A. thaliana mutants

Modulation of the quantity and/or quality of poly(3HAMCL) synthesized in peroxisomes was also achieved by modifying the endogenous fatty acid biosynthetic pathway [58]. For example, expression of the peroxisomal PHA synthase in an A. thaliana mutant deficient in the synthesis of triunsaturated fatty acids [59] resulted in the synthesis of a PHA having an almost complete absence of triunsaturated 3-hydroxyacid monomers [58]. In a different strategy, expression of a fatty acyl-ACP thio esterase in the plastid was combined with the expression of a peroxisomal PHA synthase [58]. Fatty acyl-ACP thioesterases are... 

The Kacser—Burns approach has been used in the analysis of starch synthesis by mutants of Arabidopsis thaliana that studied leaf ADP-Glc PPase, and the significance of 3-PGA regulation in vivo A. thaliana mutant strains containing only 7% of the wild-type activity of ADP-Glc PPase and a hybrid of mutant and wild type with 50% activity, had 10% and 61% of the wild type s starch synthetic rate, respectively, at high light intensity. This is a fairly good correlation between the activity of the ADP-Glc PPase and the rate of synthesis of starch. The flux control coefficient was determined to be 0.64. 

A. thaliana mutants have also provided a means of eloning genes difficult to isolate by other methods. As in other kingdoms, the membrane-bound enzymes of plants have been... 

Genetic Loci of A. thaliana Involved in Flavonoid Biosynthesis for which Genetic Mutants and the Encoded Product Have Been Characterized... 

Yeast does not synthesise cycloartenol or triterpenes, and so approaches to clone plant OSCs by complementation in S. cerevisiae are not feasible because of the lack of appropriate mutants. However, LS-deficient yeast mutants accumulate high levels of 2,3-oxidosqualene, favouring the synthesis of novel cycfisation products generated by heterologous expression of OSCs. The absence of lano-sterol also facilitates analysis of the reaction products. Corey and co-workers isolated a cDNA encoding Arabidopsis thaliana CS by transforming a plant cDNA expression library into such a yeast mutant and screening protein preparations derived from pools of transformants for the ability to synthesise cycloartenol by TLC [39]. 

Point mutations that give altered sterol profiles have been generated in A. thaliana and S. cerevisiae LSs. Matsuda and co-workers used a yeast expression system to select for spontaneous mutations in A. thaliana CS that restored sterol-independent growth to an LS-deficient mutant of yeast [67]. In this way they were able to identify a mutation from isoleucine to valine (at Ile481) that allowed synthesis of the sterols lanosterol and parkeol. Further studies have identified a number of other amino acid residues in A. thaliana CS and... 

The results of a recent study have called this into question. The primary walls of a double mutant of Arabidopsis thaliana in which two xyloglucan xylosyltransferase genes were not expressed were found to contain no detectable xyloglucan (Cavalier et al., 2008). Compared to the wild type, the double mutant was slightly smaller and had abnormal root hairs, yet there was no catastrophic effect on cell-wall integrity as would be predicted from current cell-wall models. A possible explanation is that the pectic polysaccharide network between the... 

STASWICK, P.E., SU, W., HOWELL, S.H., Methyl jasmonate inhibition of root growth and induction of a leaf protein are decreased in an Arabidopsis thaliana mutant, Proc. Natl. Acad. Sci. USA, 1992,89,6837-6840. 

Caspar, C, Huber. S. C., and Somerville, C. 1986. Alterations in growth, photosynthesis and respiration in a starch mutant of Arabidopsis thaliana (L.), Heynh deficient in chloroplast phosphoglucomutase activity. Plant Physiol. 79, 1-7. 

Lin, T. P., Caspar, T., Somerville, C., and Preiss, J. 1988b. Isolation and characterization of a starchless mutant of Arabidopsis thaliana L. Henyh lacking ADPglucose pyrophosphorylase activity. Plant Physiol. 86, 1131-1135. 

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