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Annotated Information


This gene also called CYP81A6 gene, encodes a kind of protein named CYP81A6, which belongs to cytochrome P450 monooxygenases family[1]. Cytochrome P450 monooxygenases are NADPH-dependent heme proteins that cast a large and diverse group of isozymers and mediate a wide arrange of oxidative reactions in plants, animals, and microorganisms[1]. In plants, cytochrome P450s mediate biosynthesis of lignins, terpenoid, and alkaloids, sterols,fatty acids, and many secondary compounds that act as plant defense agents. The protein coded by this gene confers resistance to two different kinds of herbicides bentazon and sulfonylurea[1].


Figure 1. Expression of CYP81A6 in various organs of the rice (from reference [1]).
Figure 2. Bentazon-sensitivity of two mutants (from reference [1]).

CYP81A6 gene is transcribed in all organs of rice and is highly expressed in shoots, leaf, leaf sheaths and immature panicles, while it is transcribed at low level in the roots (Figure 1)[1].


BLAST searches revealed that the deduced amino acid sequence of CYP81A6 was highly similar to that of the previously reported chortoluron hydroxylase CYP81B1 from Helianthus tuberrosus(45% identity and 63% similarity)[2] and CYP81B2 from Nicotiana tabacum(44% identity and 59% similarity) [3] and isoflavone hydroxylase CYP81E1 from Glycyrrhiza echinata(42% identity and 63% similarity)[4] and CYP81E9 from Medicago truncatula(42% identity and 63% similarity)[5] nearly over the entire region.


Two bentazon-lethal mutants 8077S and Norin8m are obtained from γ-radiated indica cultivar W6154S[6] and japonica cultivar Norin8[7] respectively. CYP81A6 from 8977S and Norin8m have a single-base deletion of G at the 2058th nucleotide and a single-base deletion of C at the 507th in its coding sequence respectively[1]. Both 8077S and Norin8m plants started to show symptoms to bentazon at 100 mg/l and the lethal concentration was about 300 mg/l(Figure 2). The threshold concentrations of the bentazon sensitivity for the mutant plants were about 60-fold lower than those for their wild-type controls[1].

Labs working on this gene

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  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Pan, G., et al. (2006). Map-based cloning of a novel rice cytochrome P450 gene CYP81A6 that confers resistance to two different classes of herbicides. Plant Mol Biol 61(6): 933-943.
  2. Akashi T, Aoki T, Ayabe S (1998) CYP81E1, a cytochrome P450 cDNA of licorice (Glycyrrhiza echinata L.), encodes isoflavone 2′-hydroxylase. Biochem Biophys Res Commun 251:67–70.
  3. Liu C, Huhman D, Sumner L-W, Dixon RA (2003) Regiospecific hydroxylation of isoflavones by cytochrome P450 81E enzymes from Medicago truncatula. Plant J 36:471–484.
  4. Zhang J, Wu X (1999) Screening and preliminary study on the chemical lethal mutant in rice photoperiod-temperature sensitive male sterile line. Chinese J Rice Sci 13:65–68.
  5. Mori K (1984) Inheritance of susceptible mutant in rice plant to herbicide bentazon. Jpn J Breed 34:421–422.
  6. Cabello-Hurtado F, Batard Y, Salaun JP, Durst F, Pinot F, Werck-Reichart D (1998) Cloning, expression in yeast, and functional characterization of CYP81B1, a plant cytochrome P450 that catalyzes in-chain hydroxylation of fatty acids. J Biol Chem 273:7260–7267.
  7. Yamada T, Kambara Y, Imaishi H, Ohkawa H (2000) Molecular cloning of a novel cytochrome P450 species induced by chemical treatments in tobacco cells. Pestic Biochem Physiol 68:11–25.

Structured Information