Disease relevance of PDS3

• In contrast, a strain of E. coli carrying geranylgeranyl diphosphate synthase, phytoene desaturase and the bacterial carotene desaturase CrtI, which mediates lycopene formation from phytoene, does not require light, nor is a poly-cis-lycopene species formed [1].
• We have expressed in Escerichia coli the enzymes geranylgeranyl diphosphate synthase and phytoene synthase, from the soil bacterium Erwinia stewartii, and the two carotene desaturases phytoene desaturase and carotene zeta-carotene desaturase from Arabidopsis thaliana [1].

High impact information on PDS3

• RNA silencing of ribulose-1,5-bisphosphate carboxylase/oxygenase and phytoene desaturase was not associated with the spreading of RNA targeting or DNA methylation, indicating that these endogenous RNAs are not templates for SDE1/SGS2 [2].
• Surprisingly, neither mutation maps to the locus encoding the phytoene desaturase enzyme, indicating that the products of at least three loci are required for phytoene desaturation in higher plants [3].
• Because phytoene desaturase catalyzes an oxidation reaction, it has been suggested that components of an electron transport chain may be involved in this reaction [3].
• The CaMV replicon carrying the pds gene fragment produced unusual infection characteristics, with plants showing early symptoms and then recovering [4].
• An intron and flanking sequences from the RNA leader of the Arabidopsis phytoene desaturase (pds) gene, when inserted into the 35S enhancer in forward orientation was very efficiently spliced during infection [4].

Biological context of PDS3

• Assessment of penetrance and expressivity of RNAi-mediated silencing of the Arabidopsis phytoene desaturase gene [5].
• An inverse correlation between PDS mRNA level and RNAi phenotype was seen [5].
• We have successfully silenced the phytoene desaturase (PDS) gene in the diploid wild species Solanum bulbocastanum and S. okadae, in the cultivated tetraploid S. tuberosum and in the distant hexaploid relative S. nigrum (commonly known as deadly nightshade) [6].
• PSY needs to be supplemented and the need for the CrtI transgene in Golden Rice is presumably due to insufficient activity of the phytoene desaturase and/or zeta-carotene desaturase enzyme in endosperm [7].
• With light, there is an up-regulation of PSY expression, the first gene within the carotenoid biosynthetic pathway, while PDS and GGPS expression levels remain constant [8].

Anatomical context of PDS3

• As the phytoene desaturase and zeta-carotene desaturase used originate from a system not capable of developing chromoplasts, this indicates that the poly-cis pathway of carotene desaturation may have a wider occurrence than initially believed [1].

Associations of PDS3 with chemical compounds

• Previous analyses of phytoene-accumulating tissue suggested that there may be feedback regulation of PDS gene transcription, with higher expression in white tissue [9].
• The two-step desaturation of phytoene to zeta-carotene, carried out by the enzyme phytoene desaturase (PDS), is one of the earliest steps in the pathway and has been studied in several systems [9].
• Seedlings harbouring Thr304 pds had a maximum resistance to sensitivity (R/S) ratio of 57 and 14 times higher than that of the wild-type for treatments with norflurazon and fluridone, respectively [10].
• Thr, the three natural mutations [Cys, serine (Ser), histidine (His)] and the wild-type PDS protein were tested in vitro against seven inhibitors of PDS representing several classes of herbicides [10].
• We substituted the arginine 304 present in the wild-type H. verticillata phytoene desaturase (PDS) with all 19 other natural amino acids and tested PDS against fluridone [10].

Other interactions of PDS3

• To evaluate the efficiency of this system, RNA corresponding to the phytoene desaturase gene of Arabidopsis thaliana was used as a reporter gene in transgenic plants and a comparative study was performed using either the CaMV35S constitutive promoter or the HSP18.2 inducible promoter [11].

References