A Na(+)-independent organic anion transport protein was recently cloned from rat liver using a Xenopus laevis oocyte expression system [E. Jacquemin, B. Hagenbuch, B. Stieger, A.W. Wolkoff, and P.J. Meier, Proc. Natl. Acad. Sci. USA 91: 133-137, 1994]. Although expression of this protein is sufficient for cells to transport the organic anion bromosulfophthalein, little is known about its cell biology or biochemical characteristics. Northern blot analysis performed under high-stringency conditions revealed hybridization with RNA only from liver and kidney; transcripts appeared the same in these two organs. Within kidney, hybridization was greatest when RNA extracted from the outer medulla was used. Immunoblot analysis revealed that in liver, the transporter was enriched in 0.1 M Na2CO3-extracted membranes and sinusoidal plasma membrane preparations, consistent with its being an integral membrane protein. This 80-kDa protein migrated as a 65-kDa protein after treatment with N-glycanase. Immunomorphological examination of liver revealed basolateral plasma membrane localization. In 0.1 M Na2CO3-extracted membranes of kidney, the transporter migrated as an 83-kDa protein on nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). On reduction, it resolved into peptides of 33 and 37 kDa. SDS-PAGE migration of the liver protein was unaffected by reduction. Immunomorphological examination of kidney revealed apical plasma membrane localization in the S3 segment of the proximal tubule of the outer medulla. Differential processing and trafficking of this transporter in liver and kidney may have important functional and regulatory consequences.

Non-target-site resistance (NTSR) to herbicides is a worldwide concern for weed control. However, as the dominant NTSR mechanism in weeds, metabolic resistance is not yet well-characterized at the genetic level. For this study, we have identified a shortawn foxtail (Alopecurus aequalis Sobol.) population displaying both TSR and NTSR to mesosulfuron-methyl and fenoxaprop-P-ethyl, yet the molecular basis for this NTSR remains unclear. To investigate the mechanisms of metabolic resistance, an RNA-Seq transcriptome analysis was used to find candidate genes that may confer metabolic resistance to the herbicide mesosulfuron-methyl in this plant population. The RNA-Seq libraries generated 831,846,736 clean reads. The de novo transcriptome assembly yielded 95,479 unigenes (averaging 944 bp in length) that were assigned putative annotations. Among these, a total of 29,889 unigenes were assigned to 67 GO terms that contained three main categories, and 14,246 unigenes assigned to 32 predicted KEGG metabolic pathways. Global gene expression was measured using the reads generated from the untreated control (CK), water-only control (WCK), and mesosulfuron-methyl treatment (T) of R and susceptible (S). Contigs that showed expression differences between mesosulfuron-methyl-treated R and S biotypes, and between mesosulfuron-methyl-treated, water-treated and untreated R plants were selected for further quantitative real-time PCR (qRT-PCR) validation analyses. Seventeen contigs were consistently highly expressed in the resistant A. aequalis plants, including four cytochrome P450 monooxygenase (CytP450) genes, two glutathione S-transferase (GST) genes, two glucosyltransferase (GT) genes, two ATP-binding cassette (ABC) transporter genes, and seven additional contigs with functional annotations related to oxidation, hydrolysis, and plant stress physiology. These 17 contigs could serve as major candidate genes for contributing to metabolic mesosulfuron-methyl resistance; hence they deserve further functional study. This is the first large-scale transcriptome-sequencing study to identify NTSR genes in A. aequalis that uses the Illumina platform. This work demonstrates that NTSR is likely driven by the differences in the expression patterns of a set of genes. The assembled transcriptome data presented here provide a valuable resource for A. aequalis biology, and should facilitate the study of herbicide resistance at the molecular level in this and other weed species.

Recently we expression cloned a rat liver organic anion transport protein in

Phosphorus (P) is an essential element for all organisms. Because P fertilizers are a non-renewable resource and high fixation in soils, sustainable agriculture requires researchers to improve crop P acquisition efficiency. Here, we report a strong association signal at a locus of CPU1 (component of phosphorus uptake 1), from a genome-wide association study of P acquisition efficiency in a soybean core collection grown in the field. A SEC12-like gene, GmPHF1, is identified as the causal gene for CPU1. GmPHF1 facilitates the ER (endoplasmic reticulum) exit of the phosphate transporter, GmPT4, to the plasma membrane of root epidermal cells. A common SNP in an upstream open reading frame (uORF) of GmPHF1, which alters the abundance of GmPHF1 in a tissue-specific manner, contributes to P acquisition diversity in soybean. A natural genetic variation conditions diversity in soybean P acquisition, which can be used to develop P-efficient soybean genotypes.

BACKGROUND Asia minor bluegrass (Polypogon fugax Nees ex Steud.) is an invasive grass species severely infesting wheat and canola fields in China. In May 2017, a suspected resistant P. fugax population AHHY that survived fenoxaprop‐P‐ethyl applied at its field‐recommended rate was collected from a wheat field in Huaiyuan County, Anhui Province, China. This study aimed to determine the resistance profile of AHHY to acetyl‐CoA carboxylase (ACCase) inhibitors and to investigate its mechanisms of resistance to fenoxaprop. RESULTS Single‐dose testing indicated that the AHHY population had evolved resistance to fenoxaprop. The partial carboxyltransferase domain of ACCase in P. fugax was amplified and compared. Four loci encoding plastidic ACCase were isolated from both the resistant and sensitive individuals. Combining gene sequencing with the derived cleaved amplified polymorphic sequence assay, we found that 100% of the plants of AHHY carried Trp‐1999‐Ser mutation in their ACCase1,1–2 allele. Whole‐plant dose–response bioassay indicated that AHHY was highly resistant to fenoxaprop and pinoxaden (resistance index (RI) ≥ 10) with low resistance to clodinafop‐propargyl, sethoxydim, and clethodim (2 ≤ RI < 5). Pre‐treatment with piperonyl butoxide largely reduced (55%) the weed's resistance to fenoxaprop. Both basal and fenoxaprop‐induced glutathione S‐transferases activities toward 1‐chloro‐2, 4‐dinitrobenzene were significantly higher in resistant plants than in susceptible plants. CONCLUSION This study revealed that P. fugax had multiple alleles encoding plastidic ACCase, and reported for the first time the occurrence of Trp‐1999‐Ser mutation and non‐target‐site resistance in this species. Fenoxaprop resistance in AHHY plants was conferred by target‐site mutation and P450s‐involved enhanced metabolism. © 2019 Society of Chemical Industry