Breeding Of Excellent Strains And Study On Stress Resistance In SP9 Generation Of Aerospace Mutagenesis Cassia Obtusifolia

Cassia obtusifolia L.belongs to the Cassia genus in the Legumfamily,and its mature seeds are called Cassiae Semen.As a common traditional Chinese medicine,Cassiae Semen have the effect of improving vision and relieving constipation.Currently,Cassiae Semen sold in the market face problems such as insufficient yield,inconsistent quality,and uneven quality.However,current research on Cassiae Semen mainly focuses on the extraction and separation of chemical components,the development of health products,and pharmacological effects,with little attention given to breeding new varieties.In this study,space-flight mutation SP9 generation of C.obtusifolia(1,2,3,4,5)and the normal C.obtusifolia(CK)were used as the research objects.The agronomic traits,seed biological characteristics,anthraquinones content,salt resistance and SOD(Superoxide Dismutase)gene family of space-flight mutation SP9 generation and normal control material were recorded and analyzed.The research mainly includes the following parts:1.The overall agronomic traits of space-flight mutant strains were superior to those of normal control,among which strain 3 had the best comprehensive agronomic traits,with significantly higher plant height,stem thickness,crown width,number of branches,and yield per plant than the normal control(p<0.05).The space-flight mutation C.obtusifolia strains showed better seed biological characteristics than the normal control,especially in terms of germination rate,thousand grain weight,and antioxidant enzyme activity.Using HPLC to detect six anthraquinone compounds in space-induced mutagenesis SP9 strains and normal control Cassiae Semen,the results showed that the contents of aurantio-obtusin,emodin,and physcion in mutant strains 2,3,and 4 were significantly higher than those in the normal control(p<0.05).Additionally,the content of rhein and chrysophanic acid in mutant strain 4 were significantly higher than those in the normal control(p<0.05).A comprehensive analysis of the three indicators of agronomic characteristics,seed biological characteristics,and effective components using the membership function method showed that the average membership function values of the mutant strains were higher than those of control.The average membership function values of C.obtusifolia strains ranked from high to low were 3,2,4,1,5,CK,with strain 3 having the highest average membership function value and being the best strain.This study provides data support for screening high-yielding and high-quality mutant C.obtusifolia varieties.2.By comparing and analyzing the phenotype,antioxidant enzyme activity,chlorophyll content,photosynthetic parameters,effective component content,and anthraquinone synthase gene expression in SP9 C.obtusifolia and normal control under salt stress,the salt tolerance of different C.obtusifolia strains was comprehensively evaluated.The research results showed that the antioxidant enzyme activity of different C.obtusifolia strains increased and then decreased with the change of salt stress concentration,with variation between tissues.The space-mutagenized strain showed higher antioxidant enzyme activity than the control strain.The chlorophyll content and photosynthetic rate decreased in all strains under salt stress,while the anthraquinone content in the seeds increased under salt stress,with with the space-mutagenized strain showing a greater increase than the control strain(p<0.05),particularly for aurantio-obtusin and rhein,which increased by 2.2 and 2.8 times in strain 3,respectively.Using correlation analysis,principal component analysis,and membership function analysis,the study concludes that the salt tolerance of different C.obtusifolia strains from strongest to weakest is 3,4,2,1,5,CK.This study provides a theoretical basis for selecting new high-quality varieties of C.obtusifolia with strong salt tolerance.3.Through the whole-genome analysis of the SOD gene family in Cassia obtusifolia,eight SOD genes were identified,unequally distributed on 6 chromosomes.Phylogenetic analysis showed that the C.obtusifolia SOD genes clustered into two groups and were more closely related to soybean.Several cis-acting elements,including light-responsive elements,hormone-responsive elements,and abiotic stress-responsive elements,were predicted in the promoter region of St SOD genes.Using q RT-PCR,the response patterns of the 8 C.obtusifolia SOD genes to various abiotic stress such as drought,Na Cl,heavy metal(cadmium),cold,and heat were analyzed.The results showed that the expression patterns of St SOD genes were tissue-specific and that different SOD genes had specific response patterns to abiotic stress.The screened St SOD genes in this study will provide references for molecular-level resistance research of space mutagenesis in Cassia obtusifolia.