The WRKY17-WRKY50 complex modulates anthocyanin biosynthesis to improve drought tolerance in apple.

Drought stress is increasing worldwide due to global warming, which severely reduces apple (Malus domestica) yield. Clarifying the basis of drought tolerance in apple could accelerate the molecular breeding of drought-tolerant cultivars to maintain apple production. We identified a transcription factor MdWRKY50 by yeast two-hybrid (Y2H) assays as an interactor of the drought-tolerant protein MdWRKY17, and confirmed their interaction by bimolecular fluorescence complementation (BiFC) and pull-down assays. MdWRKY50 was induced by drought and when overexpressed in apple, conferred transgenic apple plants enhanced drought tolerance by directly binding to the promoter of anthocyanin synthetic gene Chalcone synthase (MdCHS) to upregulate its expression for higher anthocyanin. Increased anthocyanin relieves apple plants from oxidative damage under drought stress. MdWRKY50 RNA-interference transgenic apple plants showed opposite phenotypes. The dimerization of MdWRKY50 with mutated MdWRKY17DP mimicking drought-induced phosphorylation by the mitogen-activated protein kinase kinase 2 (MEK2)-MPK6 cascade, compared with MdWRKY17AP and MdWRKY17, further promoted anthocyanin biosynthesis, suggesting dimerization with MdWRKY17 makes MdWRKY50 more powerful in promoting anthocyanin biosynthesis under drought stress. Taken together, we isolated an entire MEK2-MAPK6-MdWRKY17-MdWRKY50-MdCHS pathway for drought tolerance and generated transgenic apple germplasm with enhanced drought tolerance and higher anthocyanin levels.

MdMPK3 and MdMPK6 fine-tune MdWRKY17-mediated transcriptional activation of the melatonin biosynthesis gene MdASMT7.

Melatonin (N-acetyl-5-methoxytryptamine) is a potent reactive oxygen species (ROS) scavenger that increases the biotic and abiotic stress tolerance in plants. The signaling and regulation pathways of melatonin in plants remain elusive. Here, we report that transgenic apple (Malus domestica) plants overexpressing the transcription factor gene, MdWRKY17, have higher melatonin contents and lower ROS levels than those of control, while the MdWRKY17 RNA interference (RNAi) lines show the reversed phenotype. The binding of MdWRKY17 to N-acetylserotonin O-methyltransferase7 (MdASMT7) directly promotes the MdASMT7 expression in the in vitro and in vivo. MdASMT7 is a melatonin synthase that localizes to the plasma membrane. MdASMT7 overexpression rescued the lower melatonin contents of MdWRKY17-RNAi lines, confirming the role of MdWRKY17-MdASMT7 module in melatonin biosynthesis in apple. Furthermore, melatonin treatment activated the mitogen-activated kinases (MPKs) MdMPK3 and MdMPK6, which phosphorylate MdWRKY17 to promote transcriptional activation of MdASMT7. RNAi-mediated silencing of MdMPK3/6 decreases MdASMT7 expression in transgenic apple plants overexpressing MdWRKY17, which further confirms MdMPK3/6 fine-tunes MdWRKY17-mediated MdASMT7 transcription. This also forms a positive loop that melatonin activates MdMPK3/6 and thus accelerates the biosynthesis of itself via triggering MdMPK3/6-MdWRKY17-MdASMT7 pathway. This novel melatonin regulatory pathway not only have dissected the molecular mechanisms of melatonin biosynthesis but also provided an alternative approach for generating transgenic melatonin-rich apples which may benefits to human health.

[Precise Temperature Measurement with Imaged Spectral Technique].

A new method for temperature measurement is established based on the gray-body radiation, which can not only determine the real-time temperature of thermal source, but also conduct non-contacted temperature measurement with high precision. First, a wide-band emission spectrum of the given radiation source is measured precisely with a multi-channel CCD image spectrometer, which is served as its spectral fingerprints for establishing a gray-body radiation model; Secondly, the coefficients introduced in the gray-body radiation model are determined by fitting the measured emission spectrum; Finally, a combination of spectroscopic technique and the gray-body radiation model is employed to measure any temperature of the given radiation source. Having tested on both types of radiation sources, with and without a flame, the present work has demonstrated that the imaged spectral approach mentioned above can be utilized as a real-time, high precision and non-contacted technique for temperature measurement.

[Study on Raman Spectra of Some Clinical Medicine].

Aiming at the shortage of the Raman spectra of drugs and the current situation of drug testing, we have applied Raman spectroscopic technique to several kinds of medicine, such as antibiotics, antihistamine, hemocoagulase and antiemetics. The spectral properties for the samples with high Raman activity are investigated by observing their Raman spectra to yield the shift, intensity, and line width of the Raman peaks, as well as the line shape of Raman envelope. For those samples with weak Raman activity or complex structures that are hard to be identified, we have also made some tentative measurements or raise some suggestions for future measurement. Comparing the similarities or differences among many Raman spectra of drugs, it is evident that drugs with small molecule have apparent spectral characteristics, by which to recognize them is very feasible, while those with large molecule usually have weak peaks or complex envelope in their spectra, leading to a difficult recognition and uncertain peak positions. This work not only proposes to identify chemical ingredients of drugs by observing and analyzing their Raman spectra, but also provides experimental evidences for medical workers doing so. The present results lay the foundation for establish the database of Raman spectra for drugs, and point out the prospect for rapid identification and detection of drugs, promoting the application of Raman spectroscopy technology on drug detection to a certain extent.

[Study on Raman Spectra of Some Animal and Plant Oils].

The spectral characteristics of different kinds of oil, either from plant seeds or animal fat, were studied with Raman spectroscopy. The experimental data were processed with the adaptive iteratively reweighted penalized least squares method to realize baseline correction, and provide evident information about their microscopic world. The spectra were analyzed and compared with each other in three parts: the Raman spectra comparison among different samples of plant oils, the analysis of the animal fat and the comparison between plant oils and the animal fat. The differences among the oils were observed in the analysis, including Raman shift and Raman intensity differences. This study not only yields the spectral basis for distinguishing or recognizing the different edible oils, but also confirms that Raman spectroscopy is an effective tool for identifying different oils.