Analysis On The Flowering Rhythm Mechanism Of Hemerocallis Citrina

Hemerocallis citrina is one of the characteristic vegetables in China.The flowering period of the same germplasm was only 12 h.There were differences in the flowering of the same germplasm in different longitude and latitude regions,but they all had obvious rhythm characteristics of opening at night and closing at day,This phenomenon is of great significance to the research on the flowering rhythm mechanism and the harvest time of Hemerocallis citrina.This study conducted a preliminary exploration of the changes in the flowering rhythm,light response parts and flowering dynamics of the Hemerocallis citrina ‘Datong Huanghua’ under different photoperiods;Observe and analyze the dynamic changes of the epidermal cells of the tepals during the opening and closing of Hemerocallis citrina,providing a basis for further exploring the response mechanism of Hemerocallis citrina flowering cytology;Metabonomics analysis was carried out at five time points during the flowering process of ‘Datong Huanghua’,according to the enrichment analysis of differential metabolites,further mining of metabolites related to the opening of Hemerocallis citrina petals;Select two groups of floral organs at the same time point under different circadian rhythms for transcriptome sequencing,screening candidate genes related to light response and photoperiod flowering among differential genes;Combining transcriptome sequencing data to construct a Hemerocallis citrina photoperiod flowering regulatory network,laying the foundation for regulating the flowering rhythm of Hemerocallis citrina,it is of great significance to further explore the flowering mechanism of Hemerocallis citrina and reveal the diversity of flowering mechanism.The main research conclusions are as follows:In order to explore the influence of photoperiod on the flowering rhythm,the day and night of the‘Datong Huanghua’ were reversed,and the biological clock of the flowering rhythm was about 12 h before and after the treatment;By observing the flowering time of the ‘Datong Huanghua’ under five different photoperiod conditions of 9D/15L(Nine hours of darkness/fifteen hours of light),12D/12L(Twelve hours of darkness/Twelve hours of light),14D/10L(Fourteen Hours of Darkness/Ten hours of light),16D/8L(Sixteen Hours of Darkness/Eight hours of light)and CD(Continuous darkness),it was found that the petal opening time under 9D/15 L,12D/12 L,14D/10 L and 16D/8L photoperiods was delayed by about 1 h in sequence,the opening time of petals under CD treatment is basically the same as that of 16D/8L,which proves that the photoperiod changes have a significant effect on the flowering rhythm.In order to find the key parts of Hemerocallis citrina that respond to Photoresponsive flowering,In this study,the flower organs and leaves of the ‘Datong Huanghua’ were shaded,It is found that only the shading of the flower organs can change the flowering rhythm of Hemerocallis citrina;The different tissues of the outer petals,inner petals,pistils and stamens are excised,and the flowering time remains unchanged,it is speculated that the inner petals and outer petals of Hemerocallis citrina respond to and regulate the photoperiod flowering circadian clock;It was found by optical microscope that the movement of the petals in the process of flowering and closure was mainly caused by the asymmetrical changes in the length and width of the epidermal cells in the upper and the base of the petals and the expansion and contraction of the cells on both sides of the petals.Metabonomics analysis was carried out on flower organs of ‘Datong Huanghua’ at five different flowering stages,and a total of 6,456 metabolites were obtained.Compare the samples with each other to obtain a large number of different metabolites,through KEGG enrichment analysis of differential metabolites,a total of 19 metabolic pathways were screened.The analysis found that metabolites are mainly enriched in pathways related to nutrition and energy metabolism during flowering,and differential metabolites are mainly enriched pathways before flowering Is the starch and sucrose metabolic pathway and the galactose metabolic pathway.It shows that the flowering process of Hemerocallis citrina is closely related to carbohydrate metabolism.Transcriptome sequencing was performed on two groups of flower organs at the same time point under different circadian rhythms,and a total of 90 GB of data was obtained.After filtering,524,445,022 of reads was obtained,and 99,513 genes were obtained to construct the Hemerocallis citrina flower organ transcriptome database.A total of 13,236 differential genes were obtained from the difference analysis of the 4 groups of samples.Perform GO and KEGG enrichment analysis for each comparison group,and classify the 4 groups of differential genes into 51,51,50,46 categories and 134,130,108,and 100 metabolic pathways respectively.Among them,the plant circadian rhythm pathways are significant respectively Enriched 32,26,6,14 differentially expressed genes.According to the reported genes that regulate development in response to light and gene functional annotation results in the Hemerocallis citrina transcriptome,and a total of 34 genes related to the regulation of light responsive development were obtained.These genes are mainly concentrated in plant circadian rhythm,photoperiod and photomorphogenesis process;With reference to the published photoperiod flowering genes and their regulatory relationships in Arabidopsis thaliana,a total of 13 related genes were annotated in the Hemerocallis citrina transcriptome,and the Hemerocallis citrina photoperiod flowering regulatory network was initially constructed.This process is mainly regulated by key genes such as PHYA,GI,CO,FT and SPA1.