Post-transcriptional regulation dominates protein biosynthesis in Landoltia punctata under biogas slurry stress

Xin-Li Gong¹Le-Le Zhou¹Cheng Ran¹Tian Zhou¹Huan-Huan Su¹Ting-Ting Lu¹Shi-Lin Zhang¹Jia-Zhou Li^2*Jun-Yi Li^1*

• ¹Heyuan Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Heyuan 517000, China, Heyuan, China
• ²Institute of Animal Science Guangdong Academy of Agricultural Sciences, State key aboratory of Livestock and Poultry Breeding, No.1 Dafeng Street, Wushan Road, Tianhe District, Guangzhou, 510640, Guangdong, China

Duckweed represents a promising alternative protein source, and enhancing both its protein content and stability is essential for large-scale applications. This study investigated the effects of high nitrogen and phosphorus stress from biogas slurry on protein accumulation in Landoltia punctata and the underlying molecular mechanisms. Supplementing Hoagland medium with 4% pig farm biogas slurry significantly increased the crude protein content from 18.13% to 24.18% (P<0.01). Integrated transcriptomic and proteomic analyses revealed a low overall correlation between mRNA and protein expression (R=0.1387), indicating that post-transcriptional regulation dominates protein accumulation. Notably, ribosomal pathway proteins showed no significant transcriptional changes but were markedly upregulated at the protein level, suggesting enhanced translation efficiency drives protein synthesis. Concurrently, downregulation of key amino acid catabolism enzymes reduced nitrogen source consumption, conserving substrates for protein synthesis. Furthermore, the photosynthetic system underwent adaptive reprogramming. Coordinated downregulation of light-responsive core genes and transcriptional suppression of carbon fixation pathway genes at both levels indicate a redirection of carbon and energy flows towards nitrogen assimilation and amino acid biosynthesis. This shift provides necessary precursors and energy for increased protein accumulation. Collectively, this study is the first to elucidate, from a multi-omic perspective, the pivotal role of post-transcriptional regulation in biogas slurry-induced protein accumulation in duckweed, offering a theoretical foundation for its molecular breeding and industrial application.