Function Of AtSCL26 And AtSCL29 In The Root Development Of Arabidpsis Under Nitrogen Stress

GRAS fanily are plant-specific transcription factors that have been reported to participate in plant development and stress responses.AtSCL29 and AtSCL26 are the members of GRAS family in Arabidopsis thaliana.It speculated that AtSCL29 and AtSCL26 are potentially related to strigolactone(SL)biosynthesis and signalling pathway of nitrogen response based on previous researches.So we focused on the function of AtSCL29 and AtSCL26 in the root development of Arabidopsis thaliana under nitrogen stress condition in this study.The main results are as follows:1.Bioinformatics analysis showed that the highest expression of AtSCL29 was in roots,followed by flowers,leaves and seeds while AtSCL26 mainly expressed in flowers,followed by roots.Subcellular localization informations revealed that AtSCL29 was distributed highly in nuclei,cytosol and mitochondria while AtSCL26,in addition to nuclei,mitochondria and cytosol,it was also located in plasma membranes and cell walls.The expression of GFP gene driven by AtSCL26 promoter showed that AtSCL26 expressed in the root of seedlings.In details,it was in root caps of primary roots and mature lateral roots,elongation zones and stele of primary roots and lateral root primordiums.2.Under normal conditions,there were no distinct differences on primary root length between the mutants of AtSCL29 and AtSCL26 including single and double murtants when compared with wild type Col-0,so did overexpression lines of AtSCL26.But overexpression lines of AtSCL29(AtSCL290X-3 and AtSCL290X-6)showed that average primary root length were significantly shorter than Col-0 8 days after growing on the medium.Besides,the boling of AtSCL290X-3 and AtSCL29OX-6 were obviously later than Col-0.The phenotype of rosette leaf showed obvious difference between overexpression lines of AtSCL29(AtSCL290X-3 and AtSCL290X-6)and Col-O.3.Under the condition of 9.895 mM nitrogen concentration on the medium(commercial product of low nitrogen concentration),the average primary root length of AtSCL26-870 mutant and AtSCL29-29b mutant showed no significant difference when compared with Col-0.Next,we chose the condition of 0 mM NO3' on the medium,the results showed that the average primary root length of materials inchading mutants of AtSCL26(360 and 600),mutant of AtSCL29(29b),double mutant of AtSCL26 and AtSCL29(600x29b),and overexpression lines of AtSCL26 had no significant difference when compared with Col-0;However,the average primary root length of overexpressien lines of AtSCL29(AtSCL290X-3 and AtSCL290X-6)were shorter than Col-0,in particular,there was significant difference between AtSCL290X-3 and Col-0.Under the condition of 0 mM NO3-in hydroponic system,AtSCL26-600 mutant howed no significant difference when compared with Col-0.4.Under the condition of 0 mM NO3' on the medium,the overexpression line of AtSCL26(fin-1),whose background is Ws ecotype,showed no sigpificant difference on average primary root length when compared with Ws;the overeqpression lie of AtSCL29(835-1,Ws ecotype),showed significantly lbnger primary root length than Ws 7 days after growing on the medium.In conclusion,single mutants and double mutant of AtSCL29 and AtSCL26 and overexpression lines of AtSCL26,whose background is Col-0 ecotype,showed no significant phenotype on root when compared with Col-0.However,overexpression of AtSCL29 had a significant effect on the development of roots,leaves and bolting under normal condition.Under nitrogen stress,overexpression of AtSCL29 also affected root development in Arabidopsis thaliana.Besides,knock down of AtSCL29 in the background of Ws ecotype promoted the elongation of primary root under nitrogen stress.