Short title: ODR1 Interacts with bHLH57 and Controls Seed Dormancy One-sentence summary: ODR1 negatively controls seed dormancy by interacting with the transcription factor bHLH57 and preventing its induction of NCED6 and NCED9 expression and ABA biosynthesis.

A seafood poisoning event occurred in Qinhuangdao, China, in April 2016. Subsequently, the causative mussels (Mytilus galloprovincialis) were harvested and analyzed to reveal a high concentration [∼10 758 μg of saxitoxin (STX) equiv kg] of paralytic shellfish toxins (PSTs), including gonyautoxin (GTX)1/4 and GTX2/3, as well as new metabolites 11-hydroxy-STX (M2), 11,11-dihydroxy-STX (M4), open-ring 11,11-dihydroxy-STX (M6), 11-hydroxy-neosaxitoxin (NEO) (M8), and 11,11-dihydroxy-NEO (M10). To understand the origin and biotransformation pathways of these new metabolites, uncontaminated mussels (M. galloprovincialis) were fed with either of two Alexandrium tamarense strains (ATHK and TIO108) under laboratory conditions. Similar PST metabolites were also detected in mussels from both feeding experiments. Results supposed that 11-hydroxy-C2 toxin (M1) and 11,11-dihydroxy-C2 (M3) are transformed from C2, while 11-hydroxy-C4 toxin (M7) and 11,11-dihydroxy-C4 (M9) are converted from C4. In addition, the metabolites M2, M4, and M6 appear to be products of GTX2/3, and the metabolites M8 and M10 are likely derived from GTX1/4.

Background Polyploidy, especially allopolyploidy, which entails merging divergent genomes via hybridization and whole-genome duplication (WGD), is a major route to speciation in plants. The duplication among the parental genomes (subgenomes) often leads to one subgenome becoming dominant over the other(s), resulting in subgenome asymmetry in gene content and expression. Polyploid wheats are allopolyploids with most genes present in two (tetraploid) or three (hexaploid) functional copies, which commonly show subgenome expression asymmetry. It is unknown whether a similar subgenome asymmetry exists during translation. We aim to address this key biological question and explore the major contributing factors to subgenome translation asymmetry. Results Here, we obtain the first tetraploid wheat translatome and reveal that subgenome expression asymmetry exists at the translational level. We further perform in vivo RNA structure profiling to obtain the wheat RNA structure landscape and find that mRNA structure has a strong impact on translation, independent of GC content. We discover a previously uncharacterized contribution of RNA structure in subgenome translation asymmetry. We identify 3564 single-nucleotide variations (SNVs) across the transcriptomes between the two tetraploid wheat subgenomes, which induce large RNA structure disparities. These SNVs are highly conserved within durum wheat cultivars but are divergent in both domesticated and wild emmer wheat. Conclusions We successfully determine both the translatome and in vivo RNA structurome in tetraploid wheat. We reveal that RNA structure serves as an important modulator of translational subgenome expression asymmetry in polyploids. Our work provides a new perspective for molecular breeding of major polyploid crops.

We present the carbon isotope ( 14 C and 13 C), dissolved inorganic carbon (DIC), and dissolved organic carbon (DOC) concentration measurements in the South China Sea (SCS) to reveal the different sources and cycling time scales of the two major carbon pools in the SCS. The DIC concentrations ranged from 1,776 to 2,328 μmol kg −1 , and they were lower at the surface and increased with depth. Conversely, the DOC concentrations ranged from 38 to 95 μM, and they were higher on the surface and decreased rapidly in the upper 500-m water depth. The DIC Δ 14 C and DOC Δ 14 C values varied from −227‰ to 68‰ and −557‰ to −258‰, respectively, and both decreased with depth until 1,500 m and then remained relatively constant. DOC Δ 14 C values were −330‰ lower than DIC Δ 14 C, indicating that DOC has cycled for much longer than DIC in the SCS. The lower Δ 14 C-DIC and Δ 14 C-DOC values at depths shallower than 700 m were mainly influenced by intensified vertical mixing, which upwelled the deep water with low Δ 14 C-DIC and Δ 14 C-DOC values for thorough mixture with the upper layer water. Conversely, the small difference in the Δ 14 C signature in deep water (>1,500 m) between the SCS and the North Pacific confirmed the rapid water exchange through the Luzon Strait and rapid water mixing in the SCS basin, which plays an important role in controlling carbon cycling in the deep SCS.Plain Language Summary Dissolved inorganic carbon (DIC) is the largest carbon pool in the ocean and is closely linked to dissolved organic carbon (DOC), which is the largest exchangeable organic carbon pool in the ocean. Both DIC and DOC play important roles in the global carbon cycle, but their sources, distribution, and cycling time are different and controlled by different processes in the ocean. Here we report radiocarbon and stable carbon isotope measurements of DIC and DOC collected in the South China Sea (SCS) to reveal the sources and cycling time scales of the two major carbon pools in the SCS. The Δ 14 C values and 14 C ages indicate that DOC has cycled for much longer than DIC in the SCS. The rapid water exchange and mixing between the SCS and the Kuroshio Current in the Northwestern Pacific play important roles in controlling the distributions and cycling of DIC and DOC in the SCS.