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

Abstract

BackgroundRice 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).FindingsFe-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.ConclusionsFN 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-014-0036-z) contains supplementary material, which is available to authorized users.

QTL mapping and candidate gene analysis of ferrous iron and zinc toxicity tolerance at seedling stage in rice by genome-wide association study

“…Higher Fe and Zn concentrations in the grains are desirable for human health. Ruengphayak found that the MuFRO1 mutant which tolerated Fe toxicity in the vegetative stage had 21–30% more grain Fe content than its wild type [ 47 ]. Therefore, breeding resistant rice varieties that tolerate high Fe and Zn concentrations with high content in the grains is an effective way to avoid soil pollution effects on agriculture [ 48 ].…”

Association Mapping of Ferrous, Zinc, and Aluminum Tolerance at the Seedling Stage in Indica Rice using MAGIC Populations

“…A number of studies have reported QTL for tolerance to a variety of metal. With regards to Fe toxicity in rice, a total of 197 QTL have been reported (Wu et al, 1997 , 1998 , 2014 ; Wan J. L. et al, 2003a ; Wan J. M. et al, 2003b ; Wan et al, 2005 ; Shimizu et al, 2005 ; Ouyang et al, 2007 ; Dufey et al, 2009 , 2012 , 2015 ; Fukuda et al, 2012 ; Zhang et al, 2013 ; Zhao et al, 2013 ; Matthus et al, 2015 ; Ruengphayak et al, 2015 ; Liu et al, 2016 ). A total of four chromosomal regions (CR), including CR1 on chromosome 1 between markers RM246 and RM443; CR2 on chromosome 2 between markers RM526 and R758; CR3 on chromosome 3 between markers C515 and C25; and CR4 on chromosome 7 between markers R1245 and RM429, have been found to be involved in the resistance of rice to Fe toxicity (Dufey et al, 2014 ).…”

Comparative in Silico Analysis of Ferric Reduction Oxidase (FRO) Genes Expression Patterns in Response to Abiotic Stresses, Metal and Hormone Applications

“…The functional prediction and database searching also suggested that OsFRO1 involvement in iron homeostasis [ 33 ] and the expression have been reported in leaves of Zn 2− , Mn 2− - and Cu 2− -deficient plants [ 48 ]. The expression of OsFRO1 gene was significantly correlated with Fe and/or Zn concentrations in seeds [ 66 ].…”

“…In rice only two ‘FRO-like’ genes ( OsFRO1 and OsFRO7 ) were identified, having unique functional characteristics in Fe uptake and abiotic stresses [ 16 , 32 ]. The expression of OsFRO1 was noticed in Zn 2− -, Mn 2− - and Cu 2− -deficient rice leaves and later their role in iron homeostasis and bulky biomass under Fe toxic condition was confirmed by [ 33 ], The rice OsFRO1 mutant showed more Fe content in grain when grown in iron-toxic soil [ 33 ]. Likewise, the knockdown of LeFRO1 transgene showed its effect on Fe partition in Nicotiana benthamiana [ 26 ].…”