Metabolomics of sorghum roots during nitrogen stress reveals compromised metabolic capacity for salicylic acid biosynthesis

Abstract

Sorghum ( Sorghum bicolor [L.] Moench) is the fifth most productive cereal crop worldwide with some hybrids having high biomass yield traits making it promising for sustainable, economical biofuel production. To maximize biofuel feedstock yields, a more complete understanding of metabolic responses to low nitrogen (N) will be useful for incorporation in crop improvement efforts. In this study, 10 diverse sorghum entries (including inbreds and hybrids) were field‐grown under low and full N conditions and roots were sampled at two time points for metabolomics and 16S amplicon sequencing. Roots of plants grown under low N showed altered metabolic profiles at both sampling dates including metabolites important in N storage and synthesis of aromatic amino acids. Complementary investigation of the rhizosphere microbiome revealed dominance by a single operational taxonomic unit ( OTU ) in an early sampling that was taxonomically assigned to the genus Pseudomonas . Abundance of this Pseudomonas OTU was significantly greater under low N in July and was decreased dramatically in September. Correlation of Pseudomonas abundance with root metabolites revealed a strong negative association with the defense hormone salicylic acid ( SA ) under full N but not under low N, suggesting reduced defense response. Roots from plants with N stress also contained reduced phenylalanine, a precursor for SA , providing further evidence for compromised metabolic capacity for defense response under low N conditions. Our findings suggest that interactions between biotic and abiotic stresses may affect metabolic capacity for plant defense and need to be concurrently prioritized as breeding programs become established for biofuels production on marginal soils.

Genome-wide identification of the amino acid permease genes and molecular characterization of their transcriptional responses to various nutrient stresses in allotetraploid rapeseed

“…Rapeseed has a high demand for N nutrients whereas it shows very low NUE [26,27]. Under N stresses, the metabolic profiles of AAs were significantly altered in plants [37]. Under nitrate limitation condition, 26 members of 34 BnaAAPs were differentially expressed in rapeseed plants compared with the condition of sufficient nitrate supply (Fig.…”

“…We performed the quantitative analysis of relative gene expression by using the SYBR® Premix Ex Taq™ II (Tli RNaseH Plus) (TaKaRa, Shiga, Japan) kit in an Applied Biosystems StepOne™ Plus Real-time PCR System (Thermo Fisher Scientific, Waltham, MA, USA). The thermal recycle regimes were as follows: 95°C for 3 min, followed by 40 cycles of 95°C for 10 s, then 60°C for 30 s [37]. We also conducted a melting curve analysis to ensure the primer specificity of target genes: 95°C for 15 s, 60°C for 1 min, and 60°C-95°C for 15 s (+ 0.3°C per cycle).…”

Feature selection and causal analysis for microbiome studies in the presence of confounding using standardization

“…Sorghum root production of OPDA is of primary interest due to OPDA having both independent plant defense functions and being an important precursor to Jasmonic acid, which functions in plant immune responses that are induced by beneficial bacteria (Van der Ent et al, 2009;Wasternack, 2014). The study analyzed here is part of an experiment described by Sheflin et al (2019); we subset on n = 34 samples collected in September across high and low nitrogen fertilizer. Rhizosphere microbiome data were collected using 16S amplicon sequencing and clustered at 97% sequence identity.…”

Insights into the metabolic responses of two contrasting Tibetan hulless barley genotypes under low nitrogen stress

“…Therefore, metabolic profiling could contribute significantly to the study of stress biology in plants [14]. Metabolomics approach has been employed to study various abiotic stresses including salinity, phosphorus, water, sulfur, oxidative and low-N stresses in plants [11,14,[15][16][17][18][19][20]. In hulless barley, metabolic profiling was conducted on salt stress, drought stress, and powdery mildew infection to uncover important pathways related to these stresses [21-23].…”