Lu Yuan, Yu Yao, Xuan Yanfang, Kari Ayiguli, Yang Caixia, Wang Chenyu, Zhang Chao, Gu Wei, Wang Hui, Hu Yingxiong, Sun Pingdong, Guan Yuan, Si Wenshuai, Bai Bing, Zhang Xuecai, Xu Yunbi, Prasanna Boddupalli M, Shi Biao, Zheng Hongjian
Crop Breeding and Cultivation Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai, China.
CIMMYT-China Specialty Maize Research Center, Shanghai Academy of Agricultural Sciences, Shanghai, China.
Front Plant Sci. 2023 Aug 15;14:1203284. doi: 10.3389/fpls.2023.1203284. eCollection 2023.
Waxy maize, mainly consumed at the immature stage, is a staple and vegetable food in Asia. The pigmentation in the kernel of purple waxy maize enhances its nutritional and market values. Light, a critical environmental factor, affects anthocyanin biosynthesis and results in pigmentation in different parts of plants, including in the kernel. SWL502 is a light-sensitive waxy maize inbred line with purple kernel color, but the regulatory mechanism of pigmentation in the kernel resulting in purple color is still unknown.
In this study, cyanidin, peonidin, and pelargonidin were identified as the main anthocyanin components in SWL502, evaluated by the ultra-performance liquid chromatography (UPLC) method. Investigation of pigment accumulation in the kernel of SWL502 was performed at 12, 17, and 22 days after pollination (DAP) under both dark and light treatment conditions via transcriptome and metabolome analyses.
Dark treatment affected genes and metabolites associated with metabolic pathways of amino acid, carbohydrate, lipid, and galactose, biosynthesis of phenylpropanoid and terpenoid backbone, and ABC transporters. The expression of anthocyanin biosynthesis genes, such as , , , and , was reduced under dark treatment. Dynamic changes were identified in genes and metabolites by time-series analysis. The genes and metabolites involved in photosynthesis and purine metabolism were altered in light treatment, and the expression of genes and metabolites associated with carotenoid biosynthesis, sphingolipid metabolism, MAPK signaling pathway, and plant hormone signal transduction pathway were induced by dark treatment. Light treatment increased the expression level of major transcription factors such as , , , , , , , and in purple waxy maize kernels, while dark treatment greatly promoted the expression level of transcription factors , , , and .
This study is the first report to investigate the effects of light on waxy maize kernel pigmentation and the underlying mechanism at both transcriptome and metabolome levels, and the results from this study are valuable for future research to better understand the effects of light on the regulation of plant growth.
糯玉米主要在未成熟阶段食用，是亚洲的一种主食和蔬菜。紫糯玉米籽粒中的色素沉着提高了其营养价值和市场价值。光作为一个关键的环境因素，影响花青素的生物合成，并导致植物不同部位（包括籽粒）出现色素沉着。SWL502是一个具有紫色籽粒颜色的光敏感糯玉米自交系，但导致籽粒呈现紫色的色素沉着调控机制仍不清楚。
在本研究中，通过超高效液相色谱（UPLC）法鉴定出矢车菊素、芍药色素和天竺葵素是SWL502中的主要花青素成分。通过转录组和代谢组分析，在授粉后12、17和22天（DAP），在黑暗和光照处理条件下对SWL502籽粒中的色素积累进行了研究。
黑暗处理影响了与氨基酸、碳水化合物、脂质和半乳糖代谢途径、苯丙烷类和萜类骨架生物合成以及ABC转运蛋白相关的基因和代谢物。在黑暗处理下，花青素生物合成基因如 、 、 和 的表达降低。通过时间序列分析确定了基因和代谢物的动态变化。光照处理改变了参与光合作用和嘌呤代谢的基因和代谢物，黑暗处理诱导了与类胡萝卜素生物合成、鞘脂代谢、MAPK信号通路和植物激素信号转导通路相关的基因和代谢物的表达。光照处理提高了紫糯玉米籽粒中主要转录因子如 、 、 、 、 、 、 和 的表达水平，而黑暗处理则极大地促进了转录因子 、 、 和 的表达水平。
本研究首次在转录组和代谢组水平上研究了光对糯玉米籽粒色素沉着的影响及其潜在机制，本研究结果对于未来更好地理解光对植物生长调控的影响的研究具有重要价值。
