Colored-leaf trees play a crucial role in urban greening due to their aesthetic appeal. However, traditional breeding methods combined with long growth cycle, have resulted in a limited variety of colored-leaf species, failing to meet the needs of city park construction. Molecular breeding, known for its rapid and targeted trait improvement, has become a pivotal approach for creating new ornamental tree varieties. In previous research, we identified the gene encoding chlorophyllase (CLH) as significantly upregulated expression in yellow leaves based on transcriptome sequence of the bud mutation of ‘golden-leaf poplar’ Populus deltoides Marsh. However, the molecular mechanism of CLH gene in regulating the poplar leaf color and growth is unclear, which hinders the application of poplar in landscape, forestry production and bioenergy. To determine the underlying mechanism, PdCLH-overexpression poplar (OE-44 and OE-28) and RNA interference PdCLH-expression poplars (Ri-146 and Ri-175) were obtained. Results revealed that Ri-146 and Ri-175 exhibited greener leaves and enhanced growth compared to the wide-type (WT), while overexpressed lines, OE-44 and OE-28, displayed yellower leaves with subdued growth. RNA-seq data revealed that 1682, 1175, and 550 differentially expressed genes (DEGs) existed between OE and WT, Ri and WT, OE and Ri, respectively. And these DEGs were mainly concentrated in flavonoidin-anthocyanin metabolism (PaCYP75A1, PaLAR), abscisic acid degradation (CYP707A1, CYP707A2), photosynthesis (PaFDX) and chlorophyll degradation (PaCAO), and they caused yellowing and dwarfing of overexpressed lines. Meanwhile, DEGs encoding phenolic compound biosynthesis (PaBEAT), abscisic acid degradation (CYP707A1, CYP707A4), plant hormone signaling (PaTH23, PaCYCD-3), and chlorophyll degradation (PaSGR) made interference PdCLH-expression poplars greener and more vigorous growth. These findings suggest that PdCLH has the potential to alter leaf color and enhance the growth, which will provide theoretical references and gene resources for molecular breeding on colored-leaf trees.

彩叶树因其美观而在城市绿化中发挥着至关重要的作用。但传统的养殖方式加之生长周期长，导致彩叶品种品种有限，无法满足城市公园建设的需要。分子育种以其快速、有针对性的性状改良而闻名，已成为创造新的观赏树品种的关键方法。在前期研究中，我们根据三角叶杨芽突变的转录组序列，发现编码叶绿素酶（CLH）的基因在黄叶中表达显着上调。然而，CLH基因调控杨树叶色和生长的分子机制尚不清楚，这阻碍了杨树在景观、林业生产和生物能源方面的应用。为了确定潜在机制，获得了 PdCLH 过表达杨树（OE-44 和 OE-28）和 RNA 干扰 PdCLH 表达杨树（Ri-146 和 Ri-175）。结果显示，与宽型 (WT) 相比，Ri-146 和 Ri-175 表现出更绿的叶子和增强的生长，而过表达的品系 OE-44 和 OE-28 表现出更黄的叶子且生长减弱。 RNA-seq数据显示OE和WT、Ri和WT、OE和Ri之间分别存在1682、1175和550个差异表达基因(DEG)。这些差异表达基因主要集中在黄酮花青素代谢(PaCYP75A1、PaLAR)、脱落酸降解(CYP707A1、CYP707A2)、光合作用(PaFDX)和叶绿素降解(PaCAO)等方面，引起过表达株系的黄化和矮化。 同时，编码酚类化合物生物合成（PaBEAT）、脱落酸降解（CYP707A1、CYP707A4）、植物激素信号传导（PaTH23、PaCYCD-3）和叶绿素降解（PaSGR）的DEG使干扰PdCLH表达的杨树更绿、生长更旺盛。这些研究结果表明PdCLH具有改变叶色、促进生长的潜力，为彩叶树的分子育种提供理论参考和基因资源。