The Functional Study Of Arabidopsis BRCA1 In The Dehydration Stress Response

Drought stress is a crucial form of abiotic stress,affecting plant development of all stages seriously.Under drought stress,plant cells shrivel,toxic substances are accumulated,protein structure and stability are damaged,which affects plant photosynthesis and respiration.Under long-term drought conditions,the growth rate of plant leaves slows down and accelerates the yellowing and shedding of old leaves.Under drought stress,Reactive oxygen species(ROS)is not only a byproduct of aerobic metabolism,but also an important second messenger in plant.It participates in many physiological processes including abiotic resistance,hormone regulation and cell growth.A large number of studies have shown that BRCA1,as an important tumor suppressor protein,is involved in many physiological processes including cancer suppression,DNA damage repair,regulation of cell cycle and it can also combine with a large number of transcription factors and regulate their activities in mammals.However,the study of this protein in plants is limited to the repair process of DNA double strand breakage and there is no relevant report on abiotic stress.Therefore,in this study,we obtained BRCA1 homologous gene mutants in Arabidopsis thaliana as experimental materials,to explore its role in drought stress response.The main conclusions of this study are as follows:(1)Arabidopsis BRCA1 localizes to nucleus and BRCA1 expresses in root,flower,leaf,cotyledon and silique;(2)brcal mutants were more drought-resistant than WT through short-term water lose experiments and long-term drought experiments;(3)Compared with WT,brcal mutants were ABA-sensitive through observing leaf stomata under ABA treatment;(4)By taking advantages of genome-wide RNA-sequencing analysis,we found that BRCA1 affects the expression of a series of ROS-related genes;(5)The results of NBT staining and DAB staining showed that the contents of H2O2 and O2-in brcal mutants were higher than those in wild type.Based on the above experimental results,we found that BRCA1 in Arabidopsis had a negative regulatory role in drought stress and ABA response pathway.We hope that the results of this experiment can provide some theoretical basis for the further study of the molecular mechanism of drought stress response.