Function Analysis Of AtCAP1 In Vesicle Trafficking Of Root Hair Cell

Due to the unmovable and the variable environment conditions mechanisms of regulating plant growth and development are complex.Since cell is the basic unit,revealing the mechanisms of its growth regulation is the focus of biological research.During cell growth,membrane trafficking plays important roles.Root hair cell is a typical cell for tip growth.In the process of root hair growth and development,large amount of substances are rapidly synthesized and aggregated at the tip,membrane vesicles trafficking plays important role in cell growth.Arabidopsis protein kinase CAP1([Ca2+]cyt-associated protein kinase)belongs to the CrRLK1L family and participates in the regulation of Arabidopsis root hair cell growth and development.CAP1 is involved in the regulation of the NH4+-mediated signaling pathway in regulating root hair growth.The root hair of CAP1 T-DNA insertion mutant showed abnormal gradients of Ca2+,pH and ROS at the tip,which were in accordance with the abnormal root hair in the mutants.At the same time,vacuolar development,microfilament arrangement and membrane vesicles distribution and fusion were abnormal in cap1 mutant root hair cells.However,when NH4+in MS medium was depleted,the hair length and density of the cap1 mutant were restored to that of the wild type,and at the same time intracellular gradients of Ca2+,pH and ROS were re-establishment.Considering the formation of vacuole is the result of the cellular membrane traffic,and microfilament and vesicle are all important factors in influencing vesicle transport,the abnormaities of these in the capl mutant indicated that CAP1 may influence the transport of membrane vesicles of root hair cells.Therefore,in order to further explore the mechanism of cell growth and development regulated by CAP1,we studied the membrane vesicles transport of root hair cells.We used vesicle transport marker lines of wild type and cap1(got by crossing)to examine the effects of NH4+and CAP1 on membrane trafficking.The observation of the root hairs of wild-type and cap1 mutants showed that ammonium can regulate the growth and development of root hair and the synthesis of vacuole,and CAP1 also participates in this process.Obesvation of the membrane vesicle transport marker lines,showed that the different fluorescence distributions of Golgi apparatus,trans Golgi network,vacuoles,and endosomes in WT and capl on MS media,suggesting that CAP1 participates in and influences the distribution and development of these hair cells in root hair cells.Ammonium treatment also showed variation of the fluorescence exited in the wild type,indicating ammonium influences the development and distribution of trans-Golgi network,vacuoles,recycled endosomes,and primary endosomes in root hair cells.The T-DNA mutant materials analysis showed their hair length had significant difference,indicating that vesicular transport is important for hair growth with WT.Double mutation with cap1 were compared to cap1 mutants.The root hair of their suggesting that CAP1 and these genes regulate the growth and development of the root hair together.Our experimental results show that:NH4+can regulate the morphological development of root hairs and vacuoles formation,both CAP1 and NH4+participate in and regulate the inner membrane cell trafficking of Arabidopsis root hair cells.