Prediction of Dhurrin Metabolism by Transcriptome and Metabolome Analyses in Sorghum

Abstract

Sorghum (Sorghum bicolor (L.)) Moench is an important food for humans and feed for livestock. Sorghum contains dhurrin which can be degraded into toxic hydrogen cyanide. Here, we report the expression patterns of 14 candidate genes related to dhurrin ((S)-4-Hydroxymandelnitrile-β-D-glucopyranoside) metabolism and the effects of the gene expression on specific metabolite content in selected sorghum accessions. Dhurrin-related metabolism is vigorous in the early stages of development of sorghum. The dhurrin contents of most accessions tested were in the range of approximately 6–22 μg mg−1 fresh leaf tissue throughout growth. The p-hydroxybenzaldehyde (pHB) contents were high at seedling stages, but almost nonexistent at adult stages. The contents of p-hydroxyphenylacetic acid (pHPAAc) were relatively low throughout growth compared to those of dhurrin or pHB. Generally, the expression of the candidate genes was higher at seedling stage than at other stages and decreased gradually as plants grew. In addition, we identified significant SNPs, and six of them were potentially associated with non-synonymous changes in CAS1. Our results may provide the basis for choosing breeding materials to regulate cyanide contents in sorghum varieties to prevent HCN toxicity of livestock or to promote drought tolerance or pathogen resistance.

Deciphering the Genetic Mechanisms of Salt Tolerance in Sorghum bicolor L.: Key Genes and SNP Associations from Comparative Transcriptomic Analyses

“…These changes may result from stress-induced alterations in the expression of genes involved in the biosynthesis and metabolism of cyanogenic glycosides. This can lead to a differential distribution of these compounds within the plant, potentially as a response to stress conditions [ 57 , 58 , 59 ]. Although the relationship between cyanogenic glycosides such as dhurrin and osmotic stress is not yet fully understood, it appears that they might play a role in plant defense mechanisms, possibly act as osmoprotectants, and have altered accumulation patterns under stress conditions.…”

Biosynthesis and Role of Dhurrin in Forage Sorghum

“…It is widely established that a high concentration of dhurrin is at the early vegetative growth stages [7,8,15,16]. The higher levels in young plants have been linked to a ready supply of N [17], expression of responsible genes [18] and the expression of enzyme-encoding genes CYP79A1 and CYP71E1, which are the highest at early crop growth stages [12]. The early growth stage is associated with active growth with canopy development which normally triggers increased uptake of nutrients from the soil.…”

OMICS in Fodder Crops: Applications, Challenges, and Prospects

“…The p-hydroxybenzaldehyde (pHB) was highest at the early growth stage and reduced with maturity. The candidate genes also showed an expression peak at the seedling stage and decreased at the adult stage [ 62 ]. The metabolic profile and expression of dhurrin metabolism genes in sorghum provide the criteria for selecting accession for fodder breeding programs to prevent HCN toxicity in livestock or promote drought tolerance or pathogen resistance.…”