Nitric Oxide Participates in Aluminum-Stress-Induced Pollen Tube Growth Inhibition in Tea (Camelliasinensis) by Regulating CsALMTs.

Nitric oxide (NO), as a signal molecule, is involved in the mediation of heavy-metal-stress-induced physiological responses in plants. In this study, we investigated the effect of NO on Camellia sinensis pollen tubes exposed to aluminum (Al) stress. Exogenous application of the NO donor decreased the pollen germination rate and pollen tube length and increased the malondialdehyde (MDA) content and antioxidant enzyme activities under Al stress. Simultaneously, the NO donor effectively increased NO content in pollen tube of C. sinensis under Al stress and could aggravate the damage of Al3+ to C. sinensis pollen tubes by promoting the uptake of Al3+. In addition, application of the NO-specific scavenger significantly alleviated stress damage in C. sinensis pollen tube under Al stress. Moreover, 18 CsALMT members from a key Al-transporting gene family were identified, which could be divided into four subclasses. Pearson correlation analysis showed the expression level of CsALMT8 showed significant positive correlation with the Al3+ concentration gradient and NO levels, but a significant negative correlation with pollen germination rate and pollen tube length. The expression level of CsALMT5 was negatively correlated with the Al3+ concentration gradient and NO level, and positively correlated with pollen germination rate and pollen tube length. The expression level of CsALMT17 showed a significant negative correlation with Al3+ concentration and NO content in pollen tubes, but significant positive correlation with pollen germination rate and pollen tube length. In conclusion, a complex signal network regulated by NO-mediated CsALMTs revealed that CsALMT8 was regulated by environmental Al3+ and NO to assist Al3+ entry into pollen tubes; CsALMT5 might be influenced by the Al3+ signal, stimulate malate efflux in vacuoles and chelate with Al3+ to detoxify Al in C. sinensis pollen tube.

A novel pyridinium-based fluorescent probe for ratiometric detection of peroxynitrite in mitochondria.

Peroxynitrite (ONOO-) is a primary kind of reactive oxygen species. Excessive ONOO- can induce oxidative damage to biomolecules and further results in various diseases. So, quantitative monitoring ONOO- with excellent selectivity and sensitivity is imperative for elucidating its role in biological processes. In this study, a novel pyridinium fluorescent ONOO- probe (CPC) has been constructed base on ICT-modulated by combining coumarin fluorophore and diphenylphosphinate recognition group. The fluorescence response of CPC for ONOO- is realized via the removal of diphenylphosphinate group. The probe CPC shows prominent features for detection of ONOO- including fast response rate (within 3 min), excellent selectivity and sensitivity, distinct colorimetric (red to green), and a large emission wavelength shift (105 nm). The emission intensity ration (I538/I643) exhibits 153-fold enhancement along with the increasing ONOO- and the detection limit is as low as 1.60 × 10-8 M. These good response properties make CPC possible to quantitative detection of ONOO- concentration. By using the strategy, the ratiometric CPC has been employed to detection of mitochondrial ONOO- in live cell successfully.

A ratiometric fluorescent probe for visualization of thiophenol and its applications.

Thiophenol has a broad application in agriculture and industry. However, thiophenol can harm to the environment and health for its high toxicity. Developing an effective method for detection of thiophenol in the field of environmental and biology is valuable. In this work, we construct a reaction-based ratiometric fluorescent probe (E)-4-(2-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)vinyl)-1-(4-(2,4-dinitrophenoxy)benzyl)pyridin-1-ium bromide (DCVP-DNP) for probing thiophenol in environment and cells by employing (E)-7-(diethylamino)-3-(2-(pyridin-4-yl)vinyl)-2H-chromen-2-one (DCVP) as the fluorophore and 2,4-dinitrophenyl (DNP) ether as the recognition group for the first time. The probe has high selectivity for thiophenol though thiophenol-triggered nucleophilic substitution reaction. In addition, the ratio of emission intensities of the probe has linearly with thiophenol concentration in the range of 0-65 µM and the detection limit of thiophenol is as low as 4.8 × 10-8 M. Moreover, the probe can not only be applied for detection of thiophenol in water samples, but also image thiophenol in living cells, suggesting its potential application in environment and biological system.

A fluorescent sensor for fast detection of peroxynitrite by removing of C=N in a benzothiazole derivative.

A simple structured reaction-based probe for peroxynitrite (ONOO-) was developed by using benzothiazole hydrazone base of the excited-state intramolecular proton transfer (ESIPT) dye. It was constructed from 2-hydrazinylpyridine and 3-(benzo[d]thiazol-2-yl)-2-hydroxy-5-methylbenzaldehyde which possesses itself weak fluorescence and displayed prominent fluorescence response towards ONOO- by oxidizes the C=N bond to an aldehyde in aqueous solution. The probe exhibited excellent selectivity and high sensivity towards ONOO- with a low dectection limit of 5.8 × 10-8 M in physiological condition. Moreover, the probe could realize fast recognition to ONOO- in as short as 60 s. In addition, the probe was also successfully used for living cell imaging.