Abstract:
Plant hormones are of vital importance to the normal growth and development of plants. An important group of hormones, the cytokinins, is involved the process such as cell division, senescence, chloroplast, maturation, cotyledon expansion and morphogenesis of shoots and roots. Like other hormonal groups, little is known about the precise function, biosynthesis and mechanism of action of cytokinins. .The characterization of mutants blocked in some steps of cytokinin biosynthesis or action is a promising genetic approach to the study of these hormones. However, there has been only one report of a cytokinin mutant among higher plants. Present two year project was therefore initiated to systematically isolate and characterize cytokinin mutants of Arabidopsis, a convenient plant for mutagenesis study.
During the project, about 24 cytokinin resistant mutants of Arabidopsis thaliana have been isolated. Most abnormalities such as root hair abnormalities, altered gravitropic response, longer hypocotyls, dwarf or semi dwarf structure, frequent inflorescence braches, reduced apical dominance, and absence of trichomes and abnormalities of reproductive structures. Genetic studies have indicated single recessive nuclear mutations controlling the mutant phenotypes.
Present cytokinin resistant mutants have revealed several novel development processes that could be regulated by cytokinins. These mutants are expected provide useful tools to study cytokinins biosynthesis and their mode of action. They can further be used for isolation and potentially useful genes and their transfer to crop plants.
