What Is Polyploidy?-Definition And Levels Of Polyploidy

A normally diploid cell or organism develops one or more additional sets of chromosomes, a situation known as polyploidy. That is to say, the polyploid cell or organism has three or more times as many chromosomes as the haploid cell. When all of the chromosomes are not joined together during mitosis or meiosis, polyploidy results.

What Is Polyploidy?

The heritable state of having more than two complete sets of chromosomes is known as polyploidy. Plants frequently have polyploid DNA, as do several fish and amphibian species. For instance, some frogs, leeches, and salamanders are polyploid.

How Does An Organism Become Polyploid?

When a rare mitotic or meiotic calamity, such as nondisjunction, results in the formation of gametes with a full complement of duplicate chromosomes, the result is a polyploid. This process is frequently used to produce diploid gametes.

A triploid zygote is created when a diploid gamete combines with a haploid gamete, albeit these triploids are typically unstable and frequently sterile. A tetraploid zygote, which has the potential to be stable, is created when a diploid gamete combines with another diploid gamete.

Tetraploids (four sets of chromosomes), Hexaploids (six sets of chromosomes), and other chromosome-pair multiples are just a few of the various polyploid types that can be found in nature.

Levels Of Polyploidy

Various species show varying degrees of tolerance for polyploidy. For instance, flowering plants have a relatively high frequency of polyploids (1 per 100,000), which indicates that plants have a remarkable tolerance for polyploidy.

Some fish and frog species and this is also true. Higher vertebrates don’t seem to be able to survive polyploidy very well, and 10% of spontaneous abortions in people are thought to be brought on by polyploid zygotes.

What Is Polyploidization?

The inability of polyploids to interbreed with their diploid forebears typically makes polyploidization a sympatric speciation pathway.

Sequencing proved that this species descended from E. Roberts, a triploid sterile hybrid of E. Guttata and E. Lutea that had both been introduced and naturalized in the United Kingdom. Through genome duplication from local populations of E. Roberts, new populations of E. Peregrina emerged on the Scottish mainland and the Orkney Islands.

The lack of sterility in E. peregrine is caused by a rare genetic mutation.

Latest Research In Field Of Polyploidy

• Scientists have found that most green plant species, including crop and wild plants, are polyploid or have ancient polyploid signatures in their genomes. Polyploidy plays a significant role in plant evolution, driving genome and chromosome evolution. Mechanistic models are being developed to understand the impact of polyploidy on genome structure, gene function, and fertility. [1]
• Scientists revisited the occurrence of ancient polyploidy in leptosporangiate ferns using transcriptome data and statistical analyses. They identified four WGD events and emphasized the importance of accounting for uncertainties and conducting proper corrections in gene tree–species tree reconciliations. [2]
• Scientists studied the effects of zinc-oxide nanoparticles (ZnO-NPs) on polyploid and diploid rice lines exposed to cadmium (Cd) toxicity. ZnO-NPs improved plant growth and reduced Cd accumulation, with polyploid rice showing greater resistance. Gene expression analysis identified metal and sucrose transporter genes as being differentially expressed. [3]
• Scientists investigated post-polyploidization genome dynamics in a chromosomally stable lineage of Malvaceae endemic to New Zealand. They found that polyploidy led to concerted evolution and gene loss in the island lineages, despite chromosomal stasis. [4]