Hormonal Mediation of the Light Control of Internode        Extension Using Pea Genotypes
{'Code': '08090100', 'Directorate': {'LongName': 'Direct For Biological Sciences'}, 'Division': {'LongName': 'Division Of Integrative Organismal Systems'}}
{'SignBlockName': 'Judith Plesset'}
Light causes a pronounced decrease in stem growth rate.  Dr.                Davies proposes to investigate the kinetics of hormonal changes                 in relation to the growth kinetics following the transition from                dark to red light in order to determine to what extent, and in                  what manner, changes in endogenous hormones may mediate light-                  induced  changes in stem growth rate.  Red light will be used to                reduce the complexity inherent in white light.  Dr. Davies will                 use a range of pea length genotypes whose gibberellin (GA)                      content is known.  All of the genotypes grow faster in the dark                 than in the light but vary in the proportional reduction in                     their growth rate in the light.  In some genotypes GAs are absent               yet they are tall; in such plants he finds a very high                          indoleacetic acid (IAA) level.  He has considerable evidence that               GA may act via the induction of tryptophan racemase causing the                 production of D-tryptophan, which is then the precursor of IAA.                 The kinetics of growth are recorded by position transducers under               darkness and illumination of known spectral composition, and                    following hormone and inhibitor applications.  GAs, IAA and IAA                 conjugates, will be measured by gas chromatography-mass                         spectrometry and components of the IAA synthesis pathway assayed.               This will show the point(s) in the GA and IAA metabolic pathways                at which light acts, and whether a light induced change in GA                   levels in fact operates by altering the level of IAA.                           %%%                                                                                 Light causes a decrease in the growth of stems of plants                    previously grown in the dark.  The mechanism by which this occurs               is unknown.  One possibility is that light alters the level of                  plant hormones.  To determine whether plant hormones are involved               one need to know the rate at which light induces a decrease in                  growth, and then examine the changes in the internal levels of                  the plant hormones to see if they change at the same time. Dr.                  Davies will measure the rate of growth change and hormonal                      content in pea varieties which have different stem lengths. The                 difference in stem lengths is genetically controlled, and has                   been shown to be due to changes in levels or responsiveness to                  plant hormones called gibberellins.  There is also evidence that                this hormone may interact in some way in the synthesis of                       another hormone, indoleacetic acid.  Dr. Davies will measure the                changes in the internal levels of gibberellin and indole acetic                 acid to determine if and how light causes a decrease in stem                    growth. This will improve our knowledge of how plants grow.
{'FirstName': 'Peter', 'LastName': 'Davies', 'EmailAddress': 'pjd2@cornell.edu', 'StartDate': '06/01/1988', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'Cornell University', 'CityName': 'Ithaca', 'ZipCode': '148502820', 'PhoneNumber': '6072555014', 'StreetAddress': '373 Pine Tree Road', 'CountryName': 'United States', 'StateName': 'New York', 'StateCode': 'NY'}
{'Code': '1111', 'Text': 'DEVELOPMENTAL SYSTEMS CLUSTER'}
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1988&All=true', 'xml': '8801880.xml'}