Research On The Regulatory Mechanism Of Zma-miR408 Under Drought Stress

Drought stress limits yield severely in agricultural production improvement.When the plants under drought stress,complex gene regulation mechanism is employed to response water deficiency.It is generally known that miRNAs play major roles in plant development and abiotic stress response.Mi R408,conserved in plants,targets copper related genes.Expression level of miR408 is significantly affected by a variety of developmental and environmental conditions,however,the biological function of miR408 is still unknown.To examine the miR408 function under drought stress,transgenic rice lines containing the STTM-zma-miR408 gene were created by transgenic technology in this study.The positive transgenic lines with STTM-miR408 were chosen for phenotypic analysis,as well as the expression levels of miR408 and its target genes through q RT-PCR.In order to explore the functional characterization of miR408,certain drought responsive genes identified by other researchers were also charactered using q RT-PCR.The main results are as follows:1)Short Tandem Target Mimic(STTM)were employed to constructs p CAMBIA3301::35s::STTM408,using the method of agrobacterium mediated rice transformation,and the corresponding positive transgenic lines were obtained.T0?T1?T2 generation positive test showed that the gene is inserted into the rice genome,and can be stable genetic.All these positive materials can be used to further research the function of mi408 in rice development,especially for rice stress response and so on.2)The phenotype and physiological and biochemical characters changes were identified after drought treated 15 days.with the down-regulate miR408's expression,We found that transgenic plants displayed morphological changes and exhibited decreased drought tolerance associated with reduced plant height,chlorophyll content and relative water retention,but increased Root length and promoted seed germination.3)Our results indicated that STTM-miR408 in rice can significantly suppression the expression levels of its target gene and the drought-responsive genes POD,SODA1,RD22 and b ZIP46,as well as the ABA synthetic gene ZEP1 were down-regulated in the down-regulate miR408's expression lines but the ABA degradation gene ABAOX3 was up-regulated.Therefore miR408 improves rice drought tolerance by indirectly regulatingthe expressions of POD,SODA1,RD22,b ZIP46,ABAOX3 and ZEP1.Eventually resulting in rice growth and tolerance to stress is altered.Overall,the results demonstrate that zma-miR408 might involved in drought stress responses,emphasizing the central regulating function in plant survival.Under drought stress,miR408 might alters plants adaptive mechanism through copper homeostasis adjust.Mi R408 might be part of this copper homeostasis regulation pathway to fine-tune the abiotic stress response and plant growth.