Genetic regulation of phase change in Arabidopsis
Abstract
Higher organisms progress through a series of phases during development. In plants, the shoot progresses through a juvenile phase and an adult phase and ultimately produces reproductive structures. The transition from juvenile vegetative to adult vegetative development, a process known as phase change or shoot maturation, is marked by changes in morphology, anatomy, and physiology of the vegetative structures produced by the shoot. The duration of each phase directly impacts the morphology of plants because organs produced at different times are located at different positions along the shoot. Although phase change has been studied extensively in woody species, the regulation of this process remains poorly understood. Recently, phase change has been studied in the more genetically tractable herbaceous species maize and Arabidopsis thaliana. In Arabidopsis, the leaves developed along the shoot axis can be distinguished by a number of morphological characteristics. The first leaves produced are small and round with smooth margins, while leaves produced later are larger, more elongated and have serrated margins. Trichome distribution has a phase specific pattern in that leaves produced early in shoot development have trichomes only on their adaxial surface, while leaves produced later have trichomes on both the adaxial and abaxial surfaces. Application of gibberellic acid (GA) accelerates the development of abaxial trichomes. The development of abaxial trichomes is delayed in GA deficient ga1-3 plants. Several mutants were isolated in a screen for precocious abaxial trichome development. Mutations in the gene EARLY TRICHOMES cause plants to produce abaxial trichomes beginning with leaf one. The ert phenotype appears to be the result of adaxial characteristics being expressed on the abaxial side of the leaf, rather than the acceleration of phase change. Mutations in HASTY also accelerate the development of abaxial trichomes. In addition, hst plants have upward rolled leaves, greatly reduced pollen production, and retarded root development. HASTY was cloned using a positional cloning strategy and is predicted to encode a 1202aa protein with similarity to members of the importin β family of proteins. ^
Subject Area
Biology, Genetics
Recommended Citation
Krista M Bollman,
"Genetic regulation of phase change in Arabidopsis"
(January 1, 2001).
Dissertations available from ProQuest.
Paper AAI3003599.
http://repository.upenn.edu/dissertations/AAI3003599
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