Mechanism Of Photorespiration Induced H₂O₂ Regulation In Arabidopsis Lateral Roots Development

Roots are important vegetative organs of plants.The morphology of roots not only affects the ability of plants to absorb various nutrients from the soil,but also participates in the regulation of photosynthesis and growth and development of shoots.It has been reported that reactive oxygen species such as H2O2 play an important role in the lateral root development of plants.However,the molecular mechanism by which H2O2 regulates lateral root development remains unclear.The first part of this article uses physiology,genetics,molecular biology and other means to analyze the relationship between H2O2 and lateral root development.Phenotypic analysis showed that the number of lateral roots of cat2 was significantly lower than that of wild-type Col-0.Exogenous treatment with H2O2 and 3-AT,a CAT activity inhibitor,also significantly inhibited the number of lateral roots,and by measuring CAT activity in leaves and roots and The results of reactive oxygen species staining also showed that a large amount of H2O2 accumulated in the primary roots and lateral roots of cat2.By observing the formation of lateral root primordium,it was found that cat2 did not affect the initiation but inhibited the emergence of lateral root primordia.Using cat2 DR5::Luc to detect the change of growth point in roots,The number of growing points in the root of cat2 decreased by about 32%.Studies have shown that auxin plays an important role in the development of lateral roots.The distribution and concentration gradient of auxin in roots promote the initiation of lateral roots.cat2 DR5::Venus was used to detect the expression and distribution of auxin signal in roots.The signal of auxin in leaves,apical and lateral root primordiums of cat2 was significantly decreased,and the growth of Col-0 and cat2 roots was further detected The results showed that the expression of auxin signal gene in cat2 root changed.In summary,the CAT2 mutation inhibited the emergence of lateral root primordia,which in turn led to the reduction of the number of lateral roots in Arabidopsis due to the accumulation of H2O2 to change the expression of auxin signal and auxin-related genes in roots.It is unclear whether CAT2 has been expressed in the roots or not and whether lateral root development is affected after H2O2 removal.Therefore,in the second part of this article,the homozygous transgenic materials p CAT2::CAT2::Venus and p CAT2:: 3x Venus were successfully constructed and screened by Gateway cloning technology.With confocal laser scanning microscopy,CAT2 was found to be mainly expressed in the apical meristem,meristematic cells in the meristematic area,and in the paraffin sheath cells in the elongation area.While the transgenic material after over-expressing CAT2 showed an increased number of phenotypes.These results further confirmed the involvement of H2O2 in the regulation of lateral root development in Arabidopsis thaliana.