75 Integrating Membrane Transport with Male Gametophyte ... - TAIR

347 Genetic Mechanisms of Glucosinolates Hydrolysis in Crucifers
Zhiyong Zhang, James Ober, Daniel Kliebenstein
University of California-Davis
Glucosinolates are sulfur-rich plant secondary metabolites present in all cruciferous plants that require hydrolysis for
activation. Their breakdown products have a wide range of biological activities in plant-herbivore and plant-pathogen
interactions and anti-carcinogenic properties that are determined by the resulting chemical structure. In Arabidopsis
and Brassica, hydrolysis by the enzyme, myrosinase, produces the bioactive nitriles, epithionitriles or isothiocyanates
depending upon the plants genotype and the glucosinolates structure. Two QTL, ESP and ESM1, function to determine
formation of epithionitriles and nitriles. We have cloned both QTL and they have opposing functions. ESP directs nitrile
formation while ESM1 inhibits nitrile formation. Both proteins have been shown to interact with myrosinase in other
species suggesting that the myrosinase protein complex functions to control the structural outcome of glucosinolate
hydrolysis. We have extended this work to show that ESP and ESM1 control the in planta formation of Indole-3-
acetonitrile, a potential auxin precursor. In addition to the biochemical function, we are studying the downstream impact on
Arabidopsis/Insect interactions. The glucosinolate hydrolysis profile change towards isothiocyanate formation controlled
by ESM1 is associated with resistance to Trichoplusia ni. We have recently identified associated variation within Brassica
vegetables that could allow for potential improvement of human nutrition. Work on associating this phenotypic variation
with genetic variation within ESP and ESM1 will be presented. We have recently identified associated variation within
vegetables that could allow for potential improvement of human nutrition.
The myrosinase protein complex is comprised of a large number of proteins. A number of these proteins are ESP
or ESM1 homologues. Interestingly, the ESP and ESM1 homologues are interspersed in the same two gene clusters on
Chromosome 1, and another is on Chromosome 3. Thus, suggesting that they are undergoing parallel evolution. These
homologues show high similarity with ESM1 or ESP in both gene structure and protein features. We are currently using
T-DNA Knockouts, 35S-overexpression and biochemistry to test if these homologues also control structural specificity
during glucosinolate hydrolysis. Preliminary genomic analysis will be presented.
Department of Plant Sciences, University of California, Davis, CA 95616.
To whom correspondence should be addressed: kliebenstein@ucdavis.edu
348 Isolation for mutants of higher accumulated elements and pigments from rice FOX lines
Youichi Kondou 1 , Mika Kawashima 1 , Takanari Ichikawa 1 , Akie Ishikawa 1 , Hirohiko Hirochika 2 , Minami Matsui 1
1
PSC, RIKEN, 2 National Institute of Agrobiological Sciences
FOX hunting system is novel gain-of-function technique. In this system, random over-expression of a normalized
plant's full-length cDNA library cause dominant gain-of-function mutations and it is expected that plant acquire useful
phenotype. We are establishing rice FOX lines using 13,000 non-redundant rice full-length cDNAs to introduce them
into Arabidopsis plants. At present, we are screening these lines with various trait for exploration of useful rice genes.
In this study, we will introduce screening strategy for isolation of mutants of higher accumulated elements and pigments
(Elements and Pigments) in rosette leaves as examples of useful phenotype. We already isolated some mutants by prescreening
in T1 generation from about 3,000 lines.
This research is supported by the Special coordination funds for Promoting Science and Technology entitled Rapid
identification of useful traits using rice full-length cDNAs.