Transplastomic plant

Plastid examples

A transplastomic plant is a genetically modified plant in which genes are inactivated, modified or new foreign genes are inserted into the DNA of plastids like the chloroplast instead of nuclear DNA.

Currently, the majority of transplastomic plants are a result of chloroplast manipulation due to poor expression in other plastids.[1] However, the technique has been successfully applied to the chromoplasts of tomatoes.[2]

Chloroplasts in plants are thought to have originated from an engulfing event of a photosynthetic bacteria (cyanobacterial ancestor) by a eukaryote.[3] There are many advantages to chloroplast DNA manipulation because of its bacterial origin. For example, the ability to introduce multiple genes (operons) in a single step instead of many steps and the simultaneous expression of many genes with its bacterial gene expression system.[4] Other advantages include the ability to obtain organic products like proteins at a high concentration and the fact that production of these products will not be affected by epigenetic regulation.[5]

The reason for product synthesis at high concentrations is because a single plant cell can potentially carry up to 100 chloroplasts. If all these plastids are transformed, all of them can express the introduced foreign genes.[1] This is may be advantageous compared to transformation of the nucleus, because the nucleus typically contains only one or two copies of the gene.[1]

The advantages provided by chloroplast DNA manipulation has seen growing interest into this field of research and development, particularly in agricultural and pharmaceutical applications.[5] However, there are some limitations in chloroplast DNA manipulation, such as the inability to manipulate cereal crop DNA material and poor expression of foreign DNA in non- green plastids as mentioned before.[5] In addition, the lack of post- translational modification capability like glycosylation in plastids may make some human- related protein expression difficult.[6] Nevertheless, much progress has been made into plant transplastomics, for example, the production of edible vaccines for Tetanus by using a transplastomic tobacco plant.[7]

  1. ^ a b c Rigano MM, Scotti N, Cardi T (2012-11-24). "Unsolved problems in plastid transformation". Bioengineered. 3 (6): 329–33. doi:10.4161/bioe.21452. PMC 3489708. PMID 22892591.
  2. ^ Ruf, S.; Hermann, M.; Berger, I.; Carrer, H.; Bock, R. (2001). "Stable genetic transformation of tomato plastids and expression of a foreign protein in fruit". Nature Biotechnology. 19 (9): 870–875. doi:10.1038/nbt0901-870. PMID 11533648. S2CID 39724384.
  3. ^ Raven JA, Allen JF (2003). "Genomics and chloroplast evolution: what did cyanobacteria do for plants?". Genome Biology. 4 (3): 209. doi:10.1186/gb-2003-4-3-209. PMC 153454. PMID 12620099.
  4. ^ Adem M, Beyene D, Feyissa T (2017-04-01). "Recent achievements obtained by chloroplast transformation". Plant Methods. 13 (1): 30. doi:10.1186/s13007-017-0179-1. PMC 5395794. PMID 28428810.
  5. ^ a b c Ahmad N, Michoux F, Lössl AG, Nixon PJ (November 2016). "Challenges and perspectives in commercializing plastid transformation technology". Journal of Experimental Botany. 67 (21): 5945–5960. doi:10.1093/jxb/erw360. hdl:10044/1/41455. PMID 27697788.
  6. ^ Faye, L.; Daniell, H. (2006-01-19). "Novel pathways for glycoprotein import into chloroplasts". Plant Biotechnology Journal. 4 (3): 275–279. doi:10.1111/j.1467-7652.2006.00188.x. ISSN 1467-7644. PMID 17147633.
  7. ^ Tregoning J, Maliga P, Dougan G, Nixon PJ (April 2004). "New advances in the production of edible plant vaccines: chloroplast expression of a tetanus vaccine antigen, TetC". Phytochemistry. 65 (8): 989–94. Bibcode:2004PChem..65..989T. doi:10.1016/j.phytochem.2004.03.004. PMID 15110679.