|Coyne, Clarice - Clare|
Submitted to: Trends in Plant Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/22/2011
Publication Date: 7/19/2011
Citation: Ellis, T.N., Hofer, J.M., Timmerman-Vaughan, G.M., Coyne, C.J., Hellens, R.P. 2011. Mendel, 150 years on. Trends in Plant Science. http://dx.doi.org/10.1016/j.tplants.2011.06.006. Interpretive Summary: Mendel’s paper “Versuche über Pflanzen-Hybriden” is the best known in a series of studies published in the late 18th and 19th centuries that built our understanding of the mechanism of inheritance. The title of Mendel's paper is usually translated in English as “Experiments in Plant Hybridisation” which reflects the impact of his work for the science of genetics rather than Mendel’s own concern with the nature of hybrids and their implications for "Umwandlung einer Art in eine andere"; the transformation of one species into another. Another misconception is that Mendel's results and experimentation were in some way suspect; this derives from RA Fisher's attack on Mendelism. However, these defamatory criticisms have been roundly debunked. In his paper Mendel describes eight single gene characters of pea (Pisum sativum), but investigates the segregation of seven. The eighth to which he refers is the ‘purple podded’ character determined by the gene Pur on linkage group I. He also discusses the segregation of three traits (tall vs short, green vs yellow pods and inflated vs constricted pods) in common bean (Phaseolus vulgaris) that are likely orthologues of the corresponding characters he studied in pea.
Technical Abstract: Mendel’s paper “Versuche über Pflanzen-Hybriden” is the best known in a series of studies published in the late 18th and 19th centuries that built our understanding of the mechanism of inheritance. Mendel investigated the segregation of seven single gene characters of pea (Pisum sativum). Four of Mendel’s genes have been identified to date. These genes encode enzymes (R, Le), a regulator of the activity of a biochemical pathway (I) and a transcription factor (A). The known mutation types are: a transposon insertion (r), a splice variant (a), a mis-sense mutation (le-1) and an amino acid insertion (i). Genes for the three remaining characters (green vs yellow pods, inflated vs constricted pods, and axial vs terminal flowers) remain uncharacterised. This manuscript focuses on the identification of four of Mendel’s genes (R/r, round vs wrinkled seed; I/i, yellow vs green cotyledons; A/a, coloured vs unpigmented seed coats and flowers; and Le/le, long versus short internode length). In addition, the possible nature of the three other characters studied by Mendel (Gp/gp, green vs yellow pods; P/p or V/v, inflated vs constricted pods; and Fa/fa or Fas/fas, axial vs terminal flowers) is hypothesised. Three homologues of these transcription factor genes are located on chromosome 2 of M. truncatula in regions syntenic with P and V and are under investigation as candidates for P or V in pea.