Establishment Of A Metabolomics Study Method In Tomato Fruit And Prediction Of MQTLs

Tomato is a vegetable crop cultivated in all over the world,its fruit is famous for abundant nutrient substance and special flavor that can be processed into many kinds of eatables through various ways.A large number of metabolites not only play an important role in Physiological and biochemical activities,defense against biotic and abiotic stress,and fruit quality in the plant,but also supply abundant resource for nutrition,energy and medicine of human being.As the bridge of genome and phenome,metabolomics research has the benefit to understand the connection of genome and phenome.Metabolomics research is based on a set of techniques and methods that can detect and identify metabolites effectively.In this study,we studied the LC-MS data acquired from the fruit of tomato nature population.To set up a system suitable for analyzing tomato fruit metabolomics,we set up MS2T(MSMS Tag)library,metabolites identification,phenotypic data extraction,and genome-wide association study are performed.The results of the study are summarized as follows:1.The establishment of MS2 T library.Firstly,we performed differential analysis between cultivar and wild type tomato to acquire the metabolites which have content difference between them.After that,the metabolites which we are interested in are studied further within them and then collected MSMS data by Target MSMS mode.Furthermore,Auto MSMS mode is also used to acquire MSMS data autonomously.Finally,102 clear MSMS spectra are acquired in the aggregate,comprised of accurate m/z,retention time,fragments peaks,and so on.2.The identification of metabolites.Three ways were used to predict these metabolites: 1)standard compounds;2)searching for databases and literature;3)assigning metabolites according to the pattern of spectra.Finally,A total of 42 metabolites were identified and five of them are the first time to be identified in tomato.3.Relative quantification of metabolites.As we know,the original quantitative method of the instrument is very complicated,which is not conducive to the batch processing of metabolites.Consequently,we try to find a parameter that could replace metabolites content in the sample for relative quantification.Finally,we made it.Firstly,we extracted the phenotypic data of metabolites by this method,and then GWAS was performed to mine the metabolites-related QTLs.And then,we selected the SGAs(alkaloids)that have been reported to verify the usability of our method.The results showed that the QTLs we obtained are close to those of the literature and demonstrated our method is available and useful for operation.4.Umbelliferone,a coumarin family substance,was identified in the experiment and conducted GWAS.This is the first time identifying the substance in tomato.Coumarins mainly play a role in the invasion of pathogens and enhancing the ability of plants to resist abiotic stresses.So far,there is no study at the level of gene in tomato,so it is worth to research further.