Identification Of The Genes Related To Soft Nose Of Physiological Disease From Jinhuang Mango Fruit By RNA-Seq

Soft nose is a serious physiological disease of mango(Mangifera indica L.) fruit which major damage to the turpentine mango as the representative of Jinhuang mango. Its main disease symptoms are that fruit top turns to soft and yellow firstly and the internal flesh breakdown in fruit ripening, thus affecting mango’s edibility and marketability. This disease widespread occurred in most of major mango growing areas on the world, and has seriously hampered the production of mango. The pathogenesis of soft nose disease is unclear now, ewer molecular biology, most of the studies just stay at the level of physiological metabolism, some studies found that the incidence of disease could reduce through adjusting the formula fertilization treatment, but not completely eradicated it. In this study, used Jinhuang mango as the test material, it was extracted the RNA from two samples of the normal pulp and disease-infected pulp, and analysis by RNA-sequencing, which selected disease-relevant genes from significant differentially expressed between two samples. It is hoped to understand the changes of the metabolic regulation in the infection soft nose disease, and reference to further elucidate the pathogenesis of the soft nose disease. The main results are as follows:1. In this study, compared and analyzed the efficiency of RNA extraction from mango pulp by three methods including isothiocyanate method, SDS method and modified hot borate method. The results showed that total RNA extraction by the modified hot borate method at three methods had best purity and high yield, suited for the next sequencing steps.2. It was acquired more than52.4M reads data by RNA-sequencing. After assembly analysis, were obtained73,712gene sequences from two samples, of which47,508gene sequences had functional annotation and classification. At the same times,18,710gene sequences occurred significantly differentially expressed between two samples, of which5,360were upregulated,13,350were downregulated.3.After analysising of COG, GO and KEGG databases annotated,acquired three ACC synthase homologue genes and two ACC oxidase homologous genes from5,360up-regulated gene sequences.ACC synthase and ACC oxidase are two key enzymes of ethylene synthesis.The five homologous genes have differentially expression between two transcript samples,and involve in the regulation of ethylene biosynthesis which appears in pathway of methionine metabolism.A comparison of their nucleotide sequences in NCBI showed,they have more than80%homology with other species ACC synthase and ACC oxidase homologous gene.That means,there may be a close relationship between these five genes and mango soft nose disease.4.Five pectate lyase homologous genes have significant and differential expression between two samples, and involve in the poly(1,4-α-galacturonate) degradation process which appears in metabolic pathway of pentose and glucuronate interconversions.Their nucleotide sequences were submitted to NCBI database for homology comparison.They have more than70%homology with other species pectate lyase homologous gene.It could speculate that these five gene sequences may be associated with the pathogenesis of mango soft nose disease.5. It speculate that ACC synthase homologous gene、ACC oxidase homologous gene and pectate lyase homologous gene were regulatory relationships in the pathogenesis of soft nose disease. The occurrence of the mango soft nose should be the results of regulation and control of multiple genes..