Phenotypic analysis of Arabidopsis mutants: hypocotyl length.

INTRODUCTIONHypocotyl elongation of young seedlings is an important response affected by both endogenous developmental programs and exogenous signals, such as light quality and quantity. When a seed germinates in the dark (as it might if it were buried in soil), the hypocotyl extends and the cotyledons remain folded under a protective hook. When the seedling reaches the light, the rate of hypocotyl elongation is inhibited, and vegetative development is initiated. This protocol describes the measurement of hypocotyl lengths in freshly germinated seedlings.