Sir please get the paper in attachment and hopefully this paper will help you regarding to this...

Dear Mr. Chandra: Thanks for sending me a paper by Stencil, A. and B. Cresp. 2013. What is a genome? Molecular Ecology 22: 3437-3443. This is a very good paper. I would recommend every biologist, particularly students, to read it.

Thank you sir ... Its my pleasure....

If it's nucleic acid and in the cell and is inherited, yes it is genetic material.

Dear Dr. Lavett: Thank you for your participation.

Dear Dr. Farook: Thanks for attaching a very interesting article Case, M.E., M. Schweizer, S.R. Kushner and N.H. Giles. 1979. Efficient transformation of Neurospora crassa by utilizing hybrid plasmid DNA. PNAS 76(10): 5293-63. I recommend others to read it. I also recommend an older paper Mishra, N.C. 1976. Episome-like bahaviour of donor DNA in transformed strains of Neurospora crassa. Nature 264(5583): 251-3.

In response to my question dated Mar 28, 2014 “Should plasmid nucleic acid be considered genetic material? “, Prakash Chandra of G. B. Pant University of Agriculture and Technology, Pantnagar, India referred me to a decent paper by Stencil and Cresp (2013).

According to Stencel and Crespi (2013), an evolutionary genome represents a set of genetic material, in a lineage, that due to common interests tends to favor the same or similar phenotypes. There is lack of consensus concerning the meaning of the term ‘genome’ and suggest an evolutionary conceptualization of this idea that parallels the evolutionary idea of a ‘gene’ developed by George C. Williams. Hans Winkler in 1920 developed term ‘genome’ via merging of ‘gene’ with ‘chromosome’ Currently, the term is defined, for example, as ‘the entire genetic complement of a living organism’ (Brown 2007), all DNA in the chromosomes of a eukaryote, all DNA in the chromosome of prokaryotes, or all DNA or RNA in a virus (Lederberg and McCray 2001).

Zilber-Rosenberg and Rosenberg (2008) point out ambiguity in concept of genome. Do we include nonchromosomal genetic material (such as cytoplasmic elements that harbor their own DNA) or elements in chromosomal DNA that are independently mobile. Should any entity to be considered genome be vertically inherited? Second, is the genome a property of a cell, an individual, a population, a species or all of these? Similarly, definition of gene is not yet final.

Stencel and Crespi (2013) suggest that an evolutionary genome may be conceptualized as: ‘A set of genetic material, in a lineage, that due to a sufficient degree of vertical inheritance and other factors favoring cooperation among genes, tends to favor a common or broadly overlapping suite of phenotypes’. Whereas a gene represents a functional ‘replicator’, a genome codes for producing a functional ‘vehicle’ of selection. Among prokaryotes, the shared reproductive interests of linked, chromosomal DNA, co-inherited over many generations, is expected to favor cooperation among genetic elements in the cell. Extracellular genetic material, such as components of the microbiome, may influence levels of phenotypic adaptation either positively or negatively.

Diane K. Lavett of Emory University stated in response to my above question, “If it's nucleic acid and in the cell and is inherited, yes it is genetic material.

V. Adnaan Farook from University of Calicut, India opined “… I could understand the fact that plasmids can cause genetic transformations. …” He also suggested reading of a paper by Case et al. (1979). Transformation has been a well-established process for the transfer of genetic material in prokaryotes. Case et al. (1979) developed an efficient transformation system for Neurospora crassa that uses spheroplasts and pVK88 plasmid DNA. pVK88 contains the E. coli plasmid pBR322 as well as the N. crassa qa-2+ gene encoding catabolic dehydroquinase, an enzyme which is capable of substituting for biosynthetic dehydroquinase in either E. coli or N. crassa. With plasmid pVK88 DNA, it has been possible to transform a stable qa-2– mutant (M246) to qa-2+. These experiments show flexibility of prokaryotic plasmids to work efficiently in eukaryotes.

I also recommended to the readers an older paper by Mishra (1976). He finds that certain features of gene transfer in eukaryotes have similarities with bacterial transformation. The occurrence of inositol-independent (inl+) transformants has been reported in Neurospora when an inositol-requiring (inl–) mutant strain is treated with a wild-type DNA preparation. Although these transformants are stable for inositol independence (inl+) during the somatic cell cycle they differ in the ability to transmit this character to their sexual progeny. Essentially there are two groups of transformants, one capable of Mendelian transmission and another showing only a rare non-Mendelian transmission of the transformed character (inl+)). Such differences in modes of genetic transmission can be explained if the donor DNA exists as an episome in the transformed strains. Thus the physical status of the episomes determines the Mendelian and non-Mendelian transmission of the genetic character controlled by them. When integrated they are transmitted in a Mendelian way like any other chromosomal gene; whereas in the non-integrated (autonomous) form their nucleolytic degradation (or slow replication followed by segregation) during meiosis can lead to non-Mendelian transmission. This hypothesis is supported by demonstration of a continued aberrant transmission of the inositol independence to the sexual progeny in the subsequent generations.

To wind up the discussion on “Should plasmid nucleic acid be considered genetic material? “, let us first consider the properties that a piece of nucleic acid must have to be defined genetic material: it must (1) store and transmit biological information, (2) replicate, (3) undergo recombination, and (4) undergo mutation. Plasmids possess all these properties. Further, plasmid DNA, as discussed in the preceding paragraphs, have exhibited their ability to cause transformation in prokaryotes as well as eukaryotes.

Thus plasmid nucleic acids clearly qualify to be called genetic material.

References

Case, M.E., M. Schweizer, S.R. Kushner and N.H. Giles. 1979. Efficient transformation of Neurospora crassa by utilizing hybrid plasmid DNA. Proc. Natl. Acad. Sci. USA 76 (10): 5259-63.

Mishra, N.C. 1976. Episome-like bahaviour of donor DNA in transformed strains of Neurospora crassa. Nature 264 (5583): 251-3.

Stencil, A. and B. Cresp. 2013. What is a genome? Molecular Ecology 22: 3437-43.

Lederberg, J. and A.T. McCray. 2001. ‘Ome sweet ‘omics: a genealogical treasury of words. The Scientist 15: 8.

Zilber-Rosenberg, I. and E. Rosenberg. 2008. Role of microorganisms in the evolution of animals and plants: the hologenome theory of evolution. FEMS Microbiol. Rev. 32: 723-35.