Transcriptomic and metabolomic analysis provides insights into lignin biosynthesis and accumulation and differences in lodging resistance in hybrid wheat

Hybrid wheat is considered to be one way to improve the yield in the future. However, their higher plants height increased the lodging risk to some extent. In this study, two hybrid combinations with different lodging-resistance were used to analyze the stem-related traits during filling stage, and try to reveal the formation mechanism of difference in lodging-resistance by the lignin synthesis analysis of the basal second internode (BSI). The stem-related traits such as the breaking strength, stem pole substantial degree (SPSD), rind penetration strength (RPS) as well as the lignin content of lodging-resistance combination (LRC) were significantly higher than those of lodging-sensitive combination (LSC). The phenylpropanoid biosynthesis pathway was significantly and simultaneously enriched through the transcriptomics and metabolomics analysis at the later filling stage. A total of 35 critical regulatory genes involved in the phenylpropanoid pathway were identified. Moreover, 42% of identified genes were significantly and differentially expressed at the later grain filling stage between the two combinations, among which more than 80% were strongly up-regulated at the later grain filling stage in the LRC when compared with LSC. On the contrary, the LRC displayed lower content of lignin intermediate metabolites than the LSC. It is concluded that the key to the lodging-resistance formation of LRC is largely owing to the higher lignin synthesis at the later grain filling stage. Finally, the breeding strategies for synergistically improving plant height and lodging-resistance of hybrid wheat were put forward by comparing with the conventional wheat applied in large areas.