Multienvironment Quantitative Trait Loci Mapping and Consistency across Environments of Resistance Mechanisms to Ferrous Iron Toxicity in Rice

Abstract

Lowland rice {Oryza sativa L.) is often affected by iron toxicity, which may iead to yield losses. One important constraint in the study of the inheritance of resistance strategies to this stress is the inconsistency of gene expression across different environments. This study aimed to determine the stability of quantitative trait loci (QTL) across several environments. Quantitative trait loci mapping for traits related to resistance mechanisms had been previously performed using 164 recombinant inbred lines derived from 'Azucena' and 'IR64' screened in hydroponics in a phytotron. In the present study, this population was tested under excessive ferrous iron conditions in three additional environments: in hydroponics in a greenhouse, on washed sand, and in the field. Altogether, 44 putative QTL were identified in the four single QTL analyses for morphological, physiological, and agronomic traits. From these 44 QTL, 20 were found in overlapping regions for the same or related traits in different environments, identifying six genomic regions of great interest for the inheritance of resistance to iron toxicity. Quantitative trait loci stability across environments was also checked by performing a joint QTL analysis, which confirmed the position of nine QTL previously found in the same or adjacent regions by at least one single analysis. Combining both single and joint analyses helps in separating QTL specific to a particular environment from generally expressed ones thus is more suitable for marker-assisted selection.

Genetic Improvement of Iron Toxicity Tolerance in Rice-Progress, Challenges and Prospects in West Africa

“…The effects of these QTLs on chromosome 1 and 3 were confirmed by using CSSL carrying Kasalath introgressions in the genetic background on Nipponbare (Wu et al, 2014). Dufey et al (2012) have looked at the QTLs associated with yield components under Fe toxic field conditions in particular in West Africa. Although of relatively small-effects, some of these QTLs co-located with previous QTLs, e.g., leaf bronzing QTL on chromosome 1, and were consistent over different experimental conditions, different environments and even in independent mapping studies.…”

“…As an alternative to Fe-toxic soil, the use of sand supplemented with different doses of FeSO 4 has been reported (Sikirou, 2009;Dufey et al, 2012). Onaga et al (2013) slightly improved this protocol by adding not only nitrogen, phosphorus and potassium but also micronutrients in the Yoshida solution.…”

“…Although of relatively small-effects, some of these QTLs co-located with previous QTLs, e.g., leaf bronzing QTL on chromosome 1, and were consistent over different experimental conditions, different environments and even in independent mapping studies. These stable QTLs were located in six regions of the rice genome and could be major QTLs harboring genes involved somehow in the tolerance to Fe toxicity (Dufey et al, 2012). Recently, Dufey et al (2015a) constructed an integrated map with the previous QTLs identified using the annotated physical map of the rice reference variety Nipponbare.…”

Bush Fallow and Cowpea Crop Use as Precedent and Organic Sources of Nutrients for Rice Cultivation on Acidic Plinthosol of Central Benin in West Africa

“…This results as two implications: incorporation of plant residues i) can help to correct Fe-deficient occurring in upland rice as chlorosis (rain-induced scorching), ii) increasing soil Fe content in upland can provoke contamination of lowland throughout runoff creating iron toxicity that is also a serious threat of rice [11]. From this analysis, we assert that the studied technology should be recommended for foot slope ecology because to limit the possible enrichment of subsequent lowland soil in Fe.…”

Markers-traits association for iron toxicity tolerance in selected Indonesian rice varieties

“…Introducing the traits of tolerant to iron toxicity from those varieties into the high yield popular varieties is the way to improved rice productivity in iron toxicity environment. Several study have been mapped on the rice genome related with traits involved in tolerance to Fe toxicity, under various environmental conditions and using different segregating populations issued from intra-specific populations (Dufey et al 2009(Dufey et al , 2012aShimizu 2009;Shimizu et al 2005;Wan et al 2003a, b;Wu et al 1997Wu et al , 1998Wu et al 2014) or interspecific (Dufey et al 2012b) crosses. These QTLs for traits directly or indirectly linked to iron toxicity tolerance have been localized but challenges of confident genomic localization remain huge, and with several hundred genes involved, their use in breeding programs is difficult.…”