| Drought is one of the main abiotic stresses that restrict plant growth.Chrysopogon aciculatus is an important perennial herb of Chrysopogon in Gramineae.It is of great significance to study the drought resistance mechanism of pennisetum purpureum,because it has rich germplasm resources and developed underground stems and stolons.In this study,40 accessions of C.aciculatus were used as materials,the drought-resistant and droughtsensitive accessions were selected from 40 accessions by conprehensive evaluation of their drought resistance using morphological indexes.Through the analysis of physiology and transcription level of extreme germplasm,the mechanism of drought resistance of C.aciculatus was preliminarily explored.The main contents and results are as follows:1.Optimization of drought-resistant system of germplasm resources of C.aciculatusThree accessions were selected and six PEG-6000 concentration gradients of 0,10%,15%,20%,25% and 30% were set to screen the drought resistance concentration.The results showed that with the increase of PEG concentration,the same index was significantly different among treatments(P<0.05).When PEG concentration was 15%,there were significant differences among germplasm CA59,CA39 and CA23(P<0.05).When the concentration of PEG was 20%,the inhibition degree of CA59 was much greater than that of CA23,and the plants were severely stressed under 30% PEG treatment,which led to the death of plants.Therefore,15% and 20% PEG concentrations were selected to evaluate the drought resistance of a large number of S.japonicum germplasm resources.2.Preliminary evaluation of drought-resistance among 40 C.aciculatus germplasm resources40 C.aciculatus germplasms were used as materials to simulate drought stress in PEG-6000 solutions at three concentrations of 0,15% and 20%,and preliminary evaluation of drought resistance of 40 C.aciculatus germplasm resources.Results showed: with the increase of PEG concentration,the withering rate and wilting coefficient of different C.aciculatus germplasm under drought stress show an increasing trend and there have significant difference between different treatments(P<0.05).T1 treatment promote root growth,while T2 treatment inhibited,and there were significant differences among germplasm(P<0.05).The drought resistance of C.aciculatus was comprehensively analyzed by membership function,which was divided into drought-resistant germplasm(CA04 and CA26),and drought-sensitive germplasm(CA78 and CA40).3.Analysis of physiological differences of C.aciculatus under drought stressAntioxidant enzyme activity and malondialdehyde content of drought-resistant germplasms CA04 and CA26 and drought-sensitive germplasms CA78 and CA40 were determined to study the physiological differences of drought stress on different droughtresistant germplasms.Result showed: there are significant differences in different treatment time of the same germplasm and after 6 hours of treatment,the change trend of each index showed a significant turning point,which indicated that the stress response appeared,and after 48 hours of treatment,the activities of the three enzymes all showed a sharp downward trend,and the enzyme activities of drought-resistant germplasm were higher than those of drought-sensitive germplasm.The MDA content increased gradually with the extension of stress time and there are significant differences in different treatment time of the same germplasm.After 72 h treatment,the MDA content of CA40 and CA26 was lower than that of CA04 and CA26,which indicated that the cell membrane system of drought-resistant germplasm leaves could maintain a high degree of integrity and suffered less damage from the environment.4.Transcriptome analysis of leaf response to drought stressBased on the transcriptome analysis of leaves of C.aciculatus(CA26 and CA40),species distribution showed that C.aciculatus was closer to sorghum.A total of 95,139 Degs were detected,including 47,256 up-regulated genes and 47,883 down-regulated genes.GO enrichment analysis showed that DEGs of the leaves mainly involved photosynthesis and chromosome-protein linkage.KEGG enrichment showed that the enrichment degree of differential genes involved in metabolic pathway was the highest,followed by the synthesis of secondary metabolites.The above research provides basic data for the followup study of drought resistance gene validation of C.aciculatus. |
PDF Full Text Request