Re-Sequencing and Transcriptomic Analysis Reveal Differences in Nitrite Reductase in Jujube Fruit (Ziziphus Jujube)

BackgroundJujube is one of the characteristic fruit tree species in China. ‘Linhuang No. 1’, a cracking-resistant cultivar, and ‘Muzao’, a cracking-susceptible cultivar, were selected as materials by previous study. Whole-genome re-sequencing and transcriptome of ‘Linhuang No. 1’ and ‘Muzao’ allow the screening out of differently expressed genes with different gene structures between them. It could be helpful in explaining divergence/similarity between the two cultivars. ResultsThere are 664,129 mutation sites between ‘Linhuang No. 1’ and ‘Muzao’ by re-sequencing. To determine the genetic relationship of ‘Linhuang 1’, ‘Muzao’ and reference genome ‘Dongzao’, the characteristic mutation sites were analyzed by principal component analysis. The genetic relationship between ‘Linhuang No. 1’ and ‘Muzao’ was closer than that with ‘Dongzao’. 19 differentially expressed genes were screened by combining the transcriptomics with re-sequencing analysis. LOC107427052 (encoding nitrite reductase) was determined by KEGG enrichment analysis for further study. The large base insertion was not in the domain region of the LOC107427052 gene CDS region. As verified by the finding that the base insertion did not affect protein translation. LOC107427052 gene expression levels, the nitrite reductase activities and the nitrite content of ‘Muzao’ were significantly higher than those of ‘Linhuang No. 1’ at young fruit stage. There was no significant difference in the product ammonia of nitrite reductase between the two varieties. ConclusionsOur study has laid a foundation for the analysis of genetic information and the comparative nitrite metabolism of ‘Linhuang No. 1’ and ‘Muzao’.