| In this study,156 mango germplasm resources were taken as materials for measuring and evaluating external and internal quality of mango fruit to explore fruit quality characteristics and differences among monoembryony,polyembryony and mixture of mono-and polyembryony germplasm,and select good comprehensive quality germplasm resources.In addition,the molecular mechanism of regulating the formation of mango nucellar embryos was explored through transcriptomics and metabolomics.The main results are as follows:1.There were no significant differences in fruit shape,pod beak,pericarp and flesh color,flesh fiber number and texture,fruit shape index,kernel side diameter and kernel mass among monoembryony,polyembryony and mixture of mono-and polyembryony mango germplasm.However,there were significant differences in fruit pit types,fruit aroma and flavor,fruit weight,fruit transect,vertical and side diameter,pericarp thickness and mass,kernel vertical diameter and edible rate among them.2.Three soluble sugar(fructose,sucrose and glucose)and five organic acids(quinic acid,malic acid,shikimic acid,citric acid and ascorbic acid)were detected in fruit.146 germplasm had more sucrose than fructose and more fructose than glucose,the remaining9 germplasm had more fructose than sucrose and more sucrose than glucose,and only one germplasm had no sucrose detected,which can be regarded as the special material;only one germplasm had the highest malic acid content,and the other 155 germplasm had the highest citric acid content.The content of soluble sugar,organic acid,total sugar,total acid,the value of sweetness and ratio of sugar to acid were significantly different among three types of mango germplasm,which provided material guarantee for breeding mango germplasm with suitable ratio of sugar to acid.3.Four carotenoid fractions were detected in this experiment,namely,lutein,zeaxanthin,α-carotene and β-carotene,and only the content of zeaxanthin in monoembryony germplasm was significantly higher than that in polyembryony germplasm.What’s more,the content of zeaxanthin in light yellow flesh was significantly higher than that in creamy yellow flesh,and the content of β-carotene in dark flesh was significantly higher than that in light flesh.It was speculated that yellow flesh was related to zeaxanthin content,and dark flesh color was related to β-carotene content.4.Except for N,Cu and Zn,there were significant differences in the content of P,K,Ca,Mg,Fe,Mn and B among three types of mango germplasm,which might be related to genotypic differences and could be useful for screening germplasm enriched with certain elements for the development of functional germplasm resources.5.It was found that the content of crude fat in monoembryony germplasm was significantly higher than that in mixture of mono-and polyembryony germplasm,which might be related to the difference of photosynthesis.The content of crude fiber in monoembryony and polyembryony germplasm was significantly higher than that in mixture of mono-and polyembryony germplasm,and this difference not only affected the intake of crude fiber,but also related to the taste of fruit.6.According to the comprehensive score F-value,the top 5% of germplasm included‘Mitao’,‘Smith’,‘Miyi No.1’,‘Longzhou No.11’ and ‘Rezuo No.8’.The germplasm‘Mitao’ had the best comprehensive quality,while ‘Hekou local selection 1’ had the worst comprehensive quality,which provided reference for breeding workers to select parents in production.7.Compared with monoembryony,526 and 642 metabolites were up-and downregulated in polyembryony,and 4981 and 5310 genes were up-and down-regulated in polyembryony.With phytohormone synthesis and signal transduction pathways as key metabolic pathways,4 TAA1 genes,2 AUX1 genes,4 TIR1 genes,1 GH3 genes and 2 SAUR genes were up-regulated in polyembryony.It was speculated that the increase of auxin level was conducive to the formation and development of nucellar embryos. |
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