Isolation And Characterisation Of SLAGO Genes And Study On Biological Function Of Mir168and AGO1in Tomato

Post-transcriptional modification is an important regulating process in plants,which functions in almost all developmental progress as well as defence response toplant virus. miRNA is a small molecular that could participate in post-transcriptionalregulation in leaf morphogenesis, phase transition, formation of gamete, miRNA is oneregular regulation pathway and play an important role in plants, AGO protein is a coreelement of RNA induced RNA silencing complex, which bound to miRNA and represstarget genes.The AGO gene family were identified and characterized in the tomato genome.Gene expression detection, homologous analysis and subcellular localization wereperformed between15putative conserved AGO.There were15conserved AGO genes in the tomato genome, and they weregrouped into three subfamilies: AGO1, AGO2and AGO4subfamily accordding to theirsimilality to AtAGO1, AtAGO2and AtAGO4respectively; Most of SlAGO genes wereconstitutivly expressed in root, stem, leaf, flower and each developmental stages offlower bud, stamen and ovary, but AGO5could only be detected in reproductivesystem, while AGO4D expressed significantly higher in early stage of fruitdevelopment; SlAGO is localized to cytoplasm and nucleus, but cellular membrane andnuclear membrane localization were observed for SlAGO1A, SlAGO1B, SlAGO5andSlAGO10.miR168and AGO1are post-transcriptional regulators. miR168is able to regulateAGO1in the post-transcriptional level. Meanwhile, AGO1can bind to miR168tofunction as regulator. This particular feedback to feedback cyclic regulation hasattracted much attention of scientific researchers. The research on the pathway howmiR168regulates AGO1and the reason why plants develop this feedback cyclicregulation in core regulator of post-transcriptional pathways seems rather important.Therefore, to study the biological meaning of miR168and AGO1feedback regulationwill improve our understanding of the biological functions of miRNAs in growing anddevelopmental process of tomato.In this study, sequence of miR168and its target gene SlAGO1A/SlAGO1B wereobtained on the basis of bio-informatics analysis. Furthermore, miR168-functiongained transgenic plants, miR168-resistance transgenic plants and miR168-sponge transgenic plants were employed to analysis the function of miR168andSlAGO1A/SlAGO1B in tomato. Conclusions were as follows.[1] In tomato, there are15genes belonged to AGO gene family and onlySlAGO1A and SlAGO1B were cleaved by miR168.[2] SlAGO1A and/or SlAGO1B were accumulated in miR168-resistance andmiR168-sponge transgenic plants, at the same time, miR168was accumulated in thethree types of transgenic plants, indicating SlAGO1A/SlAGO1B could bind to miR168to achieve self-regulation of miR168;[3] miR156and miR172, important regulators of phase transition, were impactedby influencing expression of SlAGO1A and SlAGO1B. Simultaneously, losing oscillateexpression of miR168during diurnal cycle resulted in delay of floral transition inmiR168-resistance transgenic plants;[4] Accumulation of miRNAs were influenced by miR168andSlAGO1A/SlAGO1B, which led to leaf epinasty, defects in shoot meristem and fruitabinormity in miR168-resistance transgenic plants.Furthermore, the degradome sequencing of tomato was analysis in this study. Thiswork completed the network in regulating miRNAs by post-transcriptional controllingof SlAGO1A/SlAGO1B via miR168, and then target genes of the influenced miRNAwere impacted, which consequently altered developmental progress in tomato.