Transcriptome and Coexpression Network Analyses Provide In-Sights into the Molecular Mechanisms of Hydrogen Cyanide Synthesis during Seed Development in Common Vetch (Vicia sativa L.)

Abstract

The common vetch (Vicia sativa L.) seed is an ideal plant-based protein food for humans, but its edible value is mainly limited by the presence of cyanogenic glycosides that hydrolyze to produce toxic hydrogen cyanide (HCN), and the genes that regulate HCN synthesis in common vetch are unknown. In this study, seeds from common vetch at 5, 10, 15, 20, 25, 30, and 35 days after anthesis were sampled, and the seven stages were further divided into five developmental stages, S1, S2, S3, S4, and S5, based on morphological and transcriptome analyses. A total of 16,403 differentially expressed genes were identified in the five developmental stages. The HCN contents of seeds in these five stages were determined by alkaline titration, and weighted gene coexpression network analysis was used to explain the molecular regulatory mechanism of HCN synthesis in common vetch seeds. Eighteen key regulatory genes for HCN synthesis were identified, including the VsGT2, VsGT17 and CYP71A genes, as well as the VsGT1 gene family. VsGT1, VsGT2, VsGT17 and CYP71A jointly promoted HCN synthesis, from 5 to 25 days after anthesis, with VsGT1-1, VsGT1-4, VsGT1-11 and VsGT1-14 playing major roles. The HCN synthesis was mainly regulated by VsGT1, from 25 to 35 days after anthesis. As the expression level of VsGT1 decreased, the HCN content no longer increased. In-depth elucidation of seed HCN synthesis lays the foundations for breeding common vetch with low HCN content.

Designing Novel Strategies for Improving Old Legumes: An Overview from Common Vetch

“…Eighteen key regulatory genes that are involved in HCN biosynthesis have been identified. These genes would be crucial as molecular markers for the selection and breeding of low HCN levelled vetch germplasm [ 53 ]. In any case, and especially for non-ruminant diets, it seems that these ANFs present in common vetch seeds need to be reduced or partially inactivated by adequate grain processing methods.…”

Harnessing Knowledge from Plant Functional Genomics and Multi-Omics for Genetic Improvement

“…The transcriptome profiling of 42 ginseng ( Panax ginseng ) cultivars suggested that 22 candidate genes involved in ginsenoside Rb1 biosynthesis [ 40 ]. By combining time-series transcriptomic profiling with hydrogen cyanide (HCN) analysis of common vetch ( Vicia sativa L.) seeds [ 41 ], Li et al identified the main regulatory genes for HCN synthesis in common vetch seeds and established a co-expression network of HCN synthesis using the weighted gene coexpression network analysis (WGCNA). The RNA-seq data during cotton fiber elongation between Gossypium stocksii (purple fiber) and Gossypium arboreum (white fiber) revealed that the key PA biosynthetic genes are responsible for fiber coloration in G. stocksii , which improved our understanding in the molecular mechanisms of cotton fiber coloration [ 42 ].…”

Understanding the Complex Functional Interplay between Glucosinolates and Cyanogenic Glycosides in Carica papaya

“…In addition, the gene co-expression networks would facilitate identifying potential key genes [109] that contribute to the molecular mechanism of GSL and CG biosynthesis in papaya. Previous efforts have generated the gene coexpression network of CG and performed the qRT-PCR analysis to investigate the regulatory mechanism of hydrogen cyanide (HCN) synthesis, which could provide a molecular basis for breeding new cultivars with low HCN content in common vetch [110]. Additionally, the MEME motif profiles (Figures 6 and 7) also showed that these sequences exhibited three highly conserved motifs, Motif 1 (37 amino acids, red), Motif 3 (41 amino acids, green), and Motif 10 (15 amino acids, yellow); thus proposing the importance of these sequence fragments for the CG biosynthesis pathway, thus causing their preservation throughout the evolutionary process.…”

“…In addition, the gene co-expression networks would facilitate identifying potential key genes [109] that contribute to the molecular mechanism of GSL and CG biosynthesis in papaya. Previous efforts have generated the gene co-expression network of CG and performed the qRT-PCR analysis to investigate the regulatory mechanism of hydrogen cyanide (HCN) synthesis, which could provide a molecular basis for breeding new cultivars with low HCN content in common vetch [110].…”