Function Analysis Of An Arabidopsis Thaliana Small GTP-binding Protein RabD2b

As important swithes in cell signal transduction, the small GTPase are highly conserved in all organisms. Their interacting with various regulators and effectors generate diversity functions. The material used in this study was small GTPase RabD2b gene whose expression in old leaves is remarkably increased in gene chip. In order to validate the function of RabD2b gene, we observate T-DNA insertions, over expression RabD2b gene transgenic lines and wild type about there growth; use x-Gluc to dyeing RabD2bPro-GUS transgenic plants and treat growing plants under stress to measure there expression. The main results are as follows:1. Northern analysis confirmed that the expression in old leaves, bud and flower were higher than other organisms, especially in old leaves and flower, the expression were greatly increased. And the expression also increased under drought, salt, exogenous ABA and JA stress.2. Over expression transgenic plants exhibit delaying senescence relative to wild type whereas insertions grow more rapidly and flower earlier than wild type plants through observation to T-DNA insertions and over expression plants.3. We also identified that insertions show nonsensitive to ABA compared to wild type whereas over expression exhibit hypersensitive to ABA with seeds germination experiment. RabD2b gene may be a positive regulator of ABA signal transduction.4. GUS activity only in the two-week old T1 generation transgenic plant senescing cotyledon but activity in all organisms under ABA stress, meanwhile, the GUS expression increased.The role RabD2b gene in plant growth and development or abscisic acid positive regulation in signal transduction provide new opportunities both to the study of ABA regulation and to the research functional improvement of Rab GTPase.