Housekeeping enzymes, such as those involved in
nucleotide metabolism, are often thought to be expressed
at a consistent level in all cells. However, it is now evident
that activities of constitutively expressed genes are very
dynamic so as to meet the metabolic demands of plant
cells. Since these changes can have a profound effect on
plant development there is a new appreciation of the
importance of housekeeping activities in plant survival
such as in response to stress.
insertions and the development of tilling, a PCR-based
screening procedure to recover chemically-induced
mutants , are valuable resources for
the genetic analysis of these genes.