Mendel’s Genes: Toward a Full Molecular Characterization

Abstract

The discipline of classical genetics is founded on the hereditary behavior of the seven genes studied by Gregor Mendel. The advent of molecular techniques has unveiled much about the identity of these genes. To date, four genes have been sequenced: A (flower color), LE (stem length), I (cotyledon color), and R (seed shape). Two of the other three genes, GP (pod color) and FA (fasciation), are amenable to candidate gene approaches on the basis of their function, linkage relationships, and synteny between the pea and Medicago genomes. However, even the gene (locus) identity is not known for certain for the seventh character, the pod form, although it is probably V. While the nature of the mutations used by Mendel cannot be determined with certainty, on the basis of the varieties available in Europe in the 1850s, we can speculate on their nature. It turns out that these mutations are attributable to a range of causes-from simple base substitutions and changes to splice sites to the insertion of a transposon-like element. These findings provide a fascinating connection between Mendelian genetics and molecular biology that can be used very effectively in teaching new generations of geneticists. Mendel's characters also provide novel insights into the nature of the genes responsible for characteristics of agronomic and consumer importance.

MOLECULAR BASIS OF THE DWARFISM CHARACTER IN CULTIVATED PLANTS. I. GROWTH DISTORTIONS DUE TO MUTATIONS OF GIBBERELLIN METABOLISM AND SIGNALING (review)

“…As GA is accumulated, the GA 20 -oxidase gene expression is reduced, and GA catabolism gene expression is enhanced [38][39][40]. In the mutant dwarf pea plants (le) [21,22] with a lack of GA due to reduced function of C3,β-oxidases the transcriptional activity of GA biosynthesis gene (GA20ox) is high, while it is low for GA deactivation gene (GA2ox). In the pea mutants SLN (SLENDER) with elongated shoots the disorders affect C2,β-oxidase gene.…”

Legumes’ contributions to genetic research, a historical perspective from Mendelism up to massive sequencing

“…There are other candidate genes for characters in the pea genome, nonetheless still no solid evidence exists to say which of the alternative genes Mendel could have used in each particular case. A more complete review of these genes and other aspects of Mendel's work can be found in Ellis et al (2011) and Reid and Ross (2011).…”

Pea (Pisum sativum L.) in biology prior and after Mendel's discovery

“…However, given that his research built on the previous work of others and that we have some historical accounts of what mutants were available at the outset of his experiments in the 1850s (e.g., Knight 1799), we can make an educated guess in most instances (Reid & Ross 2011). Even harder than defining which seven loci Mendel studied is the question of which mutations he used.…”

“…Theoretically, it is now quite clear that there are many possible mutations in each gene that could produce the same phenotype, especially if Mendel's original mutation was a null. Again, the only way of determining this is to see what material would have been available in central Europe at the time that Mendel performed the studies (Reid & Ross 2011). With the improved linkage maps available today the seven traits in fact are thought to occupy only five of the seven linkage groups.…”

“…Certainly Mendel would be surprised by the phenomenon of linkage. It appears that an element of luck was involved with his choice of characters, which are either not linked or, if linked (as may have been the case with the stem length and pod form characters), possibly not subject to a detailed dihybrid analysis by Mendel (Ellis et al 2011;Reid & Ross 2011).…”