AUTHOR=Yang Lei , Chen Yang , Wang Min , Hou Huifang , Li Shuang , Guan Ling , Yang Haijian , Wang Wu , Hong Lin 

TITLE=Metabolomic and transcriptomic analyses reveal the effects of grafting on blood orange quality

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1169220

DOI=10.3389/fpls.2023.1169220

ISSN=1664-462X

ABSTRACT=<sec><title>Introduction</title><p>Blood orange (<italic>Citrus sinensis</italic> L.) is a valuable source of nutrition because it is enriched in anthocyanins and has high organoleptic properties. Grafting is commonly used in citriculture and has crucial effects on various phenotypes of the blood orange, including its coloration, phenology, and biotic and abiotic resistance. Still, the underlying genetics and regulatory mechanisms are largely unexplored.</p></sec><sec><title>Methods</title><p>In this study, we investigated the phenotypic, metabolomic, and transcriptomic profiles at eight developmental stages of the lido blood orange cultivar (<italic>Citrus sinensis</italic> L. Osbeck cv. Lido) grafted onto two rootstocks.</p></sec><sec><title>Results and discussion</title><p>The Trifoliate orange rootstock provided the best fruit quality and flesh color for Lido blood orange. Comparative metabolomics suggested significant differences in accumulation patterns of metabolites and we identified 295 differentially accumulated metabolites. The major contributors were flavonoids, phenolic acids, lignans and coumarins, and terpenoids. Moreover, transcriptome profiling resulted in the identification of 4179 differentially expressed genes (DEGs), and 54 DEGs were associated with flavonoids and anthocyanins. Weighted gene co-expression network analysis identified major genes associated to 16 anthocyanins. Furthermore, seven transcription factors (<italic>C2H2</italic>, <italic>GANT</italic>, <italic>MYB-related</italic>, <italic>AP2/ERF</italic>, <italic>NAC</italic>, <italic>bZIP</italic>, and <italic>MYB</italic>) and five genes associated with anthocyanin synthesis pathway (<italic>CHS</italic>, <italic>F3H</italic>, <italic>UFGT</italic>, and <italic>ANS</italic>) were identified as key modulators of the anthocyanin content in lido blood orange. Overall, our results revealed the impact of rootstock on the global transcriptome and metabolome in relation to fruit quality in lido blood orange. The identified key genes and metabolites can be further utilized for the quality improvement of blood orange varieties.</p></sec>