AUTHOR=Yang Jiajia , Jiang Minghao , Jia Siwei , Liao Min , Cao Haiqun , Zhao Ning 

TITLE=Expression Pattern of Entire Cytochrome P450 Genes and Response of Defenses in a Metabolic-Herbicide-Resistant Biotype of Polypogon fugax

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.868807

DOI=10.3389/fpls.2022.868807

ISSN=1664-462X

ABSTRACT=<p>Enhanced herbicide metabolism mediated by cytochrome P450s has been proposed as one of the major mechanisms of resistance to fenoxaprop-<italic>P</italic>-ethyl in a metabolic-herbicide-resistant biotype of Asia minor bluegrass (<italic>Polypogon fugax</italic> Nees ex Steud.). Upon pre-treatment with the P450 inhibitor piperonyl butoxide, a remarkable reduction in metabolic rates of the phytotoxic fenoxaprop-<italic>P</italic> has been observed in the resistant plants, implying that constitutive and/or fenoxaprop-<italic>P</italic>-ethyl-induced up-regulation of specific P450 isoforms are involved in the fenoxaprop-<italic>P</italic>-ethyl resistance. However, which P450 gene(s) were responsible for the metabolic resistance is still unknown. In this present study, based on the abundant gene resources of <italic>P. fugax</italic> established previously, a total of 48 putative P450 genes were isolated from the metabolic-herbicide-resistant plants and used for gene expression analysis. The most suitable reference genes for accurate normalization of real-time quantitative PCR data were first identified in <italic>P. fugax</italic> and recognized as actin (<italic>ACT</italic>), 18S rRNA (<italic>18S</italic>), and ribulose-1,5-bisphosphate carboxylase oxygenase (<italic>RUBP</italic>) under fenoxaprop-<italic>P</italic>-ethyl stress, glyceraldehyde-3-phosphate dehydrogenase (<italic>GAPDH</italic>) and elongation factor 1α (<italic>EF1α</italic>) under mesosulfuron-methyl stress, and <italic>ACT</italic>, <italic>EF1α</italic>, eukaryotic initiation factor 4a (<italic>EIF4A</italic>), and 25S rRNA (<italic>25S</italic>) at different growth stages. Expression analysis of the putative P450 genes revealed that six genes, respectively, annotated as <italic>CYP709B1</italic>, <italic>CYP71A1-4</italic>, <italic>CYP711A1</italic>, <italic>CYP78A9</italic>, <italic>P450-11</italic>, and <italic>P450-39</italic> were up-regulated more than 10-fold in the resistant plants by fenoxaprop-<italic>P</italic>-ethyl treatment, and all of them exhibited constitutively and/or herbicide-induced higher transcript levels in the fenoxaprop-<italic>P</italic>-ethyl-resistant than in the susceptible plants. Three genes, respectively, annotated as <italic>CYPRO4</italic>, <italic>CYP313A4</italic>, and <italic>CYP51H11</italic> constantly up-regulated in the resistant than in the susceptible plants after fenoxaprop-<italic>P</italic>-ethyl treatment. Up-regulated expressions of these specific P450 genes were consistent with the higher P450 contents determined in the resistant plants. These results will help to elucidate the mechanisms for P450-mediated metabolic-herbicide resistance in <italic>P. fugax</italic> as well as other grass weed species.</p>