Study On Tissue Culture Of Populus Simonii ×(Populus Pyramidalis +Salix Matsudana) Cv.’poplaris’ And Screening Of Seedling Salt Stress Genes

Salt stress is one of the main abiotic stress factors affecting plant growth and crop yield.The CBL-CIPK signaling network plays an important role in plant stress response.In recent years,the ecological environment in Northwest China has been deteriorating.Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’ has the characteristics of drought resistance,rot resistance,and excellent materials,and is suitable for cultivation in North China and Northwest China.However,Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’ has limited salt and alkali tolerance,which is a major bottleneck for ecological afforestation in saline and alkali regions in the northwest.Screening salt-resistant candidate genes and breeding salt-resistant plants are of great significance to improve the ecological environment of saline-alkali land in Northwest China.The tissue culture system of Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris ’ is seldom studied.In this paper,a tissue culture system was established by direct induction of axillary buds and three different explants induce adventitious buds,in order to lay the foundation for the selection of salt-tolerant varieties of Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’.At the same time,in order to screen candidate genes for salt tolerance,the biological information of CIPK gene family of Populus trichocarpa and salt stress response of Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’ CIPK gene family were analyzed.The main findings are as follows:1.Analysis of the physicochemical properties,phylogeny,gene structure and cis-elements of the CIPK gene family,31 CIPK genes of Populus trichocarpa were identified,and named as PtCIPK1-PtCIPK31 according to their chromosomal positions.Analysis of physicochemical properties showed that the amino acid sequence of the CIPK gene family of poplar was between 396 and 549 amino acids,and the molecular weight of the protein was about 44.62-61.40kD,with a high isoelectric point(PI>7.0).Analysis of gene results showed that the CIPK gene family of poplars can be divided into two categories:introns and non-introns.Analysis of the cis-element of the promoter indicated that the CIPK gene family of poplar contains a variety of abiotic stress elements,and also laid the foundation for subsequent gene function research.2.Based on bioinformatics analysis,this research takes Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’ as the research object to explore the response of the CIPK gene family to salt stress,with a view to laying the foundation for subsequent varieties improvement.The analysis of qRT-PCR results showed that when the roots were subjected to salt stress of 200 mM NaCl for 12 h,the CIPK gene expression of most of Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’ was high.Based on this work,CIPK21/22/27 would be used as candidate genes for salt tolerance.The salt stress expression analysis of the CIPK gene family in Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’ has laid the foundation for further research of the poplar CIPK gene family.3.In this research,the tissue culture system of Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’ wss induced by the direct induction of axillary buds and three different explants induce adventitious buds.The experimental results are as follows:(1)The best disinfection method for direct induction of axillary buds by Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’ is 75%ethanol for 30 s,0.1%mercuric chloride for 15 minutes.The best medium for stem axillary bud induction was 1/2MS;the best medium for Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’ to induce axillary buds was 1/2MS+0.5 mg/L 6-BA+0.03 mg/L NAA.The optimal medium for inducing axillary buds of Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’ is:1/2MS+0.5 mg/L 6-BA+0.03 mg/L NAA.Populus simonii x(Populus pyramidalis+Salix matsudana)cv.’Poplaris ’(stem segment induced axillary buds)proliferation medium is:1/2MS+0.5 mg/L 6-BA+0.2 mg/L NAA +0.5 mg/L GA3.The best disinfection method of Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’ leaves,stem segments and petioles is 2%NaClO for 8 min.The best medium for inducing adventitious buds in leaves is MS+0.3mg/L TDZ+ 0.3 mg/L IBA;The best medium for stem callus induction was MS+1.0 mg/L 6-BA+ 0.1 mg/L NAA,and the best medium for differentiation was MS+ 1.0 mg/L 6-BA+0.5 mg/L IB A;The best medium for Populus simonii ×(Populus pyramidalis+Salix matsudana)cv.’Poplaris’petiole induction callus is:MS+0.5 mg/L 6-BA+0.1 mg/L NAA,and the optimal medium for differentiation is:MS+1.0 mg/L 6-BA+0.5 mg/L IBA.The best medium for adventitious bud rooting was 1/2 MS+ 0.3 mg/L IB A+0.08 mg/L NAA.