Dong Xiaoyun, Huang Libin, Chen Qingsheng, Lv Yunzhou, Sun Hainan, Liang Zhenhai
Jiangsu Academy of Forestry, Nanjing 211153, China.
Plants (Basel). 2020 Feb 1;9(2):169. doi: 10.3390/plants9020169.
Shumard oak ( Buckley) is a traditional foliage plant, but little is known about its regulatory mechanism of yellow leaf coloration. Here, the yellow leaf variety of named 'Zhongshan Hongjincai' (identified as 'ZH' throughout this work) and a green leaf variety named 'Shumard oak No. 23' (identified as 'SO' throughout this work) were compared. 'ZH' had lower chlorophyll content and higher carotenoid content; photosynthetic characteristics and chlorophyll fluorescence parameters were also lower. Moreover, the mesophyll cells of 'ZH' showed reduced number of chloroplasts and some structural damage. In addition, transcriptomic analysis identified 39,962 differentially expressed genes, and their expression levels were randomly verified. Expressions of chlorophyll biosynthesis-related glumly-tRNA reductase gene and Mg-chelatase gene were decreased, while pheophorbide a oxygenase gene associated with chlorophyll degradation was up-regulated in 'ZH'. Simultaneously, carotenoid isomerase gene, z-carotene desaturase gene, violaxanthin de-epoxidase gene and zeaxanthin epoxidase gene involved in carotenoid biosynthesis were up-regulated in 'ZH'. These gene expression changes were accompanied by decreased chlorophyll content and enhanced carotenoid accumulation in 'ZH'. Consequently, changes in the ratio of carotenoids to chlorophyll could be driving the yellow leaf coloration in .
舒玛栎（Buckley）是一种传统的观叶植物，但其黄叶着色调控机制鲜为人知。在此，对名为“中山红金彩”的黄叶品种（在本研究中简称为“ZH”）和名为“舒玛栎23号”的绿叶品种（在本研究中简称为“SO”）进行了比较。“ZH”的叶绿素含量较低，类胡萝卜素含量较高；光合特性和叶绿素荧光参数也较低。此外，“ZH”的叶肉细胞显示叶绿体数量减少且有一些结构损伤。另外，转录组分析鉴定出39962个差异表达基因，并对其表达水平进行了随机验证。叶绿素生物合成相关的谷氨酰胺 - tRNA还原酶基因和镁螯合酶基因在“ZH”中的表达下降，而与叶绿素降解相关的脱镁叶绿酸a加氧酶基因在“ZH”中上调。同时，参与类胡萝卜素生物合成的类胡萝卜素异构酶基因、ζ-胡萝卜素去饱和酶基因、紫黄质脱环氧化酶基因和玉米黄质环氧化酶基因在“ZH”中上调。这些基因表达变化伴随着“ZH”中叶绿素含量降低和类胡萝卜素积累增加。因此，类胡萝卜素与叶绿素比例的变化可能是导致舒玛栎黄叶着色的原因。
