Abstract 
         
         The tu8  mutant of Arabidopsis thaliana  (L.) Heynh. was previously described as deficient in pathogen-induced auxin and glucosinolate
            (GSL) accumulation, as well as in heat-induced accumulation of cytosolic Hsp90, the
            latter feature was accom„panied by reduced thermotolerance at higher temperatures.
            The mutated gene was shown to be a novel allele ofTERMINAL FLOWER2,  encoding the only Arabidopsis  homolog for heterochromatin protein 1 ([Kim et al., 2004 tu8. tu8  had less sinapine and sinapoyl esters compared to the wild type. In addition, the
            induction of sinapine by heat shock in Columbia was not found in tu8.  Anthocyanins were also induced by heat stress in wild type plants, whereas tu8  showed only slight induction of these compounds and only at higher temperatures.
            GSLs were induced at higher temperatures in the wild type, but induction was absent
            in tu8.  Transcript levels known to be involved in IAA/glucosinolate synthesis and metabolism
            (nitrilase and myrosinase) were examined and both showed developmental regulation,
            while only nitrilase mRNA levels differed between wild type and mutant seedlings.
            Treatment of Columbia and tu8  with jasmonic acid (JA), a known inducer of glucosinolates, showed differences between
            wild type and tu8  with respect to induction of individual GSLs and anthocyanins. However, the transcript
            level of the TU8/TFL2  gene after heat shock and jasmonate treatment did not change. Loss of function or
            altered function in the heterochromatin protein most likely lead to the pleiotropic
            phenotype observed for the tu8  mutant.
         
         
         
            
Key words 
         
         
            
               Arabidopsis 
               - auxin - glucosinolate - anthocyanin - heat shock - heterochromatin protein 1 homolog
               - jasmonic acid - phenylpropanoid pathway - sinapine derivatives.
          
       
    
   
      
         References 
         
         
            Drosophila  PEV-modifier Su(var) 3-9 encode centromere-associated proteins which complex with
               the heterochromatin component M31. 
               EMBO Journal. 
               (1999); 
               18 
               1923-1938 
               (Brassica campestris)  and oilseed rape (Brassica napus) : Glucosinolate and IAA biosynthetic enzymes. 
               Planta. 
               (1995); 
               196 
               239-244 
               Plasmodiophora brassicae,  the causal agent of the clubroot disease, does not affect expression of NIT1/2-related
               nitrilases in roots of Chinese cabbage. 
               Journal of Plant Physiology. 
               (1995); 
               147 
               341-345 
               Arabidopsis thaliana. 
               . 
               Phytochemistry. 
               (2002); 
               59 
               343-346 
               Arabidopsis thaliana. 
               . 
               Phytochemistry. 
               (2003); 
               62 
               471-481 
               Arabidopsis tu8  mutant. Plant Biology 2001, Providence, RI, USA, http://216.133.76.127/pb2001/public/P33/0217.html . (2001) Alternaria brassicae  (Berk) Sacc. 
               Annals of Applied Biology. 
               (1991); 
               118 
               469-477 
               LIKE HETEROCHROMATIN PROTEIN 1  affect flowering time and plant architechture in Arabidopsis. 
               . 
               Development. 
               (2001); 
               128 
               4847-4858 
               Arabidopsis thaliana  mutant deficient in the expression of O-methyltransferase impacts lignins and sinapoyl
               esters. 
               Plant Molecular Biology. 
               (2003); 
               51 
               973-989 
               Arabidopsis thaliana  plants expressing one nitrilase isoform in sense or antisense direction. 
               Journal of Plant Physiology. 
               (1998); 
               153 
               446-456 
               Arabidopsis thaliana.  The glucosinolates. 
               Plant Physiolology. 
               (1991); 
               97 
               217-226 
               Arabidopsis  ref2  mutant is defective in the gene encoding CYP83A1 and shows both phenylpropanoid and
               glucosinolate phenotypes. 
               Plant Cell. 
               (2003); 
               15 
               179-194 
               Arabidopsis  requires correction for nonenzymatic conversion of indolic nitriles. 
               Plant Physiology. 
               (1996); 
               111 
               781-788 
               Arabidopsis  TU8 glucosinolate mutation, an allele of TERMINAL FLOWER2. 
               . 
               Plant Molecular Biolology. 
               (2004); 
               54 
               671-682 
               Arabidopsis TERMINAL FLOWER2  gene encodes a heterochromatin protein 1 homolog and repesses both FLOWERING LOCUS T  to regulate flowering time and several floral homeotic genes. 
               Plant and Cell Physiology. 
               (2003); 
               44 
               555-564 
               Arabidopsis thaliana  (L.) Heynh: Are they identical?. 
               Plant and Cell Physiology. 
               (1992); 
               33 
               1115-1125 
               Arabidopsis thaliana  L. glucosinolate mutants and the development of the clubroot disease. 
               Planta. 
               (1999); 
               208 
               409-419 
               Arabidopsis thaliana  is thermosensitive and defective in cytosolic Hsp90 expression after heat stress. 
               Plant Physiology. 
               (2000); 
               123 
               949-958 
               Arabidopsis  by defense signaling pathways. 
               Plant Physiology. 
               (2003); 
               131 
               298-308 
               Drosophila. 
               . 
               Proceedings of the National Academy of Sciences of the USA. 
               (1991); 
               88 
               263-267 
               bus,  a bushy Arabidopsis  CYP79F1 knockout mutant with abolished synthesis of short-chain aliphatic glucosinolates. 
               Plant Cell. 
               (2001); 
               13 
               351-367 
               Brassica  vegetables. 
               Chemical-Biological Interaction. 
               (1997); 
               103 
               79-129 
               Glucosinolates.  Singh, B. J., ed. Plant Amino Acids: Biochemistry and Biotechnology. New York; Marcel
               Dekker Inc. (1999): 523-562 A. thaliana  tu8  mutant. Deutsche Botanikertagung, Freiburg, Germany. (2002) Arabidopsis : involvement of cytochrome P450s CYP79B2 and CYP79B3. 
               Genes and Development. 
               (2002); 
               16 
               3100-3112 
                
         
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         Editor: E. Pichersky