Ageing of plants, maturing of fruits and subsidence of leaves. Ageing of the whole plant

you are: Ageing of plants, maturing of fruits and subsidence of leaves

Till now we considered ageing tsvetkov, fruits and leaves, instead of ageing of the whole plant. Till now experimenters gave not enough attention to ageing of all plant as a whole. However that fact that this process is under any absolutely certain physiological control, speaks about necessity of its more careful studying. Think that, say, on wheaten fields of Kansas approximately at the same time after formation of seeds there is an ageing and dying off of millions plants! What reason of what these plants stop ability to live and die off, leaving after itself for a following season only seeds? Why long-living long-term kinds, for example such how an agave American, grow quickly to die off only for a long time after the termination of flowering and formation of fruits? At the plants blossoming only once, such as odnoletniki, the reproduction, apparently, causes inclusion of a series of the processes conducting to  destruction of the given plant. Removal tsvetkov or developing fruits frequently slows down or completely prevents ageing. As developing fruits and seeds demand large supplies of nutrients, the assumption has been come out that development of other part of a plant chokes because of the deficiency of nutrients resulting a competition between bodies of a plant. This theory has been denied, when researchers have found out, what even formation small man's tsvetkov on dvudomnom a spinach plant leads to ageing. As these man's tsvetki do not develop further and, hence, do not exhaust stocks of nutrients in a plant, the effect of ageing induced by them should be connected with any other mechanism.

One of genetic lines of peas forms tsvetki and fruits at a short bottom, but does not grow old until it will not transfer to conditions of long day. However in the absence of fruits long day does not cause ageing in these peas. As fruits develop completely at a short bottom and do not render on ageing any stimulating influence, it is impossible to explain ageing by a diet. Most likely occurs, possibly, any change in hormonal balance, so in the conditions of long day in a plant the insufficient quantity of a hormone preventing ageing is formed to neutralise any effect inducing ageing which fruits could cause. We know that at cultivation of the given line of peas at a short bottom ageing prevention is caused by transferring on a shank of substance of the unknown nature causing ageing. As peas of this line differ only one gene from peas at which ageing does not depend on length of day, the ageing control, probably, are carried out by a product of one gene, perhaps the enzyme regulating synthesis of any hormone.

Ageing both separate bodies, and the whole plant is connected with reduction of metabolic activity and decrease in speeds of synthesis RNK and the squirrel. We already spoke about changes in intensity of breath and permeability of the membranes accompanying maturing of a fruit. Action of the majority of the hormones which are slowing down ageing, at least is partially caused by that they support synthesis RNK and the squirrel. Ageing of a fabric of a fruit, for example, at beans chokes auksinom or tsitokininom. In one leaves ageing is slowed down under the influence of one tsitokinina whereas in others one is effective only gibberellin. Many researches show that ageing at plants represents not simply any slowed down and fading process, and any other stage previous it is faster the active physiological stage of life cycle as well regulated by hormones, as well as. The death of individual cages or fabrics in a plant can be the normal, controllable and localised event helping with creation of the definitive form of a plant. As an example it is possible to result  destruction of cages traheid and vessels of which are formed hollow, but effective cages of water spending system.

Since germination of seeds, the plant undergoes a series ontogeneticheskih changes, each of which is under the selective control of various sites of its genetic device. An induction and reprisal of certain genes vegetative hormones can operate, but all of us yet do not understand the nature of the main supervising system which programs an induction and reprisal of specific genetic activity. Even in mature, completely differentiated cages there is a full set of the genes containing all information, necessary for formation of the whole plant. This potential can be revealed, if certain mature cages to grow up in culture of fabrics where they as a result of stimulation dedifferentsirujutsja, start to share again and eventually give rise to the whole new plant. Experiment of this kind shows that maturing and ageing of cages do not grow out of loss of a genetic material. Most likely they, apparently, are caused by a number of changes in dynamics of synthesis of cellular fibers (or at least correlate with such changes). Hence, cage - ageing is result of the changed relative activity of various genes that leads to synthesis of insufficient quantity mrnk, necessary for maintenance of those functions which are important for integrity of a cage, and at the same time resolves synthesis of superfluous quantity various gidroliticheskih enzymes, such, as nukleazy and proteazy. Frequently ageing is accompanied also by change of permeability of membranes that causes infiltration of materials usually divided among themselves from one cellular kompartmenta in another. Especially it concerns to vakuoli which quite often contains toxic connections. They are allocated in cytoplasm if tonoplast proceeds, promoting the further ageing and death of a cage.