| The abiotic stresses including drought and salt stress, aluminum toxity in acid soil and so forth, are the major problems that affect the growth of plants and the productivity of crops adversely. Now, investigating the molecular mechanisms of plants in response to abiotic stress, screening resistance genes and enhancing tolerance of crops to stresses, have been one of the leading subjects worldwide.The water deficit caused by drought or other stress is the most pervasive and damage for agriculture among the abiotic stresses. The adaptive responses of plants to such stresses can be conceptually grouped:the direct osmotic signal to regulate water balance and confer osmoprotection, that is through ABA dependent or independent pathways; the indirect signal for basic defense in stress damage control and repair, detoxification; and signal for growth regulation.In this study, we found the Arabidopsis WRKY46encoding a trancription factor, could fast responde to drought, salt as well as peroxide hydrogen, and its transcripts arrived at high level in30minutes. The expression pattern analysis revealed that WRKY46is mainly expressed in roots. We further observed the phenotypes of WRKY46T-DNA insertion mutants and found that wrky46mutants were more sensitive to NaCl and mannitol compared with the wild type Col-0, for the mutants had a worse shoot growth under treatment. Microarray analysis showed that146genes were up regulated in WRKY46overexpression line (OV46), while151genes were down regulated without treatment; when under dehydration condition, there were212and102genes up and down regulated in OV46line respectively. Among the up-regulated genes, there were64%and50%genes respectively, that could responde to drought, salt or osmotic stresses. Particularly, about45%of these genes were also responsive to oxidative stress. We can speculated that WRKY46is mainly involved in cellular redox and ROS homeostasis to control the oxidative damage caused by drought and salt stress. |
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