAA caused an increase in the levels of UDP-glucose and UTP in Avena. In Vigna, IAA gave increased levels of UDP-glucose and UTP in both the presence and absence of galactose. IAA also increased the levels of ATP and GTP in both plants, suggesting that IAA stimulates the UDP-glucose formation by activating the metabolism of nucleotides and thus increasing the UTP level.From these results, we conclude that UTP is involved in the IAA action and also in the differential effects of galactose on the UDP-glucose formation, which is needed for cell wall synthesis and ensuing cell elongation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1987.tb01969.x
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