首页|Overexpression of <i>HEMA1</i> encoding glutamyl-tRNA reductase. (Special Issue: Regulation of plant primary metabolism.)

Overexpression of <i>HEMA1</i> encoding glutamyl-tRNA reductase. (Special Issue: Regulation of plant primary metabolism.)

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  • NSTL
  • Elsevier
5-Aminolevulinic acid (ALA) synthesis has been shown to be the rate limiting step of tetrapyrrole biosynthesis. Glutamyl-tRNA reductase (GluTR) is the first committed enzyme of plant ALA synthesis and is controlled by interacting regulators, such as heme and the FLU protein. Induced inactivation of the <i>HEMA1</i> gene encoding GluTR by RNAi expression in tobacco resulted in a reduced activity of Mg chelatase and Fe chelatase indicating a feed-forward regulatory mechanism that links ALA synthesis posttranslationally with late enzymes of tetrapyrrole biosynthesis (Hedtke et al., 2007). Here, the regulatory impact of GluTR was investigated by overexpression of <i>AtHEMA1</i> in <i>Arabidopsis</i> and tobacco plants. Light-dependent ALA synthesis cannot benefit from an up to 7-fold induced expression of GluTR in <i>Arabidopsis</i>. While constitutive <i>AtHEMA1</i> overexpression in tobacco stimulates ALA synthesis by 50-90% during light-exposed growth of seedlings, no increase in heme and chlorophyll contents is observed. <i>HEMA1</i> overexpression in etiolated and dark-grown <i>Arabidopsis</i> and tobacco seedlings leads to additional accumulation of protochlorophyllide. As excessive accumulation of GluTR does not correlate with increased ALA formation, it is hypothesized that ALA synthesis is additionally limited by other effectors that balance the allocation of ALA with the activity of enzymes of chlorophyll and heme biosynthesis.

biosynthesischlorophyllchloroplastsenzyme activityenzymesgene expressiongenesgrowthhaemironplant physiologyprotochlorophyllidesseedlingstobaccoArabidopsisNicotianaplantsBrassicaceaeCapparidalesdicotyledonsangiospermsSpermatophytaplantseukaryotesSolanaceaeSolanalesCapparalesheme

Schmied, J.、Hedtke, B.、Grimm, B.

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Institute of Biology, Plant Physiology, Humboldt University Berlin, Philippstr. 13, Building 12, 10115 Berlin, Germany.

2011

10.1016/j.jplph.2010.12.010

Journal of Plant Physiology

Journal of Plant Physiology

SCI
ISSN：0176-1617
年,卷(期)：2011.168(12)
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