Growing barley (Hordeum vulgare L.) plants for 7 days on NaCl solutions (20–200 mM) decreased chlorophyll (Chl) a and b content with respect to that in untreated control plants. The content of free proline and the plant ability to synthesize 5-aminolevulinic acid (ALA) started to increase in parallel at salt concentrations of 20–50 mM. The maximum amount of ALA accumulated in plants grown at 100 mM NaCl was twofold higher than in control plants grown on fresh water. In this case the proline content increased 2.8-fold. On further increase in salt concentration, the rate of ALA accumulation decreased, approaching control values at 150 mM NaCl; even lower rates were observed at 200 mM NaCl. The reduced ability to synthesize ALA was accompanied by an increase in proline content. The albino tissue of plants treated at the seed stage with the antibiotic streptomycin lost its ability to synthesize ALA needed for Chl formation. The proline content in the albino tissue was tenfold higher than in control green plants and was 30-fold higher when the plants were grown on solutions with 100 mM NaCl. No effect of NaCl on ALA-dehydratase activity was noted. As NaCl concentration was raised, there occurred the decrease in magnesium chelatase activity, accumulation of reactive oxygen species (ROS), the increase in ascorbate peroxidase activity, and a slight decrease in lipid peroxidation level. Growing plants in the presence of 150 mM NaCl and 10 or 60 mg/l exogenous ALA led to the increase in proline content (by a factor of 1.8 and 4.2, respectively) and to the decrease in ROS content, in comparison with plants grown on salt solutions without ALA. Furthermore, in the presence of exogenous ALA, the parameters of seedling growth became similar to those of NaCl-untreated plants. The role of ALA in plants as an antistress agent is considered. ALA is supposed to confer tolerance to salt stress by taking part in Chl and heme biosynthesis and also through functioning as a plant growth regulator. A hypothesis is put forward that the impairment of ALA-synthesizing ability may redirect metabolic conversions of glutamic acid from Chl and heme synthesis to the proline synthesis pathway, which would stimulate proline biosynthesis and improve salt tolerance.
Russian Journal of Plant Physiology – Springer Journals
Published: Oct 31, 2010
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera