Gene function

One of the reasons scientists study inheritance and DNA sequences is to discover the function of genes. What makes some varieties behave differently than others? For example, if one maize variety is resistant to a particular pathogen, and also shows a difference in DNA sequence at a particular gene, this gene could be the cause of this resistance. Of course, an organism has tens of thousands of genes and most likely there is more than one gene affecting any particular characteristic. These traits are called “quantitative” – many genes working together to affect one characteristic, as opposed to “simple” or Mendelian traits that are controlled by only one or two genes.

An example of a quantitative trait that is currently being studies by maize scientists is flowering time. Some maize varieties flower earlier (and so mature faster) than others, and it is one way that they adapt to their environment, as day length is different among geographic latitudes. Scientists have discovered that flowering time is a very complex trait, regulated by many genes of small effect: Quantitative Trait Loci, or QTL.

The Genetic Architecture of Maize Flowering Time
Edward S. Buckler, et al. Science 325, 714 (2009); DOI: 10.1126/science.1174276