Os04g0459000

The rice Os04g0459000 was reported as OsABCB14 in 2014 by researchers from China.

Annotated Information

Figure 1. Identification of osabcb14 mutants and complemented lines..

Gene Symbol

• Os04g0459000 <=> OsABCB14,ABCB14

Function

• A knock-down of OsABCB14 confers decreased auxin concentrations and polar auxin transport rates, conferring insensitivity to 2,4-D and IAA.
• OsABCB14 displays enhanced specific auxin influx activity in yeast and protoplasts prepared from rice knock-down alleles.
• OsABCB14 is an auxin influx transporter involved in iron homeostasis. The functional characterization of OsABCB14 provides insights in monocot auxin transport and its relationship to Fe nutrition.

Phenotypic analysis

• The researchers first investigated the phenotypes of shoots and primary roots (PRs) of NIP, osabcb14 mutants and osabcb14C. The shoot and PR lengths in NIP for 7d seedling were only slightly shorter than those of osabcb14-1 and osabcb14-2 under normal conditions (CK) (Figure 1e), while significantly shorter than those of osabcb14-1 and osabcb14-2 under 0.01μM 2,4-D treatment (Figure 1f). Similar results were obtained when grown in the nutritional solution containing 10μM IAA (Figure 1g).
• However, there was no difference between NIP and osabcb14 mutants under treatment of 0.001~1μM NAA. We further performed a dose-response assay to confirm the effect of 2,4-D, IAA and NAA in more details.
• High concentration of all the three auxins inhibited the shoot and PR growth, but more prominent in NIP than osabcb14 mutants under 2,4-D treatment at a concentration of >10 -8 mol l -1 (Figure 1h,i) and IAA treatment at a concentration of >10 -7 mol l -1 (Figure 1j,k), while no significant difference under NAA treatment.
• All these phenotypes in osabcb14 mutants could be reverted by transgenic lines osabcb14C (Figure 1e-k). These results confirmed that osabcb14 mutants are insensitive to 2,4-D and IAA, but not responsive to NAA.
• These observations were similar to the previous studies on AUX1 (Delbarre et al., 1996; Yang et al., 2006), suggesting that OsABCB14 is required for auxin transport in either shoot or root.

Expression

• The expression pattern of OsABCB14 was analyzed in different organs and growth stages using qRT-PCR. The results showed that OsABCB14 expression is constitutive in various organs.
• At all growth stages observed, OsABCB14 was ubiquitously expressed in all plant organs, including the root, stem, leaf, node, root-stem transition region, filling seed, panicle and flower (Figure 2a).
• Spatial expression analysis showed that the expression of OsABCB14 was higher in root tips than in the basal root zones (Figure 2b).
• GUS staining revealed that OsABCB14 is expressed in the root tip and stele of the PR and leaves. Cross section of leaf sheath showed that OsABCB14 is expressed in the vascular (Figure 2c-f). OsABCB14 is also strongly expressed in node, internode, root-stem transition region and flowers (Figure 2g-j).

Subcellular localization

• OsABCB14 was cloned into pH7FWG2 and that like fused with the enhanced green fluorescent protein (EGFP). Transient expression of OsABCB14 in the epidermis cells of N. benthamiana leaves and onion epidermis indicating that OsABCB14 was localized at the plasma membrane

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Labs working on this gene

• State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, China;
• Department of Biology - Plant Biology, University of Fribourg, Rue Albert-Gockel 3, CH-1700 Fribourg, Switzerland
• State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
• State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, China
• State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.