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. 2015 Dec;8(1):36.
doi: 10.1186/s12284-014-0036-z. Epub 2015 Jan 20.

Forward screening for seedling tolerance to Fe toxicity reveals a polymorphic mutation in ferric chelate reductase in rice

Siriphat Ruengphayak  1 , Vinitchan Ruanjaichon, Chatree Saensuk, Supaporn Phromphan, Somvong Tragoonrung, Ratchanee Kongkachuichai, Apichart Vanavichit
Affiliations

Forward screening for seedling tolerance to Fe toxicity reveals a polymorphic mutation in ferric chelate reductase in rice

Siriphat Ruengphayak et al. Rice (N Y). 2015 Dec.

Abstract

Background: Rice contains the lowest grain Fe content among cereals. One biological limiting factor is the tolerance of rice to Fe toxicity. Reverse and forward genetic screenings were used to identify tolerance to Fe toxicity in 4,500 M4 lines irradiated by fast neutrons (FN).

Findings: Fe-tolerant mutants were successfully isolated. In the forward screen, we selected five highly tolerant and four highly intolerant mutants based on the response of seedlings to 300 ppm Fe. Reverse screening based on the polymorphic coding sequence of seven Fe homeostatic genes detected by denaturing high performance liquid chromatography (dHPLC) revealed MuFRO1, a mutant for OsFRO1 (LOC_Os04g36720). The MuFRO1 mutant tolerated Fe toxicity in the vegetative stage and had 21-30% more grain Fe content than its wild type. All five highly Fe-tolerant mutants have the same haplotype as the MuFRO1, confirming the important role of OsFRO1 in Fe homeostasis in rice.

Conclusions: FN radiation generated extreme Fe-tolerant mutants capable of tolerating different levels of Fe toxicity in the lowland rice environment. Mutants from both reverse and forward screens suggested a role for OsFRO1 in seedling tolerance to Fe toxicity. The MuFRO1 mutant could facilitate rice production in the high-Fe soil found in Southeast Asia.

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Figures

Figure 1
Figure 1
Schematic view of mutant discovery for rice mutant tolerance to Fe toxicity by reverse and forward genetic screens of a large FN-treated population.
Figure 2
Figure 2
Distribution of responses to Fe toxicity of 4,500 M 4 lines in Fe-toxic (pH 3.0, FeEDTA 300 ppm) nutrient solution at the five-leaf seedling stage. The outcome of A) the 1st round of screening and B) the 2nd round of screening on 152 M4 mutants consisting of 95 tolerant and 57 intolerant M4 lines selected from the first round of mutants.
Figure 3
Figure 3
Average leaf bronzing index (LBI) scored after exposure to Fe toxicity on seven selected mutants compared with the JHN wild type. (DAT: Day after treatment).
Figure 4
Figure 4
The dHPLC chromatograms of the OsFRO1 amplicons. A) The heteroduplex chromatogram was identified on 1D-DNA pooling No. P0024C12 (ratio1:24) compared to JHN-WT. B) The individual mutant line, a member of DNA pool No. P0024C12 that contained the mutant genotype, was identified in a 1:1 admixture with JHN WT.
Figure 5
Figure 5
Genotyping of JHN and MuFRO1 using bi-directional SNP primers for a single amino acid polymorphism (SAP) in Exons 4 and 5. Expected amplicon size of the SAP in Exon 4: SAPEx.4 F/R = 435 bp, SAP_A/SAPEx. 4_R = 268 bp and SAPEx.4 F/SAP-G = 204 bp. Expected amplicon size of the SAP in Exon 5: SAPEx.5 F/R = 402 bp, SAPEx.5 F/SAP-C = 341 bp and SAP_G/SAPEx. 5_R = 97 bp.
Figure 6
Figure 6
Rice plant treated with toxic nutrient solutions (300 ppm) for three weeks: A) wild type and B) MuFRO1 and under control (4 ppm) conditions: C) wild type and D) MuFRO1.
See this image and copyright information in PMC

References

    1. Ando T. Nature of oxidizing power of rice roots. Plant Soil. 1983;72:57–71. doi: 10.1007/BF02185094. - DOI
    1. Arbeit W. Developing a standardized procedure to screen lowland rice (Oryza sativa) seedlings for tolerance to iron toxicity. Germany: MSc Thesis, Rheinischem Friedrich-Wilhelms University; 2003. p. 46.
    1. Bashir K, Hanada K, Shimizu M, Seki M, Nakanishi H, Nishizawa NK. Transcriptomic analysis of rice in response to iron deficiency and excess. Rice. 2014;7:18. doi: 10.1186/s12284-014-0018-1. - DOI - PMC - PubMed
    1. Bashir K, Ishimaru Y, Nishizawa NK. Iron uptake and loading into rice grains. Rice. 2010;3:122–130. doi: 10.1007/s12284-010-9042-y. - DOI
    1. Becker M, Asch F. Iron toxicity in rice—conditions and management concepts. J Plant Nutr Soil Sci. 2005;168:558–573. doi: 10.1002/jpln.200520504. - DOI