Abstract
BackgroundManganese (Mn) has several essential functions in plants, including a role as cofactor in the oxygen evolving complex (OEC) of photosystem II (PSII). Manganese deficiency is a major plant nutritional disorder in winter cereals resulting in significant yield reductions and winter kill in more severe cases. Among the winter cereals, genotypes of winter barley are known to differ considerably in tolerance to Mn deficiency, but the genes controlling the Mn deficiency trait remains elusive.ResultsExperiments were conducted using 248 barley varieties, cultivated in six distinct environments prone to induce Mn deficiency. High-throughput phenotyping for Mn deficiency was performed by chlorophyll a (Chl a) fluorescence analysis to quantify the quantum yield efficiency of PSII. High-throughput phenotyping in combination with ICP-OES based multi-element analyses allowed detection of marker-trait associations by genome wide association (GWA) mapping. Several key candidate genes were identified, including PSII subunit proteins, germin like proteins and Mn superoxide dismutase. The putative roles of the encoded proteins in Mn dependent metabolic processes are discussed.ConclusionsFifty-four candidate genes were identified by Chl a fluorescence phenotyping and association genetics. Tolerance of plants to Mn deficiency, which is referred to as Mn efficiency, appeared to be a complex trait involving many genes. Moreover, the trait appeared to be highly dependent on the environmental conditions in field. This study provides the basis for an improved understanding of the parameters influencing Mn efficiency and is valuable in future plant breeding aiming at producing new varieties with improved tolerance to cultivation in soil prone to induce Mn deficiency.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3129-9) contains supplementary material, which is available to authorized users.
Highlights
Manganese (Mn) has several essential functions in plants, including a role as cofactor in the oxygen evolving complex (OEC) of photosystem II (PSII)
The objectives of the current study were: to induce Mn deficiency in a collection of 248 European winter barley varieties cultivated under field and greenhouse conditions, to determine the variation in Mn efficiency by chlorophyll a (Chl a) fluorescence and leaf tissue Mn concentrations by Inductively coupled plasma - optical emission spectrometry (ICP-OES), and subsequently to carry out a genome wide association (GWA) in order to provide a set of single nucleotide polymorphism (SNP) associated with the trait, followed by the identification of candidate genes involved in Mn efficiency
The combination of Chl a fluorescence analysis and GWA approaches used in the current study has unravelled a series of main components contributing to the polygenic trait for Mn efficiency and paves the way for a better genetic characterization of the trait
Summary
Manganese (Mn) has several essential functions in plants, including a role as cofactor in the oxygen evolving complex (OEC) of photosystem II (PSII). Deficiency of the essential micronutrient manganese (Mn) remains an unsolved problem that has a severe impact on crop production worldwide [1,2,3,4]. In addition to substantial yield losses, suboptimal use of nitrogen, phosphorus and water are marked side-effects of Mn deficiency. It is prevalent in areas with well aerated and Leplat et al BMC Genomics (2016) 17:775 instantaneously made unavailable by oxidation to MnO2, due to soil chemical conditions [5]. A second way for farmers to fight Mn deficiency induced yield losses is by deploying plant varieties with an improved tolerance to growth in soils with low Mn availability, defined as Mn efficient varieties [3, 12]. Improving nutrient efficiencies by exploiting genetic diversity in plants and strategies to implement such traits into crop breeding have previously been suggested to improve plant productivity [13,14,15,16]
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