The flower of Crinum latifolium with 12 petals,12 stamens & 2 stigmas: To start with every organism has fixed number of chromosomes in each cell of the body, which in deploid organisms we call 2n (two sets of ) chromosomes. During sexual reproduction when gametes are formed the two sets seperate , thus the gametes have only one set of chromosomes, n. When the two gametes fuse (like pollen grain and ovule , or sperm with ovum) we again get a deploid cell (n+n=2n) called zygote. This after repeated cell division and organ formation form the individual. plant or animal. That is how we get half chromosomes from father and half from mother.
Every new cell formed here after cell division is deploid. And then we say race continues.
During the cell division every chromosome is attached to a spindle by a fibre called spindle fibre. This pulls the chromosome to pole when the chromosomes are in dividing state.
If the chromosome fails to attach to the fibre it fails to get incarporated in new cells formed, either gamete or normal body cell. thus cells produced are abnormal because they miss one or more chromosomes.
Sometimes the chromosomes in deviding state fail to detach from one another and the whole lot go to one cell while the other cell gets nothing. the one which gets nothing perishes, while the one get both sets is now abnormal gamete having 2n number of chromosomes instead of n. When this gamete fuses with other gamete of n type the zygote gets 3n which is called as polyploid.
this can happen in the body cells also. like in plants when the cells are dividing during growth the chromosomes duplicate in each cell and seperate into half. so each cell gets 2n. But sometimes if the duplicated chromosomes are not seperated, -abnormal- then the resulting cell gets 4n because chromosomes are already duplicated. such cell when form further cells they all will have 4n chromosomes. polyploid cell from where new shoot formed will be polyploid.
many a times it may result into triploi–3n, tetraploid–4n, pentaploid–5n, hexaploid–6n, hectaploid7n, octaploid 8n ect.
polyploi result into gigantism that is big flowers, leaves etc.
when this occurs naturaly it is seen as what is seen in your Lily flowers.
This phenomenon is called as chromosome abberation
pl search googal for elustrations.
Dear Botanists and Zoologists pl forgive me for the use of crude language and avoiding the bumbarding words.
This is related to earlier discussion – https://groups.google.com/forum/#!msg/indiantreepix/7-kRSVOxAMQ/sDatK69AGYAJ and part thereof – https://groups.google.com/forum/?hl=en#!topic/indiantreepix/WacK5j7fs1g.
It seems to me that two flowers (Crinum latifolium) fused together!
Polyploidy, as had been explained in the above threads?
Or, was it mutation in normal diploid cells?
I tried to find…. but….
Polyploidy can result various alterations –
Very tough for a layman –
Can anybody please explain in simpler terms?
Thanks for the query.
First when the word Mutation got coined it was for the modification of similar nature in plant Oenothera lamarkiana. In this the leaves and flowers of the plant was suddenly observed to be larger on one branch of the plant. There was no indication of such change prior when it was visible. Hence Hugo de varies called it as Mutation which means sudden change without any indication in the previous generation.
Latter when the structure of gene was studied and is known the changes which occur at gene level are called as Mutation. While the changes which occur in numerical form or structural form of chromosomes are called as chromosomal aberrations.
Accordingly the actual discovery of mutation also was turned out to be chromosomal aberration. When the change occurs at gene level it is called as mutation. eg diseases like Thalasemia, hole in the septum of heart, or such are examples of point mutations. Not able to recollect the examples in plants. But if such changes occur in the reproductive cells/germinal cells they are passed to the gametes and then to the next generation. But if the changes occur in somatic cells then they are not passed to future generation.
Thus after the discovery of genes the chromosomal aberrations and the mutations are differentiated. The polyploidy thus falls under Chromosomal aberrations.
Thank you very much for this elaborate lesson on mutation and chromosomal aberration.
Since the flower in https://groups.google.com/forum/#!msg/indiantreepix/7-kRSVOxAMQ/sDatK69AGYAJ had not been resulted out of sacrificing stamens (as have been explained in https://en.wikipedia.org/wiki/Double-flowered#Genetics_of_double-flower_mutations), i think the abnormality lies in tissue differentiation due to certain changes in gene expressions, rather than a polyploidy condition.
Thank you so much for making me think.
Ok now our flowers of Crinum. Basically as you have observed the stamens are not sacrificed. But if you recollect Crinum has 6 petals and 6 stamens. In our flower the way petals are doubled even stamens are also doubled. They are 12 in number. Hence it is the case of Polyploidy.
I forgot to mention one part, such aberrations can occur naturally as well as can be created artificially. The tissue culture in artificial hybridization plays a important part.
Thank you very much for explaining the reason behind the double flower in Crinum.
I understand now that it is a case of polyploidy, not an abnormality in tissue differentiation, as i thought earlier.
I wonder if this expression of polyploidy condition was confined only in flowers of that particular plant or the plant had every part in double dose.
Wiki informs animal world also have polyploidy conditions. Is “polydactyl” such a phenomenon?