Guangxi South Subtropical Agricultural Research Institute, Longzhou 532415, China.
Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
Int J Mol Sci. 2024 Jun 21;25(13):6840. doi: 10.3390/ijms25136840.
Macadamia nuts are one of the most important economic food items in the world. Pericarp thickness and flavonoid composition are the key quality traits of Macadamia nuts, but the underlying mechanism of pericarp formation is still unknown. In this study, three varieties with significantly different pericarp thicknesses, namely, A38, Guire No.1, and HAES 900, at the same stage of maturity, were used for transcriptome analysis, and the results showed that there were significant differences in their gene expression profile. A total of 3837 new genes were discovered, of which 1532 were functionally annotated. The GO, COG, and KEGG analysis showed that the main categories in which there were significant differences were flavonoid biosynthesis, phenylpropanoid biosynthesis, and the cutin, suberine, and wax biosynthesis pathways. Furthermore, 63 MiMYB transcription factors were identified, and 56 R2R3-MYB transcription factors were clustered into different subgroups compared with those in Arabidopsis R2R3-MYB. Among them, the S4, S6, and S7 subgroups were involved in flavonoid biosynthesis and pericarp formation. A total of 14 s' gene expression were verified by RT-qPCR analysis. These results provide fundamental knowledge of the pericarp formation regulatory mechanism in macadamia nuts.
澳洲坚果是世界上最重要的经济食用坚果之一。种皮厚度和类黄酮组成是澳洲坚果的关键品质性状，但种皮形成的潜在机制尚不清楚。本研究以三个成熟度相同、种皮厚度差异显著的品种（A38、桂热 1 号和 HAES900）为试材进行转录组分析，结果表明，它们的基因表达谱存在显著差异。共发现 3837 个新基因，其中 1532 个具有功能注释。GO、COG 和 KEGG 分析表明，差异显著的主要类别是类黄酮生物合成、苯丙烷生物合成以及角质、栓质和蜡生物合成途径。此外，鉴定出 63 个 MiMYB 转录因子，与拟南芥 R2R3-MYB 相比，56 个 R2R3-MYB 转录因子聚类成不同的亚组。其中，S4、S6 和 S7 亚组参与类黄酮生物合成和种皮形成。通过 RT-qPCR 分析验证了 14 个 s'基因的表达。这些结果为澳洲坚果种皮形成调控机制提供了基础知识。
