Liriodendron chinense × tulipifera black spot is a newly discovered disease that causes yellowing and early shedding of leaves, affecting the growth of Liriodendron trees, and significantly reducing their ornamental value as a garden species. The pathogen responsible for this disease, and how it can be prevented and controlled, are not clear. In this study, the occurrence of this disease was first investigated according to Koch’s postulates, and the primary pathogens causing Liriodendron black spot were determined to be Colletotrichum gloeosporioides and Alternaria alternata. Biocontrol strains antagonistic to these two pathogens were then screened from the leaf microorganisms of L. chinense × tulipifera, and a preliminary investigation of the biological control of Liriodendron black spot was performed. Through the screening of antagonistic microorganisms on the leaf surface of L. chinense × tulipifera, the strain Trichoderma koningiopsis T2, which displayed strong antagonism against C. gloeosporioides and A. alternata, was obtained. The T2 strain could inhibit the growth of the two pathogens via three mechanisms: hyperparasitism, volatile and nonvolatile metabolite production, and environmental acidification. The biocontrol experiments in the greenhouse and field showed that initial spraying with a T. koningiopsis T2 spore suspension followed by the two pathogens resulted in the lowest disease incidence. These results confirmed the black spot pathogens of L. chinense × tulipifera, clarified the antagonistic mechanism of T. koningiopsis T2 against the two pathogens, and provided a theoretical basis and technical support for the biological control of the disease.

Time-lapse single cell imaging by microscopy can provide precise cell information such as the cell size, the cell cycle duration, protein localization and protein expression level. Usually, a microfluidic system is needed for these measurements in order to provide a constant culture environment and confine the cells so that they grow in a monolayer. However, complex connections are required between the channels inside the chip and the outside media, and a complex procedure is needed for loading of cells, thereby making this type of system unsuitable for application in high-throughput single cell scanning experiments. Here we provide a novel and easily operated pump-free multi-well-based microfluidic system which enables the high-throughput loading of many different budding yeast strains into monolayer growth conditions just by use of a multi-channel pipette. Wild type budding yeast (Saccharomyces cerevisiae) and 62 different budding yeast size control relative gene deletion strains were chosen for scanning. We obtained normalized statistical results for the mother cell doubling time, daughter cell doubling time, mother cell size and daughter cell size of different gene deletion strains relative to the corresponding parameters of the wild type cells. Meanwhile, we compared the typical cell morphology of different strains and analyzed the relationship between the cell genotype and phenotype. This method which can be easily used in a normal biology lab may help researchers who need to carry out the high-throughput scanning of cell morphology and growth.

In the present study,we develop an efficient method to be used to examine recombination efficiency of transgenic plantlet.Two constructs,one containing Cre recombinase under the control of 35 S promoter (p35S/Cre) and the other containing a \%uidA\% gene driven by 35 S promoter flanked by loxP site (loxP/35S/GUS/loxP),were simultaneously introduced into tobacco by cotransformation method.The results show that Cre loxP system can precisely and efficiently direct deletion of transgene based on Gus assay,PCR analysis and sequence of recombination DNA fragment,but also find that incomplete deletion exist in partial plant.

To engineer crop disease resistance by utilizing natural defense mechanism that was expressed in the incompatible host-pathogen interactions is expected to result in a durable and broad-spectrum resistance. In order to prove this viewpoint, we amplified the coding region of the glucose oxidase (GO) gene fromAspergillus niger via PCR and fused it to the pathogen-inducible promoter, Prp1-1. The chimeric gene was cloned into a plant expression vector and conjugated intoAgrobacterium. Twenty-three transgenic potato plants were obtained byAgrobacterium-mediated transformation. The integration ofGO gene was confirmed by Southern hybridization and theGO gene expression was identified with Kl-starch color reaction.Phytophthora infestans inoculation revealed that the expression of the chimeric transgene was induced by pathogen infection. Most of the transgenic plants exhibited various degrees of enhanced disease resistance. Four of them had lesion sizes reduced to less than half of the non-transgenic controls. One plant showed disease resistance of the hypersensitive response. These results testified the feasibility of our strategy of expressingGO transgene under the control of the disease-inducible promoter in engineering crop disease resistance.