The chemical linkage between α-cellulose and lignin in plant cell walls has long been a controversial topic and crucial to devising effective strategies for sustainable biomass and bioenergy utilization. In this new contribution, we surveyed 80 Poaceae (Gramineae) species grown in tropical Hainan Island (China) to test the hypothesis that the presence of oxygen-containing chemical linkage in Poaceae species is widespread. Our innovative natural abundance oxygen isotopic analysis allowed us to infer that more than 1/3 of the species investigated has chemical (ether) linkages between α-cellulose and lignin in their leaf cell walls, with a species-specific 2–89 oxygen-containing bonds for every 1000 glucose units. However, the presence of such linkage appears to be phylogeny-dependent. On average, species of C3 photosynthetic mode are found to have more extensive oxygen-containing linkages than those of C4 photosynthetic mode. Our finding challenges the conventional view that no chemical bonds between α-cellulose and lignin are present in higher plant cell walls and calls for new strategies for further understanding of the chemical linkage between the two major constituents of cell walls. This is especially important in the context of renewed and growing interests in biomass, bioenergy, and plant cell wall structure studies.
To explore variation patterns of uptake, translocation, and accumulation processes responding to organophosphate esters (OPEs) among Poaceae plants, hydroponic and computer simulation experiments were executed. Plant growth, OPEs’ concentration, and bioinformation and transcript of lipid transporters in the three terrestrial barley, wheat, and maize and aquatic rice seedlings were studied after exposure to seven OPE congeners. Four types of plants could accumulate seven OPE congeners. OPEs could promote rice growth by upregulating IAA27 hormone gene. However, maize growth was inhibited due to upregulating IAA17 hormone gene. In general, OPEs with log K ow > 4 tended to accumulate in roots of the four types of plants. Furthermore, the uptake, translocation, and accumulation mechanism of OPEs in different plants showed species-specific, depending on chemical properties of OPEs and biological factors specifically referring to the binding ability and gene expression of lipid transporters. The uptake and accumulation of OPE in aquatic rice roots were mainly influenced by biological factors. On the contrary, terrestrial plants relied on log K ow more than biological factors. Meanwhile, TIL of Poaceae plants could be a common and key protein that contributed to OPEs accumulation.