Why is that certain mutants so useful to reseachers who investigate the regulation of plant development.?

Answer 1

A. Mutant phenotypes provide information about the biological role of the gene product in an organismal or cellular context (in vivo) by providing information concerning what goes wrong when the product does not function properly.

* A cloned gene can provide biochemical information about its product (enzyme, transcription factor, structural protein).
Mutants are generated by exposing a population of organisms to a mutagen and allowing the individuals in the population to reproduce.
mutagens = irradiation (UV, Xray, fast neutron, etc.), chemicals (ethyl methane sulfonate, nitrosoguanidine etc.), insertional elements (transposons, TDNA)

The mutagen induces multiple mutations in the genome of the cells exposed (M1 generation; mutations are heterozygous in diploids).
--Those mutations in germline cells are passed on to the next generation (M2 generation).
--In plant species that self fertilize (eg. Arabidopsis) the M2 population will include some plants homozygous for mutations.

Therefore: The M2 generation is typically screened for mutant phenotypes




Researchers need both phenotypic and biochemical information about their gene to understand its role.

The identification of a gene by mutant phenotype = forward genetics.

Using a cloned gene to find a mutant phenotype = reverse genetics

Answer 2

Mutant plants tell us about the physiology of plants. Some pea plants are dwarf. If we spray them with the hormone giberellin, some dwarf varieties will grow to normal height: other dwarf varieties will not. Those that do respond to gibberellin are usually mutants in gibberellin biosynthesis.