Li Qin, Yao Junfei, Zheng Wei, Wang Jialu, Liao Ling, Sun Guochao, Wang Xun, Deng Honghong, Zhang Mingfei, Wang Zhihui, Xiong Bo
College of Horticulture, Sichuan Agricultural University, Chengdu, China.
Front Plant Sci. 2023 Jul 3;14:1218426. doi: 10.3389/fpls.2023.1218426. eCollection 2023.
Citrus cultivation involves the widespread practice of grafting, which has a significant impact on citrus development and fruit quality and yield. However, understanding the effect of flavonoid compounds after different rootstock grafting have been limited. Flavonoid compounds, found at the highest levels in citrus peels, contribute to improving fruit quality and nutritional value. In this study, scion-rootstock interaction was investigated at various developmental stages when sweet orange 'Newhall' was hetero-grafted with two commonly used rootstocks (). Physiological index detection showed a higher concentration of total flavonoid content in peels of sweet orange 'Newhall' grafted on (ct) than (cj). Further metabolomic analysis identified 703 flavonoid compounds, including flavones, flavonols, and flavanones. Out of the 25 flavonoids affected by different rootstock grafting and developmental stages, most were flavones. Transcriptomic analysis identified 8,562 differentially expressed genes (DEGs). Co-expression and Pearson's correlation analysis discovered six hub structure genes and 19 transcription factors (TFs) that affected flavonoid biosynthesis. In addition to increasing the transcript levels of genes that synthesize flavones, flavonols, and flavanones, the scion-rootstock interaction also affected the expression of many TFs. Taken together, our findings suggested that hetero-grafting could promote the accumulation of flavonoid compounds in citrus peels during the development stages. These results offered fresh perspectives on grafting's application usefulness and the enhancement of the accumulation of nutritive flavonoid components by grafting in citrus.
柑橘栽培涉及广泛的嫁接实践，这对柑橘的发育、果实品质和产量有重大影响。然而，对于不同砧木嫁接后类黄酮化合物的作用了解有限。类黄酮化合物在柑橘果皮中含量最高，有助于提高果实品质和营养价值。在本研究中，当甜橙‘纽荷尔’与两种常用砧木进行异砧嫁接时，在不同发育阶段研究了接穗 - 砧木相互作用。生理指标检测表明，嫁接在（ct）上的甜橙‘纽荷尔’果皮中总黄酮含量浓度高于嫁接在（cj）上的。进一步的代谢组学分析鉴定出703种黄酮类化合物，包括黄酮、黄酮醇和黄烷酮。在受不同砧木嫁接和发育阶段影响的25种黄酮类化合物中，大多数是黄酮。转录组分析鉴定出8562个差异表达基因（DEG）。共表达和皮尔逊相关性分析发现了6个影响类黄酮生物合成的核心结构基因和19个转录因子（TF）。除了增加合成黄酮、黄酮醇和黄烷酮的基因的转录水平外，接穗 - 砧木相互作用还影响了许多转录因子的表达。综上所述，我们的研究结果表明，异砧嫁接可以促进柑橘发育阶段果皮中类黄酮化合物的积累。这些结果为嫁接的应用价值以及通过嫁接提高柑橘中营养性黄酮类成分的积累提供了新的视角。
