Identification of apsbAMutation (Valine219to Isoleucine) in Powell Amaranth (Amaranthus powellii) Conferring Resistance to Linuron

Weed Science ◽  
2016 ◽  
Vol 64 (1) ◽  
pp. 6-11 ◽  
Author(s):  
Mélanie Dumont ◽  
Jocelyne Letarte ◽  
François J. Tardif

A Powell amaranth population suspected to be resistant (R) to linuron was discovered in a carrot field in Keswick, Ontario, Canada, in 1999. Dose–response analysis with different herbicides and DNA sequencing of thepsbAgene encoding the D1 protein of photosystem II were done to confirm the resistance and identify its basis. A calculated resistance factor indicated a 12-fold increased resistance when linuron was applied to an R population compared with a susceptible (S) population. Moreover, the R population showed 6.4- and 3.1-fold greater resistance to two other phenylurea herbicides (diuron and monolinuron), 1.8- and 1.4-fold greater resistance to two triazine herbicides (metribuzin and prometryn), and 2.6-fold greater resistance to the triazinone metribuzin. R population was also cross-resistant to bentazon and bromoxynil when compared with S population, with a calculated resistance factor of 1.4 and 2.2, respectively. The partial nucleotide sequence of thepsbAgene of R populations differed at two locations when compared with S populations. The first mutation coded for a Val219Ile substitution in the deduced amino acid sequence of the D1 protein, and the second mutation was silent and encoded for a proline at position 279 in both R and S populations. The Val219Ile substitution in thepsbAgene is most likely the cause of this Powell amaranth population resistance to linuron and other PSII inhibitors. This is the first recorded instance of a Val219Ile substitution in anAmaranthusspecies.

1998 ◽  
Vol 42 (5) ◽  
pp. 1245-1248 ◽  
Author(s):  
François Sanschagrin ◽  
Julien Dufresne ◽  
Roger C. Levesque

ABSTRACT We have determined the nucleotide sequence of the blaSgene encoding the carbapenem-hydrolyzing L-1 β-lactamase fromStenotrophomonas maltophilia GN12873. Analysis of the DNA and deduced amino acid sequences identified a product of 290 amino acids. Comparisons of the L-1 amino acid sequence with those of other zinc β-lactamases showed 88.6% identity with the L-1 enzyme fromS. maltophilia IID1275 and less than 20% identity with other class B metalloenzymes.


Author(s):  
Hoang Thi Thu Yen ◽  
Mai Thi Huyen Trang ◽  
Pham Thi Hang ◽  
Huynh Thi Thu Hue

In this study, we conducted the cloning and sequencing gene encoding FLS from the two green and purple Trung Du tea cultivars. The length of FLS gene is 996 bp, encodes 331 amino acid. Results of FLS gene analysis showed that green and purple Trung Du cultivars has 13 nucleotide variants total as compare with FLS sequence published on Genbank. Nucleotide sequence differences lead to change amino acid sequence of key functional motives in FLS like motif characterizes the 2OG-Fe (II) oxygenase superfamily, the PxxxIRxxx-EQP motif at the N-terminal (18→29) determines the FLS activity, the CPQ/RPxLAL motif) is the binding site of 2-oxoglutarate. How amino acid position changes affect FLS activity need further research. FLS gene isolates are sources for further research to aim elucidating the function of this enzyme.


1990 ◽  
Vol 45 (5) ◽  
pp. 436-440 ◽  
Author(s):  
S. Creuzet ◽  
G. Ajlani ◽  
C. Vernotte ◽  
C. Astier

A new Synechocystis 6714 mutant, loxIIA, resistant to the phenol-type herbicide ioxynil was isolated and characterized. The mutation found in the psbA gene (encoding the D1 photosystem II protein) is at the same codon 266 as for the first ioxynil-resistant mutant IoxIA previously selected [G. Ajlani. I. Meyer, C. Vernotte. and C. Astier, FEBS Lett. 246, 207-210 (1989)]. In IoxIIA, the change of Asn 266 to Asp gives a 3 × resistance, whereas in IoxIA, the change of the same amino acid to Thr gives a 10 × resistance. The effect of these different amino acid substitutions on the ioxynil resistance phenotype has allowed us to construct molecular models and calculate the hydrogen-bonding energies between the hydroxyl group of ioxynil and the respective amino acids at position 266.


1992 ◽  
Vol 38 (3) ◽  
pp. 193-202 ◽  
Author(s):  
Angus Gilchrist ◽  
James A. Fisher ◽  
John Smit

The entire nucleotide sequence of the rsaA gene, encoding the paracrystalline surface (S) layer protein (RsaA) of Caulobacter crescentus CB15A, was determined. The rsaA gene encoded a protein of 1026 amino acids, with a predicted molecular weight of 98 132. Protease cleavage of mature RsaA protein and amino acid sequencing of retrievable peptides yielded two peptides: one aligned with a region approximately two-thirds the way into the predicted amino acid sequence and the second peptide corresponded to the predicted carboxy terminus. Thus, no cleavage processing of the carboxy portion of the RsaA protein occurred during export, and with the exception of the removal of the initial methionine residue, the protein was not processed by cleavage to produce the mature protein. The predicted RsaA amino acid profile was unusual, with small neutral residues predominating. Excepting aspartate, charged amino acids were in relatively low proportion, resulting in an especially acidic protein, with a predicted pI of 3.46. As with most other sequenced S-layer proteins, RsaA contained no cysteine residues. A homology scan of the Swiss Protein Bank 17 produced no close matches to the predicted RsaA sequence. However, RsaA protein shared measurable homology with some exported proteins of other bacteria, including the hemolysins. Of particular interest was a specific region of the RsaA protein that was homologous to the repeat regions of glycine and aspartate residues found in several proteases and hemolysins. These repeats are implicated in the binding of calcium for proper structure and biological activity of these proteins. Those present in the RsaA protein may perform a similar function, since S-layer assembly and surface attachment requires calcium. RsaA protein also shared some homology with 10 other S-layer proteins, with the Campylobacter fetus S-layer protein scoring highest. Key words: Caulobacter crescentus, surface layer, nucleotide sequence, rsaA, calcium.


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