ABSTRACT
Citrus reticulata Blanco 'Orah' is grown throughout southern China and provides enormous economic value. However, the agricultural industry has suffered substantial losses during recent years due to marbled fruit disease. The present study focuses on the soil bacterial communities associated with marbled fruit in 'Orah'. The agronomic traits and microbiomes of plants with normal and marbled fruit from three different orchards were compared. No significant differences were found in agronomic traits between the groups, except for higher fruit yields and higher quality of fruits in normal fruit group. Additionally, a total of 2,106,050 16S rRNA gene sequences were generated via the NovoSeq 6000. The alpha diversity index (including the Shannon and Simpson indices), Bray-Curtis similarity, and principal component analyses indicated no significant differences in microbiome diversity between normal and marbled fruit groups. For the healthy 'Orah', the most abundant associated phyla were Bacteroidetes, Firmicutes, and Proteobacteria. In comparison, Burkholderiaceae and Acidobacteria were the most abundant taxa with the marbled fruit group. In addition, the family Xanthomonadaceae and the genus Candidatus Nitrosotalea were prevalent with this group. Analysis using the Kyoto Encyclopedia of Genes and Genomes pathways showed that several pathways related to metabolism significantly differed between the groups. Thus, the present study provides valuable information regarding soil bacterial communities associated with marbled fruit in 'Orah'.
ABSTRACT
Citrus fruits exhibit vivid color and are favored extensively. However, the biochemical and molecular mechanism of Citrus Reticulata Blanco fruits coloring, especially the effect of transplantation on fruits coloring, is unclear. Herein, RNA-Seq and carotenoids profiling were applied to investigate the effect of transplantation on Orah mandarin fruits coloring. Transplantation induces fruit color shallowing, Ca2+ and ACC level declining and IAA level increasing. Transplantation induced variation in fruit skin and pulp carotenoids, mainly ß-citraurin as one of the important pigments of citrus peel. 2253 up-regulated genes, 1103 down-regulated genes in skin and 815 up-regulated genes, 534 down-regulated genes in pulp of transplanted tree fruits were identified by RNA-Seq. The DEGs involved hormone signal, carotenoids biosynthesis and TFs such as MYB and bHLH family TFs. The carotenoid cleavage dioxygenase gene (Ciclev10028113m.g) is positively correlated with ß-citraurin and regulated directly and/or indirectly by MYB1R1, PIF4, ACC and IAA. Integrative analyses revealed potential molecular insights into Orah mandarin peel color variation during transplantation.
