Abstract
PurposeRhizodeposition shapes soil microbial communities that perform important processes such as soil C mineralization, but we have limited understanding of the plant genetic regions influencing soil microbes. Here, barley chromosome regions affecting soil microbial biomass-C (MBC), dissolved organic-C (DOC) and root biomass were characterised.MethodsA quantitative trait loci analysis approach was applied to identify barley chromosome regions affecting soil MBC, soil DOC and root biomass. This was done using barley Recombinant Chromosome Substitution Lines (RCSLs) developed with a wild accession (Caesarea 26-24) as a donor parent and an elite cultivar (Harrington) as recipient parent.ResultsSignificant differences in root-derived MBC and DOC and root biomass among these RCSLs were observed. Analysis of variance using single nucleotide polymorphisms genotype classes revealed 16 chromosome regions influencing root-derived MBC and DOC. Of these chromosome regions, five on chromosomes 2H, 3H and 7H were highly significant and two on chromosome 3H influenced both root-derived MBC and DOC. Potential candidate genes influencing root-derived MBC and DOC concentrations in soil were identified.ConclusionThe present findings provide new insights into the barley genetic influence on soil microbial communities. Further work to verify these barley chromosome regions and candidate genes could promote marker assisted selection and breeding of barley varieties that are able to more effectively shape soil microbes and soil processes via rhizodeposition, supporting sustainable crop production systems.
Highlights
Soil microbes mediate carbon (C) and organic matter cycling in soil, contributing a vital role for the regulation of C O2 emissions from soil (Prentice et al 2001; Li et al 2013) and nutrient release from soil organic matter (SOM) (Fontaine et al 2011; Dijkstra et al 2013; Alegria Terrazas et al 2016)
It is known that the growth of plants can alter this microbially mediated SOM decomposition to varying extents (e.g. Cheng et al 2003; Mwafulirwa et al 2016, 2021), with increases of up to 380% relative to unplanted soil reported by Cheng et al (2003)
In previous work (Mwafulirwa et al 2016), we showed that the activity of soil microbes was affected by barley variety, likely due to differences in rhizodeposit quality among the varieties or genotypes, which included genotypes used in the present study
Summary
Soil microbes mediate carbon (C) and organic matter cycling in soil, contributing a vital role for the regulation of C O2 emissions from soil (Prentice et al 2001; Li et al 2013) and nutrient release from soil organic matter (SOM) (Fontaine et al 2011; Dijkstra et al 2013; Alegria Terrazas et al 2016). The soil microbial communities and their interactions with plants are impacted by the release of a range of compounds from living roots through root exudation, sloughed cells, mucilage and so on, collectively defined as rhizodeposition (Jones et al 2004). These rhizodeposit compounds, in particular root exudates, are utilized by microbes as C sources to derive energy for their activity (Paterson 2003; Cheng and Kuzyakov 2005), with this resulting in the decrease or increase of SOM decomposition (Jenkinson et al 1985; Kuzyakov et al 2000; Yin et al 2019).
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