Transcriptome analysis of citrus rustmite damage to the peel of Orah fruits

 Abstract:【Objective】In order to reveal the molecular mechanism of citrus rust mite damage to citrus fruits, the related response genes were screened, and the varieties resistant to citrus rust mite were im- proved by using the related resistance gene resources, so as to breed new varieties with stronger resis- tance to citrus rust mite【. Methods】Sixty citrus rust mites were inoculated on the same size fruits with- out diseases and insect pests in this experiment. During the experiment, no other diseases and insect pests were found. Three, five, seven and nine days after inoculation, three replicates of each sample were taken. 5 g peel with control (CK) and citrus rust mites groups (WG) were rinsed with sterile water, wrapped with tin foil, and treated with liquid nitrogen before they were put in the refrigerator at -80 °Cfor standby. The two-way transcriptome sequencing was performed on novaseq6000 platform, and the bioinformatics correlation analysis was carried out.【Results】A total of 55.63 gb clean bases were ob- tained. After removing low-quality bases and linker sequences, 42 115 939, 45 501 683, 58 118 008 and 40 715 511 clean reads were obtained from CK3, CK5, CK7 and CK9, and 46 807 089, 49 185 798, 44 437 798 and 44 035 730 clean reads were obtained from WG3d, WG5d, WG7d and WG9d, respec- tively. The number of up-regulated differentially expressed genes was 2764, 1812, 3217 and 2778 in treatment 3、5、7、9 d，and the number of down regulated differentially expressed genes was 3036,1387, 3350 and 2347 respectively. The results of GO enrichment analysis showed that the DEGs of 3 d were mainly enriched in the process of organic nitrogen metabolism, biological process, metabolic pro- cess and redox; the cellular components were enriched in ribosome, ribonucleoprotein complex and mo- lecular complex; the molecular functions were mainly enriched in the structural composition, structural molecular activity and oxidoreductase of ribosome. In addition, the catalytic activity and other functions were also found. The DEGs of 5 d were mainly enriched in the redox process, monomer metabolism pro- cess, biological process, metabolic process and other processes in the biological process; the molecular functions were mainly enriched in heme binding, tetrapyrrole binding, iron ion binding, oxidoreductase activity, electron carrier activity, catalytic activity and so on. The DEGs of 7 d were mainly enriched in the metabolic process, biological process, redox process, organic nitrogen compounds metabolic pro- cess, organic nitrogen compounds biosynthesis process and so on; the cell components were enriched in the cytoplasmic part, ribonucleoprotein complex, ribosome, polymer complex, cytoplasm and so on; the molecular functions were mainly enriched in the catalytic activity, oxidation activity, reductase activity and so on. The DEGs of 9 d were mainly enriched in the biological process, metabolic process and single organism metabolic process, and the molecular function was mainly enriched in the activity of oxidore- ductase and catalytic activity. KEGG annotation analysis showed that the DEGs of 3 d were mainly annotated to vitamin B6 metabolism, biosynthesis of stilbene, diarylheptane and gingerol, photosynthesis, phenylpropanoid biosynthesis, pentose phosphate and other pathways. The DEGs of 5 d were mainly en- riched in vitamin B6 metabolism, biosynthesis of stilbene, diarylheptane and gingerol, selenium com- plex metabolism, photosynthesis antennae, photosynthesis, phenylalanine biosynthesis, phenylalanine, tyrosine and tryptophan biosynthesis. The DEGs of 7 d were mainly enriched in the biosynthesis of stil- bene, diarylheptane and gingerol, ribosome, endoplasmic reticulum protein processing, proteolytic en- zyme complex, porphyrin and chlorophyll metabolism, photosynthesis antennae, photosynthesis, phenyl- propanoid biosynthesis, pentose phosphate pathway, oxidative phosphorylation and other pathways. The DEGs of 9 d were mainly enriched in the biosynthesis of stilbene, diarylheptane and gingerol, photosyn- thesis antennae, photosynthesis, phenylalanine biosynthesis, phenylalanine, tyrosine and tryptophan bio- synthesis pathways.【Conclusion】High throughput transcriptome sequencing technology was used to se- quence and analyze Orah fruits damaged by citrus rust mite, and multiple differentially expressed genes were screened, which were involved in plant hormone signal transduction, plant pathogen interaction pathway, flavonoid biosynthesis, phenylalanine metabolism, pentose phosphate and other pathways in different damage periods. The research on the molecular mechanism of Orah responding to the damage of citrus rust mite can provide not only abundant gene resources, but also a theoretical basis for the re- search on the gene regulatory network of Citrus germplasm resources under the mite damage conditions.