Key Laboratory of State Forestry and Grassland Administration on Tropical Forestry, Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou 510520, China.
Int J Mol Sci. 2024 May 2;25(9):4974. doi: 10.3390/ijms25094974.
is highly valued for its commercial applications, with the heartwood exhibiting a range of colors from dark to light among its various clones. The underlying mechanisms contributing to this color variation, however, have not been fully elucidated. In an effort to understand the factors that influence the development of dark heartwood, a comparative analysis was conducted on the microstructure, substance composition, differential gene expression, and metabolite profiles in the sapwood (SW), transition zone (TZ), and heartwood (HW) of two distinct clones, SR14 and SR25. A microscopic examination revealed that heartwood color variations are associated with an increased substance content within the ray parenchyma cells. A substance analysis indicated that the levels of starches, sugars, and lignin were more abundant in SP compared to HW, while the concentrations of phenols, flavonoids, and terpenoids were found to be higher in HW than in SP. Notably, the dark heartwood of the SR25 clone exhibited greater quantities of phenols and flavonoids compared to the SR14 clone, suggesting that these compounds are pivotal to the color distinction of the heartwood. An integrated analysis of transcriptome and metabolomics data uncovered a significant accumulation of sinapyl alcohol, sinapoyl aldehyde, hesperetin, 2', 3, 4, 4', 6'-peptahydroxychalcone 4'-O-glucoside, homoeriodictyol, and (2S)-liquiritigenin in the heartwood of SR25, which correlates with the up-regulated expression of (..., ..., ..., ..., and ...), (..., ..., and ...), (..., ..., and ...), and (..., ..., ..., and ...) in the TZ of . . Furthermore, a marked differential expression of transcription factors (TFs), including , , , , , and , were observed to be closely linked to the phenols and flavonoids metabolites, highlighting the potential role of multiple TFs in regulating the biosynthesis of these metabolites and, consequently, influencing the color variation in the heartwood. This study facilitates molecular breeding for the accumulation of metabolites influencing the heartwood color in . , and offers new insights into the molecular mechanisms underlying heartwood formation in woody plants.
其心材颜色从深到浅变化多样，具有很高的商业价值。然而，导致这种颜色变化的潜在机制尚未完全阐明。为了了解影响深色心材发育的因素，对两个不同无性系 SR14 和 SR25 的边材 (SW)、过渡区 (TZ) 和心材 (HW) 的微观结构、物质组成、差异基因表达和代谢物谱进行了比较分析。显微镜检查表明，心材颜色的变化与射线薄壁细胞内物质含量的增加有关。物质分析表明，淀粉、糖和木质素的含量在 SP 中比 HW 中更丰富，而酚类、类黄酮和萜类化合物的浓度在 HW 中比 SP 中更高。值得注意的是，与 SR14 无性系相比，SR25 无性系的深色心材含有更多的酚类和类黄酮，表明这些化合物对心材颜色的区别至关重要。对转录组和代谢组学数据的综合分析揭示，SR25 的心材中大量积累了芥子醇、芥子醛、橙皮素、2',3,4,4',6'-五羟基查尔酮 4'-O-葡萄糖苷、高圣草素和(2S)-甘草素，这与 TZ 中 (...、...、...、...、和...)、(...、...、和...)、(...、...、和...)和(...、...、...、和...)的上调表达相关。此外，观察到转录因子 (TFs)的显著差异表达，包括、、、、、和，它们与酚类和类黄酮代谢物密切相关，强调了多个 TF 在调节这些代谢物生物合成中的潜在作用，从而影响心材的颜色变化。本研究为分子育种积累影响心材颜色的代谢物提供了帮助，为木本植物心材形成的分子机制提供了新的见解。
