page_title: Tsune Kosuge
section_title: Research
hierarchical_section_title: Tsune Kosuge / Research
context_page_description: Tsune Kosuge was an American plant pathologist and plant biochemist who researched plant–microbe interactions. He was particularly known for his work on bacterial-synthesized plant hormones in plant tumors. He was a professor in the department of plant pathology at the University of California, Davis, from 1971 until his death, serving as departmental chair.
context_section_description: In plant biochemistry, Kosuge carried out pioneering studies of the enzymes involved in secondary metabolism in plants during his PhD, researching the metabolism of coumarin in honey clover (Melilotus albus). This work included the earliest experimental demonstration of the important enzyme phenylalanine ammonia-lyase, which regulates phenylpropanoid metabolism. He subsequently continued to research how plant secondary metabolism is controlled. 
  His research in the field of plant pathology at the University of California, Davis, focused on interactions between pathogenic bacteria and their host plant. He investigated olive-knot disease, a cancer-like disease of olive trees caused by the bacterium Pseudomonas savastanoi, as well as a similar disease in oleander caused by different strains of the same bacterium. Kosuge showed the importance of indoleacetic acid (IAA), a plant hormone which is produced by P. savastanoi, in producing the tumors. In research described by the National Academy of Sciences as "meticulous", he dissected in detail the enzymes used by the bacterium to produce IAA. He also identified the series of genes encoding these enzymes and showed that they are found on the chromosome in bacterial strains that infect olive trees, but are located on a plasmid in those that infect oleander. He later showed that the genes are similar in sequence to those of Agrobacterium tumefaciens, which causes crown gall disease, and are encoded in T-DNA.
caption: Tumor caused by P. savastanoi on an olive twig
exif: {"Image Make": "Hewlett-Packard", "Image Model": "HP PhotoSmart C945 (V01.60)", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image DateTime": "2006:11:25 10:59:54", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "204", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1926", "Thumbnail JPEGInterchangeFormatLength": "3973", "EXIF ExposureTime": "29/10000", "EXIF FNumber": "4", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "100", "EXIF OECF": "[0, 2, 0, 129, 0, 0, 0, 0, 0, 8, 0, 0, 0, 16, 0, 0, 0, 24, 0, 0, ... ]", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2006:11:25 10:59:54", "EXIF DateTimeDigitized": "2006:11:25 10:59:54", "EXIF ComponentsConfiguration": "48515049", "EXIF ShutterSpeedValue": "2159/256", "EXIF ApertureValue": "985/256", "EXIF BrightnessValue": "217/32", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "14/5", "EXIF MeteringMode": "CenterWeightedAverage", "EXIF LightSource": "D55", "EXIF Flash": "Flash fired, compulsory flash mode, return light detected", "EXIF FocalLength": "38/5", "EXIF FlashPixVersion": "0010", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2608", "EXIF ExifImageLength": "1952", "EXIF FlashEnergy": "10", "EXIF FocalPlaneXResolution": "111/4000000", "EXIF FocalPlaneYResolution": "111/4000000", "EXIF FocalPlaneResolutionUnit": "3", "EXIF ExposureIndex": "100", "EXIF SensingMethod": "Not defined", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF FocalLengthIn35mmFilm": "37", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "Low gain up", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal", "EXIF DeviceSettingDescription": "[0, 1, 0, 15, 32, 32, 32, 48, 65, 48, 32, 32, 32, 55, 65, 48, 32, 32, 32, 52, ... ]", "EXIF SubjectDistanceRange": "1", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[0, 0, 0, 48]", "EXIF InteroperabilityOffset": "1802"}