scholarly journals Peer Review #1 of "The pht4;1-3 mutant line contains a loss of function allele in the Fatty Acid Desaturase 7 gene caused by a remnant inactivated selection marker—a cautionary tale (v0.1)"

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4134
Author(s):  
Anders K. Nilsson ◽  
Mats X. Andersson

A striking and unexpected biochemical phenotype was found in an insertion mutant line in the model plant Arabidopsis thaliana. One of two investigated insertion mutant lines in the gene encoding the phosphate transporter PHT4;1 demonstrated a prominent loss of trienoic fatty acids, whereas the other insertion line was indistinguishable from wild type in this aspect. We demonstrate that the loss of trienoic fatty acids was due to a remnant inactive negative selection marker gene in this particular transposon tagged line, pht4;1-3. This constitutes a cautionary tale that warns of the importance to confirm the loss of this type of selection markers and the importance of verifying the relationship between a phenotype and genotype by more than one independent mutant line or alternatively genetic complementation.


2006 ◽  
Vol 131 (2) ◽  
pp. 284-289 ◽  
Author(s):  
Mauricio A. Cañoles ◽  
Randolph M. Beaudry ◽  
Chuanyou Li ◽  
Gregg Howe

Six-carbon aldehydes and alcohols formed by tomato (Lycopersicon esculentum Mill.) leaf and fruit tissue following disruption are believed to be derived from the degradation of lipids and free fatty acids. Collectively, these C-6 volatiles comprise some of the most important aroma impact compounds. If fatty acids are the primary source of tomato volatiles, then an alteration in the fatty acid composition such as that caused by a mutation in the chloroplastic omega-3-fatty acid desaturase (ω-3 FAD), referred to as LeFAD7, found in the mutant line of `Castlemart' termed Lefad7, would be reflected in the volatile profile of disrupted leaf and fruit tissue. Leaves and fruit of the Lefad7 mutant had ≈10% to 15% of the linolenic acid (18:3) levels and about 1.5- to 3-fold higher linoleic acid (18:2) levels found in the parent line. Production of unsaturated C-6 aldehydes Z-3-hexenal, Z-3-hexenol, and E-2-hexenal and the alcohol Z-3-hexenol derived from 18:3 was markedly reduced in disrupted leaf and fruit tissue of the Lefad7 mutant line. Conversely, the production of the saturated C-6 aldehyde hexanal and its alcohol, hexanol, were markedly higher in the mutant line. The shift in the volatile profile brought about by the loss of chloroplastic FAD activity in the Lefad7 line was detected by sensory panels at high significance levels (P < 0.0005) and detrimentally affected fruit sensory quality. The ratios and amounts of C-6 saturated and unsaturated aldehydes and alcohols produced by tomato were dependent on substrate levels, suggesting that practices that alter the content of linoleic and linolenic acids or change their ratios can influence tomato flavor.


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