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Why is lead interferes with the wheat to grow

Lead interferes with plant photosynthesis, but to some extent the effect of lead can be compensated by selenium.


Green chloroplasts in the cells of a fern. (Photo: Carolina Biological Supply Company / Flickr.com.)

Green chloroplasts in the cells of a fern. (Photo: Carolina Biological Supply Company / Flickrc.om.)”

Industrial production and transport, which are increasing, not only pollute the air but also the soil, and among the most serious pollutants are heavy metals such as lead. It is known that in contaminated soils plants and wild and cultivated man, grow worse. But why is this happening? What pollutants are to blame and exactly how they act on plants?

To find out, researchers from the Institute of theoretical and experimental Biophysics (ITEB) RAS, Institute of basic problems of biology RAS and the Russian state agrarian correspondence University conducted experiments with one of the most popular crops – soft wheat (Triticum aestivum).

It was grown on soils with different levels of contamination with lead – and it turned out that the lead plants to lose their normal color and become white or, scientifically speaking, etiolirovannye. Normal green color was only on the tips of the leaves. Wheat looked like she didn’t have enough light, although light (and moisture) was enough. In addition, soil with lead plants grew much slower.

According to Galina Semenova, candidate of biological Sciences and senior researcher of the Laboratory of mechanisms of the organization of biostructures ITEB RAS, in cells of white leaves was broken the mechanism of formation of chloroplasts – the cellular organelles in which photosynthesis and svetosavlje which contain the green pigment chlorophyll.

Instead of normal chloroplasts in plants was the so-called residents in which chlorophyll is almost there. In photosynthesis there should be oxygen plants with oxygen almost residents are not isolated, instead, they accumulated hydrogen peroxide indicator of oxidative stress.

On the other hand, recent studies have shown that if you add to the soil in small doses of selenium (in small – if Selena much, it becomes dangerous for the plants), the plants will become more resistant to frost, drought and exposure to heavy metals. So Galina Semenova and her colleagues were interested to see if selenium to suppress the negative effect of lead. Selenium could: even if the lead in soil was toxic levels, the wheat grew so fast and gained such a biomass, like no lead in the land was not, and the chlorophyll in its cells formed normally.

But if the dose was doubled lead, and selenium were powerless: because of too large amount of lead in plants not only became abnormal chloroplasts, but also mitochondria and the entire cytoplasm.

In an article in the Journal of Plant Physiology , the authors write that, and selenium and lead affect the meristem is a special plant tissue from which new cells are formed – but they are at it the opposite way. Selenium, even at low concentrations, stimulates the development of stand photosynthetic cells and plants in General. Lead also prevents the precursors of photosynthetic cells to develop properly, causing the whole plant in General grows worse.

If we talk about specific numbers, then selenium can compensate for the “lead” development defects if the concentration of lead is up to 50 mg per 100 g of soil. Although the experiments were made on wheat, the same effect and lead, and selenium, most likely, can be seen in other plants.

According to the press service of ITEB RAS.

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