ORIGINAL ARTICLE Chlorophyll fluorescence lifetime imaging provides new insight into the chlorosis induced by plant virus infection Rong Lei 1 • Hongshan Jiang 1 • Fan Hu 1 • Jin Yan 1 • Shuifang Zhu 1 Received: 10 October 2016 / Accepted: 15 November 2016 Ó Springer-Verlag Berlin Heidelberg 2016 Abstract Key message Leaf chlorosis induced by plant virus infection has a short fluorescence lifetime, which reflects damaged photosynthetic complexes and degraded chloroplasts. Abstract Plant viruses often induce chlorosis and necrosis, which are intimately related to photosynthetic functions. Chlorophyll fluorescence lifetime measurement is a valu- able noninvasive tool for analyzing photosynthetic pro- cesses and is a sensitive indicator of the environment surrounding the fluorescent molecules. In this study, our central goal was to explore the effect of viral infection on photosynthesis by employing chlorophyll fluorescence lifetime imaging (FLIM), steady-state fluorescence, non- photochemical quenching (NPQ), transmission electron microscopy (TEM), and pigment analysis. The data indi- cated that the chlorophyll fluorescence lifetime of chlorotic leaves was significantly shorter than that of healthy control leaves, and the fitted short lifetime component of chloro- phyll fluorescence of chlorotic leaves was dominant. This dominant short lifetime component may result from dam- age to the structure of thylakoid, which was confirmed by TEM. The NPQ value of chlorotic leaves was slightly higher than that of healthy green leaves, which can be explained by increased neoxanthin, lutein and violaxanthin content relative to chlorophyll a. The difference in NPQ is slight, but FLIM can provide simple and direct character- ization of PSII structure and photosynthetic function. Therefore, this technique shows great potential as a simple and rapid method for studying mechanisms of plant virus infection. Keywords Plant virus Á Photosynthesis Á Chlorophyll fluorescence lifetime imaging microscope Á Time-correlated single-photon counting (TCSPC) Á Non-photochemical quenching (NPQ) Introduction Plant viruses are widespread, economically important pathogens that can cause severe symptoms, such as mosaic, chlorotic, or necrotic patterns; mottling; leaf rolling; and developmental abnormalities (Doke et al. 1995; Riedle- Bauer 2000; Allan et al. 2001; Clarke et al. 2002; Her- nandez et al. 2004, 2006). Studies on different plant virus systems have indicated that photosynthetic processes in the chloroplasts of infected plants can be greatly affected (Goodman et al. 1986; Zaitlin and Hull 1987; Kyselakova et al. 2011), including decreased photosynthetic electron transport rates (Naidu et al. 1984; Reinero and Beachy 1989; Ryslava et al. 2003; Chen et al. 2007; Song et al. 2009) and reduced photosynthetic efficiency (Funayama et al. 1997). Chlorosis is a severe symptom induced by some plant viruses, such as the M strain of cucumber mosaic virus (M-CMV) (Lu et al. 2012; Lei et al. 2016), which induces extreme yellow/white chlorosis in Nicotiana Communicated by Y-Il Park. Electronic supplementary material The online version of this article (doi:10.1007/s00299-016-2083-y) contains supplementary material, which is available to authorized users. & Shuifang Zhu zhusf@caiq.gov.cn Rong Lei leir@caiq.gov.cn 1 Institute of Plant Quarantine of China, Chinese Academy of Inspection and Quarantine, Beijing 100762, China 123 Plant Cell Rep DOI 10.1007/s00299-016-2083-y