Deng Yunquan, Feng Zhongtao, Yuan Fang, Guo Jianrong, Suo Shanshan, Wang Baoshan
Key Laboratory of Plant Stress Research, College of Life Science, Shandong Normal University, Jinan 250014, Shandong, People's Republic of China.
Plant Physiol Biochem. 2015 Dec;97:20-7. doi: 10.1016/j.plaphy.2015.09.007. Epub 2015 Sep 10.
Limonium bicolor is a typical recretohalophyte with salt glands for the secretion of excess salts into the environment. We observed that L. bicolor salt glands showed obvious blue autofluorescence under UV excitation (330-380 nm). The aim of the present study was to identify and clarify a role for this autofluorescent substance in salt secretion. Sudan IV staining showed that the autofluorescent substance was localized in the cuticle of the salt glands. Moreover, the primary autofluorescent substance was identified as ferulic acid after treatment with 0.1 M ammonium hydroxide solution, alkaline and enzymatic hydrolysis. Additional experiments using two mutants exhibiting increased (fii) and decreased (fid) salt gland fluorescence indicated that the fluorescence intensity of salt glands under UV excitation was positively correlated with the content of ferulic acid in the cuticle, strongly suggesting that the primary autofluorescent substance in the salt glands was ferulic acid. Salt gland secretion was determined using leaf discs, and the results showed that the Na(+) secretion rate per single salt gland was also positively correlated with the content of ferulic acid in the cuticle, suggesting that ferulic acid in the cuticle was directly involved in salt secretion of salt gland.
二色补血草是一种典型的泌盐盐生植物，具有盐腺，可将多余盐分分泌到环境中。我们观察到，在紫外线激发（330 - 380纳米）下，二色补血草的盐腺呈现出明显的蓝色自发荧光。本研究的目的是鉴定并阐明这种自发荧光物质在盐分分泌中的作用。苏丹IV染色显示，自发荧光物质位于盐腺的角质层中。此外，在用0.1 M氢氧化铵溶液处理、进行碱性和酶水解后，主要的自发荧光物质被鉴定为阿魏酸。使用两个盐腺荧光增强（fii）和减弱（fid）的突变体进行的额外实验表明，紫外线激发下盐腺的荧光强度与角质层中阿魏酸的含量呈正相关，这强烈表明盐腺中的主要自发荧光物质是阿魏酸。使用叶盘测定盐腺分泌，结果表明单个盐腺的Na(+)分泌速率也与角质层中阿魏酸的含量呈正相关，这表明角质层中的阿魏酸直接参与盐腺的盐分分泌。
