Drought Tolerance Enhancement with Co-Overexpression of DREB2A and APX in Indica Rice (Oryza sativa L.) ()
ABSTRACT
Rice is a major cereal crop providing food
and energy to more than half of world’s population and drought is a challenging
abiotic stress limiting rice production. Engineering drought tolerance trait is a major
bottle neck because of multigenic control and complex nature. Two promising
candidate genes utilized in engineering drought tolerance include DREB2A
transcription factor (a master regulator of downstream stress inducible genes)
and APX (an important ROS scavenging enzyme). Overexpression of DREB genes has shown encouraging results
but with a negative impact on plant morphology and production. Moreover,
co-expression of DREB2A and APX genes’ influence on drought stress has not been studied. Hence, in the present
study, overexpression of single genes DREB2A or APX and co-expression of these genes
were studied for enhancement of drought tolerance in indica rice. Both genes
under control of CaMV 35S promoter were transferred by Agrobacterium transformation into rice variety BPT5204 popular for
slender grains in South India. Confirmation of T-DNA integration into rice
genome was done with PCR analysis of transgenes. Homozygous transgenic lines of
DREB2A, APX and DREB2A-APX generated in T3 generation were evaluated for drought tolerance during seed germination,
vegetative and reproductive stages. In seed germination stage, transgenic lines
exhibited higher germination rates on 200 mM mannitol MS medium in comparison to WT. In vegetative stage,
with-holding water for 7 days transgenic lines exhibited higher chlorophyll,
proline, reducing sugars and enhanced activities of APX, SOD and catalase
enzymes as well as reduced MDA content. The qRT-PCR analysis revealed higher
relative transgene expression under drought stress. In reproductive stage,
before maturity with-holding water for 7 days and restoring normal conditions, transgenic lines
developed longer panicles and a higher number of grains/plant
compared to WT. The overall results indicate that co-expression of
DREB2A and APX can provide enhanced drought tolerance in rice plants to combat
climate change conditions.
Share and Cite:
Sandhya, J. , Ashwini, T. , Manisha, R. , Vinodha, M. and Srinivas, A. (2021) Drought Tolerance Enhancement with Co-Overexpression of DREB2A and APX in Indica Rice (
Oryza sativa L.).
American Journal of Plant Sciences,
12, 234-258. doi:
10.4236/ajps.2021.122014.