Breeding Of Excellent Strains And Study On Mutation Traits In SP5-SP6 Generation Of Aerospace Mutagenesis Andrographis Paniculata

Andrographis paniculata(Burm.f.)Nees is one of the traditional bulk medicinal herbs in China,which is known as the "natural antibiotic" for its effect of clearing heat and detoxifying,cooling blood,and reducing swelling.At present,most of the A.paniculata species in China are mainly artificial cultivars with a single genetic background.The development of genetic diversity of A.paniculata germplasm resources has been seriously hampered by factors such as growth environment restrictions and lagging cultivation technology.The application of aerospace mutagenesis breeding technology to the selection and breeding of new varieties of A.paniculata can,to a certain extent,solve the problems of shortage of germplasm resources and poor quality.In this research,we compared the differences in biological traits and active component contents of aerospace mutagenesis A.paniculata SP5-SP6 generations,combined with their genetic stability and correlation analysis,so as to achieve the breeding of high quality and high yielding A.paniculata strains.At the same time,we used comparative transcriptomics to study the differences between aerospace mutagenesis A.paniculata trichome mutant strains and normal strains and the causes of mutation formation.Functional annotation and enrichment analysis were performed for differentially expressed genes(DEGs)to identify key regulatory pathways and potential functional genes,which were essential references for the evaluation and innovation of A.paniculata germplasm resources.The main findings were as follows:1.The growth and development cycle of aerospace mutagenesis A.paniculata was affected to some extent.Observing the dynamic growth and development patterns of the aerospace mutagenesis A.paniculata SP5-SP6 generation,it was found that the growth cycle of H4-3,H29-2,H31,H118,H119 and H120 strains in the SP5 generation was significantly earlier and the overall growth condition was better than that of the normal strains.In the SP6 generation,only the H29-2,H31 and H119 strains were observed to retain the early maturity characteristics.2.The morphology of the above-ground parts of the aerospace mutagenesis A.paniculata was significantly mutated.Measurements of the biological traits of the aerospace mutagenesis A.paniculata at harvest time revealed that strains H29-2,H31,H119,H120,D45,D106 and D133 in the SP5 generation were significantly superior to the control strains in several traits,including primary branch number,leaf number,and leaf area,which basically determined the morphological establishment of the A.paniculata.The H29-2,H31,H119 and H120 strains maintained their superiority in these traits in the SP6 generation.3.Space mutagenesis produced remarkable changes in the quality of medicinal parts of A.paniculata.The yield and quality indexes of space mutagenesis A.paniculata at harvest time were measured,and it was found that strains H4-3,H29-2,H31,H36,H119 and H120 in the SP5 generation all had significantly higher content of diterpene lactone active ingredients than the control,as well as strains H4-3,H29-2 and H119 had a dramatic advantage in biomass.In addition,strains H29-2,H31 and H119 also performed outstandingly well in the SP6 generation,especially strain H119,which significantly outperformed the rest of the strains including the control strain in terms of yield and quality.4.The diversity of germplasm resources of space mutagenesis A.paniculata was enhanced.The variation coefficients of biological traits and diterpene lactone active ingredient contents of space mutagenesis A.paniculata SP5-SP6 generations were calculated and ranged from 6.11% to 51.89% and 4.64% to 30.01%,respectively,with significant differences compared to control strains,and the degree of variation of quality indicators was significantly greater than that of morphological indicators.Meanwhile,correlation analysis showed that there was a highly significant correlation between the biological traits and active ingredients of A.paniculata.Three high-quality and highyielding strains,H29-2,H31 and H119,were selected for distinctness,uniformity and stability(DUS)testing based on a combination of genetic stability and correlation.5.The DEGs in the space mutagenesis A.paniculata trilobata mutant strains had specific expression patterns.Functional annotation and enrichment analysis of the DEGs revealed that they were significantly enriched in the secondary metabolite biosynthesis and phytohormone signaling pathways.A total of 38 DEGs were annotated to the Auxin signaling transduction pathway,among which the specific expression of AUX/LAX,AUX/IAA,ARF,GH3 and SAUR genes contributed to the formation of mutations for the excellent trait of trichome verticillation in A.paniculata.In addition,the specific up-regulated expression of key enzyme genes such as DXS,DPPS,GPPS,FDPS and IDI in the terpenoid backbone biosynthesis pathway promoted the synthesis and accumulation of diterpene lactone active components in A.paniculata.