Team: Regulation of intracellular processes

Laboratory of Plant Cell Biophysics and Biochemistry

Head of the team:

N.G. Averina, D. Sc., Professor

E-mail: averina@ibp.org.by

Main research trends:

  1. Organization and regulatory mechanisms of plant tetrapyrrol biosynthesis.
  2. Plastid-nucleus interaction and intracellular signaling.
  3. Practical application of chlorophyll biosynthesis precursors in agriculture.

Important results:

  • The existence of discrete and spatially isolated branches of heme and chlorophyll (Chl) biosynthesis was revealed. Independent pools of 5-aminolevulinic acid (ALA) and protoporphyrin IX (Proto), two isoforms of glutamate-1-semialdehyde aminotransferases as well as different mechanisms of regulation provide the functioning heme and Chl branches.
  • New conception on regulation of the activity of ALA-synthesizing reactions was advanced. It was established that retroinhibition of ALA synthesis by protochlorophyllide takes place only within a triple complex: Glu-tRNA Glu-synthetase – glutamyl-tRNA Glu – Glu-tRNA Glu-reductase.
  • Light dependence of ALA synthesis destined for formation of Chl a and b of light-harvesting complexes, as well as for Chl a of internal antennas in two photosystem cores was found.
  • Original methods for differential spectrophotometry of some porphyrins were developed. Photophysical and photochemical processes, underlying photodynamic damages of plant cells under photodynamic herbicides, were studied. New compositions of these herbicides (3 inventor’s certificates) were developed, the nature of their selectivity was studied and the biotechnology of their agricultural application was proposed.
  • It was revealed that Chl and heme precursors (protoporphyrin IX and Mg-protoporphyrin IX) are accumulated in plastids in a monomeric state and energetically isolated from carotenoids that creates conditions for their involvement in photodynamic processes.
  • Finding the effective excitation energy transfer from Proto and Mg-Proto to photoactive form of protochlorophyllide and establishment of a role of Mg-Proto as negative plastid signal in controling expression of CHLH and CHLI subunits of Mg-chelatase discovered the new mechanisms of plant protection from photodynamic processes induced by the porphyrins.
  • It was established that in contrast to higher plants algae’s pigments are very resistant to photooxidation triggered by photodynamic herbicides. The mechanisms involved are stimulation of ALA and Chl synthesis, increasing a level of phytohormone cytokinin, activation of ascorbate peroxidase as well as excretion of herbicides into medium of incubation.
  • Porphyrin precursor ALA was revealed to exhibit properties of plant growth regulator. The basis of ALA action is considerable increase in accumulation of endogenous phytohormone cytokinins as well as stabilization of some Chl biosynthesis enzymes.
  • Study on the effects of light and cytokinins on the Chl biosynthesis system led to the conception on independent transduction mechanisms of light and phytohormonal signals to general targets – genes encoding key enzymes of Chl biosynthesis.
  • It has been found that ALA as antistress agent improves plant salt tolerance by activating Chl and heme biosynthesis and manifesting its plant growth regulator properties. A hypothesis has been proposed that inhibition of ALA biosynthesis in vivo switches the glutamic acid metabolism from Chl and heme synthesis to proline formation leading to stimulation of the osmolite biosynthesis and improving plant salt tolerance.
  • The new compositions for incrustation of crop seeds containing preparations of ALA as biologically active components were developed.

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