Phenotypic Analysis: Messages from Biology

Phenotype is the message we get that tells us that there has been a change in a gene controlling some biological function.  What we learn from the phenotype actually depends on our ability to recognize and properly interpret what we observe.  In the simplest case it is the presence or absence of a measurable product (anthocyanin) or structure (ligule). In actual fact there are many functions involved in production of a particular product or activity and these are all a part of a complicated choreography leading to a certain diplay. Maize is an exceptionally well suited organism for demonstrating this point.  We have produced and have access to a unique large collection of several thousand mutants induced by EMS, transposons, radiation and of spontaneous origin.  All are currently kept in an extensive “Mutants Data Base” with high resolution photo images and pertinent information.  A duplicate copy of most of these files with images and data is also kept at MaizeGDB.  This presentation will use three mutant gene systems to demonstrate the intricate relationships involved in going to and from a gene and a recognizable phenotype:

(1)  dek1 (clf1) EMS induced recessive mutant and an Ac-Ds transposon analysis.

(2)  PgD EMS induced dominant chimera case.

(3)  Les  Disease Lesion Mimic; Programed Senescence.

In reviewing this material it is quite clear that there are many important genetically controlled activities that regulate expression of a phenotype without being in the biochemical pathway that leads to the observed product.