Physiological Mechanism and Gene Expression Profile Analysis in Mitogen-Activated Protein Kinase (OsMAPK3)ver-expression Transgenic Rice (Oryza sativa L.) nder Drought and Salt Stresses
Date Issued
2009
Date
2009
Author(s)
Chang, Chia-Ling
Abstract
Drought and salt stresses can affect rice growth and productivity. It is important to understand the mechanism and develop drought and salt tolerant rice. Previous study showed that overexpression of OsMAPK3 (Mitogen-Activated Protein Kinase) in rice can increase its stress tolerance. However, the detail action and mechanism remains to be solved. To further reveal the role of OsMAPK3 in rice drought and salt stress tolerance, in this study we conducted molecular characterization, physiology, microarray and real-time PCR analysis in OsMAPK3 overexpression transgenic rice. First, we determined transgene integration site and identified homozygous OsMAPK3 line. Then, in vivo H2O2 fluorescence staining image indicated that the amount of H2O2 in transgenic rice was lower then that of wild type under stress. Under normal growth conditions, the OsMAPK3 overexpressing rice displayed higher photosynthesis rate, stomata conductance and water use efficiency (WUE). By comparison of gene expression profile difference between transgenic and non-transgenic rice with microarray, we were able to confirm that several abiotic-stress related genes that known to increase drought and salt tolerance had already been induced in transgenic rice. These genes included osmolyte-adjustment related gene TPPA, antioxidative enzymes related gene GR1, GR3, CatA and CatC, drought and salt induced transcription factors OsDREB1B, OsDREB2A, OsMyb4, OsZFP252 and OsNAC6, ion channel related protein ClC-a, NHX and downstream drought responsive gene DHN1 etc. In addition, the OsMAPK3 transgenic rice was hypersensitive to ABA with lower seeds germination rate. Under normal growth, OsMAPK3 transgenic rice contains higher content of endogenous ABA and increased gene expression of ABA-responsive gene OsRab16A. This result indicated that OsMAPK3 may participate in ABA biosynthesis or signal transduction pathway then alter the sensitivity of transgenic rice to ABA. Taken together, overexpression of OsMAPK3 in rice could increase its drought and salt stress tolerance because of higher antioxidant activity, photosynthesis and water use efficiency, induction of stress-related gene expression and alteration of ABA sensitivy.
Subjects
abiotic stress
transgenic rice
Type
thesis
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