The phytohormone abscisic acid (ABA) plays a critical role in plant growth, development, and adaptation to various stress conditions. The cellular ABA level is constantly adjusted to respond to changing physiological and environmental conditions. To date, the mechanisms for fine-tuning ABA levels remain elusive. Here, we report that BGLU10, a member of a multigene family of β-glucosidases, contributes to drought tolerance in Arabidopsis. The T-DNA insertion mutant bglu10 exhibited a droughtsensitive phenotype, characterized by an increased rate of water loss, and lower leaf temperature, β-glucosidase activity, ABA content, and expressions of ABA-and drought-responsive genes under drought stress. In contrast, lines overexpressing BGLU10 showed greater drought resistance than that of the wild-type, as shown by decreased water loss via transpiration, higher β-glucosidase activity, ABA level, and expressions of ABA- and stress-responsive genes under drought stress. Transient expression of BGLU10::GFP and γ-TIP1::RFP in mesophyll cell protoplasts showed that the BGLU10 enzyme protein was localized to the vacuole. Meanwhile, BGLU10 was expressed in various organs, and was induced by several abiotic stresses, suggesting that BGLU10 may be involved in a variety of stress responses, and that hydrolysis of ABA-GE produces free ABA in the plant stress response.
WANG PengTao LIU Hao HUA HongJie WANG Lei SONG Chun-Peng
In order to investigate the mechanism of ROS signaling transduction in after-germination process, we screened a hydrogen peroxide sensitive mutant from EMS mutant library of Arabidopsis thaliana. Hydrogen peroxide sensitive 12（hps12）was screened from this library. Phenotype analysis indicated that hps12 had dwarf plant and shorter pod than wild type（WT）. The cotyledon greening rate of hps12 was decreased after being treated with 4 mmol/L H_2O_2. Furthermore, the isolated leaves of hps12 mutants showed more obvious symptoms of senescence than WT under the treatment of 10 mmol/L H_2O_2. Genetic analysis suggested that hps12 was a monogenic recessive mutant.
