Expression Patterns Of Nucleotide Transferases (NTP) In Arabidopsis And Regulation Of NTP2 On Root Development

Nucleotide transferase protein(NTP)in plants can catalyze the non-template tailing of RNAs,thereby changing the stability of RNAs.There are 10 members in the Arabidopsis nucleotide transferase family.Among them,HESO1 /NTP1 and URT1/ NTP3 are extensively studied,and their functions are relatively clear,but the functions of the other 8 members remain unknown.This study first investigated the tissue specificity and subcellular localization of 10 NTPs in Arabidopsis.Fusion expression vectors of these 10 NTP gene promoters and GUS gene were constructed and transformed into Arabidopsis thaliana.Histochemical staining was used to observe the tissue-specific expressions of these 10 NTP genes: The study found that except for NTP10,which is not expressed at the seedling stage,other NTPs show a certain degree of expression at different developmental stages and in different tissues;and overexpression vectors of these 10 NTP/GFP fusion gene driven by 35 S promoter transformed into tobacco and Arabidopsis,and the subcellular localization of 10 NTPs in Tobacco epidermal cells and Arabidopsis root tip cells were observed using scanning laser confocal.It was found that in tobacco epidermal cells,NTP1 /HESO1,NTP2,NTP3 /URT1,and NTP7 were localized in both the cytoplasm and nucleus.NTP6 is localized in the cytoplasm,and NTP10 is specifically localized in the nucleus.In root cells of Arabidopsis thaliana,NTP2 and NTP6 are localized in the cytoplasm and nucleus,while NTP1 /HESO1,NTP3 /URT1,and NTP7 are localized in the cytoplasm.So far,researches on Arabidopsis NTPs have been focused on HESO1 and URT1,and this study investigated the expression patterns of the 10 NTPs in Arabidopsis,which lay a foundation for further research on the functions of nucleotide transferase in Arabidopsis,and provide directions for our further research.Based on the results of tissue expression specificity and subcellular localization of 10 NTPs in Arabidopsis,NTP2 has significantly higher expression level in roots,and previous studies in our lab showed that ntp2 mutants had the phenotype of shortened root lengths,thus,further explored the molecular mechanisms of NTP2 in the regulation of Arabidopsis main root development.We first observed the phenotypic differences,including the growth status of the main root,germination rate,root hair formation,and root tip cell shape and number,between the mutant and wild-type and over-expressing lines,and then we measured the content of plant hormones in the roots,investigated the effects of exogenous hormones on root development,and analyzed transcriptome sequencing and small RNA sequencing,from these results,we have concluded that NTP2 regulates enzyme activity of methyl transferase in the methionine cycle through the stabilization of six mi RNAs: mi RNA163,mi R395,mi R398,mi R161,mi R319,and mi R846,which in turn,affects sulfur absorption,reactive oxygen scavenging,and ATP synthesis,therefore affect the synthesis of ethylene,and further regulate the synthesis of plant hormones such as auxin to further affect the growth and development of plant roots.This study first revealed the relationship between Arabidopsis nucleotide transferase and plant root development,and for the first time revealed the relationship between Arabidopsis nucleotide transferase and plant hormone synthesis such as ethylene synthesis and auxin synthesis.