SummaryMetabolic profiling was carried out in the forage grass Lolium perenne L. (perennial ryegrass) to uncover mechanisms involved in the plants response to water stress. When leaf and root materials from two genotypes, with a contrasting water stress response, were analysed by GC-MS, a clear difference in the metabolic profiles of the leaf tissue under water stress was observed. Differences were principally due to a reduction in fatty acid levels in the more susceptible Cashel genotype and an increase in sugars and compatible solutes in the more tolerant PI 462336 genotype. Sugars with a significant increase included: raffinose, trehalose, glucose, fructose and maltose. Increasing the ability of perennial ryegrass to accumulate these sugars in response to a water deficit may lead to more tolerant varieties. The metabolomics approach was combined with a transcriptomics approach in the water stress tolerant genotype PI 462336, which has identified perennial ryegrass genes regulated under water stress.

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A prerequisite to exploiting soil microbes for sustainable crop production is the identification of the plant genes shaping microbiota composition in the rhizosphere, the interface between roots and soil. Here, we use metagenomics information as an external quantitative phenotype to map the host genetic determinants of the rhizosphere microbiota in wild and domesticated genotypes of barley, the fourth most cultivated cereal globally. We identify a small number of loci with a major effect on the composition of rhizosphere communities. One of those, designated the QRMC-3HS, emerges as a major determinant of microbiota composition. We subject soil-grown sibling lines harbouring contrasting alleles at QRMC-3HS and hosting contrasting microbiotas to comparative root RNA-seq profiling. This allows us to identify three primary candidate genes, including a Nucleotide-Binding-Leucine-Rich-Repeat (NLR) gene in a region of structural variation of the barley genome. Our results provide insights into the footprint of crop improvement on the plant’s capacity of shaping rhizosphere microbes.

Background and AimsImproving phosphorus (P) nutrient efficiency in Lolium perenne (perennial ryegrass) is likely to result in considerable economic and ecological benefits. To date, research into the molecular and biochemical response of perennial ryegrass to P deficiency has been limited, particularly in relation to the early response mechanisms. This study aimed to identify molecular mechanisms activated in response to the initial stages of P deficiency.MethodsA barley microarray was successfully used to study gene expression in perennial ryegrass and this was complemented with gas chromatography-mass spectrometry metabolic profiling to obtain an overview of the plant response to early stages of P deficiency.Key ResultsAfter 24 h of P deficiency, internal phosphate concentrations were reduced and significant alterations were detected in the metabolome and transcriptome of two perennial ryegrass genotypes. Results indicated a replacement of phospholipids with sulfolipids and the utilization of glycolytic bypasses in response to P deficiency in perennial ryegrass.ConclusionsThe transcriptome and metabolome of perennial ryegrass undergo changes in response to reductions in P supply after 24 h.