the Hormonal control of speed and a growth direction. tsitokininy

you are: the Hormonal control of speed and a growth direction

Above we already mentioned that cell fission in culture of a vegetative fabric depends from auksina and other factors of cellular division named tsitokintsnami. The Same control mechanisms operate, possibly, at regulation of division and growth of cages and in other parts of a growing plant, for example in lateral kidneys.

Opening tsitokininov has been connected with attempts to induce division of the certain vegetative cages which are grown up in culture. One of such attempts, undertaken in the early forties, consisted in allocation not impregnated jajtsekletki from zavjazi and its cultivation in the certain environment for the purpose of reception gaploidnyh germs. this purpose has not been reached. However it has been established that growth of very young normal germs is stimulated at addition by Wednesday of milk of a coconut (liquid endosperma huge seeds of a coconut palm tree). As no combinations known then factors of growth gave such result, it was clear that coconut milk contains any substance (or substances), responsible for this unique effect. Therefore some researchers have undertaken attempts to allocate from milk of a coconut and to characterise hypothetical factors of cellular division.

In opening tsitokininov have resulted experiences of Skuga and its employees from Viskonsinsky university in which they tried to induce division mature serdtsevinnyh tobacco cages. In intaktnyh plants these cages increase in sizes, but never share. However at replacing to the Wednesday containing auksin and milk of a coconut, they start to share. Testing different connections, group Skuga has found out that adenin at presence auksina possesses some activity stimulating cellular division. Subsequently nucleinic acids into which structure enters adenin have been checked up also. As a result it has been established that DNA containing in one old sample of sperm of a herring, has yielded the results, quantitatively surpassing what have been received with adeninom. It was found out Later that any sample of DNA or even one adenozina can be transformed into extremely active material, if avtoklavirovat it in corresponding conditions. The new substance formed in such unusual conditions, has been allocated and identified as 6-furfurilade-nin. Because of its high activity at indutsirovanii cellular division (tsitokineza) in a tobacco core (at presence auksina) this substance has been named kinetinom.

After a nature establishment kinetina researchers could be engaged in searches in plants of other similar materials. It has appeared that unripe fruits and developing grains of cereals are rich sources of the activity stimulating cellular division. Finally from developing grains of corn the substance named zeatinom (fig. 9.27) which on the structure reminded kinetin has been allocated. This substance and closely related connection izopenteniladenin are found out now in all checked up plants. Such connections which have received the general name tsitokininy, are usually connected with ribozoj (ribozidy) or with ribozoj and phosphate (ri-botidy). It is established that stimulating activity of milk of a coconut is caused by action of a mix of many connections among which tsitokinin has been identified as zeatin-ribozid. In scientific researches are widely used synthetic tsitokininy, such as kinetin and benziladenin as the is more active natural tsitokininy, the it is more difficult to receive them.

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