Phenotypic,physiological And Transcriptome Analysis Of Triploid Tea Plant Varieties

After the formation of polyploid plants,they often undergo a series of changes in their morphological characteristics and physiological activities that benefit growth and enhance the ability of adapting to environment.The tea plant(Camellia sinensis)is a globally important leafy cash crop with a wealth of germplasm resources.Currently,cultivars are mostly diploid,with a few artificially induced and natural mutant triploid tea plant cultivars,but there are fewer reports on identification and systematic evaluation of triploid tea plant resources.Therefore,to investigate whether triploid tea plants have the beneficial variations common to polyploid plants,we evaluated the polyploid effects of tea plants from various aspects.Firstly,we selected six tea plant cultivars(strains)for each triploid and diploid to analyze the phenotypic differences between two groups,and then analyzed the photosynthetic advantages of triploid tea plants by using transcriptome sequencing and measuring relevant physiological indicators.At the same time,we also screened stable reference genes for quantifying the expression of important genes in different tea plant cultivars,in order to analyze the expression changes of key genes in different ploidy tea plants.The main research elements and results are as follows:1.We firstly used flow cytometry to verify the ploidy level of 12 tea plant cultivars(strains).And then by comparing the leaf characteristics of the different ploidy groups,it was found that triploid tea plants had longer and wider leaves,increased leaf area,increased stomatal volume and reduced stomatal density compared to diploids.2.RNA-seq was performed on 12 tea plant cultivars(strains)and hybrids from two ploidy groups.We screened 5244 DEGs by preliminary comparison of transcriptome data from the two hybrid samples.GO and KEGG enrichment analysis results revealed that DEGs were mostly concentrated in metabolic pathways related to photosynthesis.And then,11 important genes were selected from these metabolic pathways.Validation results by q RT-PCR revealed significant differences in the expression of Cs MYB114 and Cs NDH2 between the two ploidy groups.In addition,transcriptomic data showed that the expression of these two genes showed the same patterns in different ploidy tea plant cultivars.Continued research revealed that chlorophyll content,net photosynthetic rate,stomatal conductance and transpiration rate were significantly higher in triploid tea plants than diploids.3.We selected 23 candidate reference genes and evaluated the expression stability of each gene in different tea plant cultivars by using ge Norm,Norm Finder,Best Keeper,ΔCt method and Ref Finder.The results showed that Cs UBC3 and Cs UBC2 had the highest expression stability.By q RT-PCR determination of the expression patterns including Cs SIP and Cs STS,the stability of the recommended reference genes was successfully verified in the tender shoots and mature leaves of various tea plant cultivars as well as in other cultivars.