WRKY transcription factors are crucial regulatory components of plant responses to pathogen infection. In the present study, we report isolation and functional characterization of the pathogen-responsive rice WRKY30 gene, whose transcripts accumulate rapidly in response to salicylic acid (SA) and jasmonic acid (JA) treatment. Overexpression of WRKY30 in rice enhanced resistance to rice sheath blight fungus Rhizoctonia solani and blast fungus Magnaporthe grisea. The enhanced resistance in the transgenic lines overexpressing WRKY30 was associated with activated expression of JA synthesis-related genes LOX, AOS2 and pathogenesis-related (PR)3 and PR10, and increased endogenous JA accumulation under the challenge of fungal pathogens. WRKY30 was nuclear-localized and had transcriptional activation ability in yeast cells, supporting that it functions as a transcription factor. Together, our findings indicate that JA plays a crucial role in the WRKY30-mediated defense responses to fungal pathogens, and that the rice WRKY30 seems promising as an important candidate gene to improve disease resistance in rice.
Cellular images obtained by light microscopy have been analyzed qualitatively, but there is still a lack of quantitative information about the variations in cellular metabolism of selective substances. A new approach using the multispectral imaging microscope (MIM) to observe rice (Oryza sativa L.) pollen grains is reported. A liquid crystal tunable filter device was used for wavelength selection from 400 to 720 nm and a cooled two-dimensional monochrome charge coupled device for image detection. Rice pollen were stained respectively by acetocarmine, Coomassie blue, or iodine potassium-iodine, and then imaged by MIM. The images were processed by the WuDa Image Analysis System 2003 (computer software), and the transmittance spectra for pollen grain images were obtained. The statistical analysis of the transmittance data showed that the macromolecular amount (nucleic acid, protein, starch) of male-sterile line (MSL) pollen grains was less than those of the fertility-maintaining line (FML). For instance there was a significantly lower nucleic acid content in the MSL than in the FML pollen. The results revealed that pollen abortion was directly related to the diminution of intracellular substances for metabolism. Consequently, we have established a quantitative criterion to determine pollen sterility. Comparing the spectra features of the FML with the MSL, we found that certain spectra features can be used to identify various types of abortion pollens and the deficient cytoplasm of male-sterile rice. Our experimental results offer the first quantitative understanding for evaluating cell morphological structure correlated with cellular physiological status.
This paper describes a novel multispectral imaging microscope that can simultaneously record both spectral and spatial information of a sample, which can take advantage of spatial image processing and spectroscopic analysis techniques. A Liquid Crystal Tunable Filter device is used for fast wavelength selection and a cooled two-dimensional monochrome CCD for image detection. In order to acquire images that are not so dependent on imaging devices, a clever CCD exposure time control and a software based spectral and spatial calibration process is performed to diminish the influence of illumination, optic ununiformity, CCD's spectral response curve and optic throughput property. A set of multispectral image processing and analysis software package is developed, which covers not only general image processing and analysis functions, and also provides powerful analysis tools for multispectral image data, including multispectral image acquisition, illumination and system response calibration, spectral analysis and etc. The combination of spatial and spectral analysis makes it an ideal tool for the applications to biomedicine. In this paper, two applications in biomedicine are also presented. One is medical image segmentation. Using multispectral imaging techniques, a mass of experiments on both marrow bone and cervical cell images showed that our segmentation results are highly satisfactory while with low computational cost. Another is biological imaging spectroscopic analysis in the study of pollen grains in rice. The results showed that the transmittance analysis of multispectral pollen images can accurately identify the pollen abortion stage of male-sterile rice, and can easily distinguish a variety of male sterile cytoplasm.
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