The MYB Activator WHITE PETAL1 Associates with MtTT8 and MtWD40-1 to Regulate Carotenoid-Derived Flower Pigmentation in Medicago truncatula.

Carotenoids are a group of natural tetraterpenoid pigments with indispensable roles in the plant life cycle and the human diet. Although the carotenoid biosynthetic pathway has been well characterized, the regulatory mechanisms that control carotenoid metabolism, especially in floral organs, remain poorly understood. In this study, we identified an anthocyanin-related R2R3-MYB protein, WHITE PETAL1 (WP1), that plays a critical role in regulating floral carotenoid pigmentation in Medicago truncatula Carotenoid analyses showed that the yellow petals of the wild-type M. truncatula contained high concentrations of carotenoids that largely consisted of esterified lutein and that disruption of WP1 function via Tnt1 insertion led to substantially reduced lutein accumulation. WP1 mainly functions as a transcriptional activator and directly regulates the expression of carotenoid biosynthetic genes including MtLYCe and MtLYCb through its C-terminal acidic activation motif. Further molecular and genetic analyses revealed that WP1 physically interacts with MtTT8 and MtWD40-1 proteins and that this interaction facilitates WP1's function in the transcriptional activation of both carotenoid and anthocyanin biosynthetic genes. Our findings demonstrate the molecular mechanism of WP1-mediated regulation of floral carotenoid pigmentation and suggest that the conserved MYB-basic-helix-loop-helix-WD40 regulatory module functions in carotenoid biosynthesis in M. truncatula, with specificity imposed by the MYB partner.

HEADLESS, a WUSCHEL homolog, uncovers novel aspects of shoot meristem regulation and leaf blade development in Medicago truncatula.

The formation and maintenance of the shoot apical meristem (SAM) are critical for plant development. However, the underlying molecular mechanism of regulating meristematic cell activity is poorly understood in the model legume Medicago truncatula. Using forward genetic approaches, we identified HEADLESS (HDL), a homolog of Arabidopsis WUSCHEL, required for SAM maintenance and leaf development in M. truncatula. Disruption of HDL led to disorganized specification and arrest of the SAM and axillary meristems, resulting in the hdl mutant being locked in the vegetative phase without apparent stem elongation. hdl mutant leaves are shorter in the proximal-distal axis due to reduced leaf length elongation, which resulted in a higher blade width/length ratio and altered leaf shape, uncovering novel phenotypes undescribed in the Arabidopsis wus mutant. HDL functions as a transcriptional repressor by recruiting MtTPL through its conserved WUS-box and EAR-like motif. Further genetic analysis revealed that HDL and STENOFOLIA (STF), a key regulator of M. truncatula lamina outgrowth, act independently in leaf development although HDL could recruit MtTPL in the same manner as STF does. Our results indicate that HDL has conserved and novel functions in regulating shoot meristems and leaf shape in M. truncatula, providing new avenues for understanding meristem biology and plant development.

The evaluation of enteric-coated mycophenolate sodium in cardiac deceased donor liver transplant patients in China.

OBJECTIVE: The management of liver receivers requires intense immunosuppression to prevent graft rejection. Mycophenolate mofetil (MMF) is a common immunosuppressant but frequently suffer dose reduction for gastrointestinal adverse reactions (GI). Hence, the enteric-coated mycophenolate sodium (EC-MPS) is introduced as a substitute for MMF to reduce GI. The study was designed to investigate the efficacy, safety and exposure equation of EC-MPS in liver transplant patients in China. METHODS: Ninety-two liver receivers who administered EC-MPS or MMF as a primary immunosuppressant were enrolled in this single-center study and divided into MMF group and EC-MPC group, respectively. Efficacy and safety of EC-MPS were compared with MMF. The MPA exposure was measured at time 0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12 h after mean 4.5 days of EC-MPS treatment. An equation of limited time points for estimating serum MPA exposure of EC-MPS was established using multiple stepwise regression model. RESULTS: Data show an interpatient variation in MPA AUC, Cmax and Tmax. After a first dose of EC-MPS, the mean value of serum AUC0-12 h was 20.68 mg/L (SD 8.94, range 8.1-46.3). Cmax was 9.7 mg/L (SD 6.48, range 2.7-16.3); Tmax was 1.90 h (SD 0.97, range 0.5-4). The best equation for estimating the AUC was 6.0 1 4 + 0.946C2 + 0.606C3 + 1.154C4 + 2.479C6 + 5.07C12. Comparing with MMF, EC-MPS not only effectively maintained immunosuppression, but also had similar incidences of infection, renal dysfunction and hematological disorders. However, EC-MPS markedly improved GI, the incidence of GI was half of the MMF group. CONCLUSION: This analysis presented that EC-MPS is an effective and safe immunosuppressant as similar as MMF. The conversion of MMF to EC-MPS could be administered.

Influences of elevational gradient on flower size and number of Gentiana lawrencei var. farreri.

Plants can adapt to environmental changes by adjusting their functional traits and biomass allocation. The size and number of flowers are functional traits related to plant reproduction. Life history theory predicts that there is a trade-off between flower size and number, and the trade-off can potentially explain the adaptability of plants. Elevation gradients in mountains provide a unique opportunity to test how plants will respond to climate change. In this study, we tried to better explain the adaptability of the alpine plant Gentiana lawrencei var. farreri in response to climate change. We measured the flower size and number, individual size, and reproductive allocation of G. lawrencei var. farreri during the flowering period along an elevation gradient from 3200 to 4000 m, and explored their relationships using linear mixed-effect models and the structural equation model. We found that with elevation increasing, individual size and flower number decreased and flower size increased, while reproductive allocation remained unchanged. Individual size positively affected flower number, but was not related to flower size; reproductive allocation positively affected flower size, but was not related to flower number; there is a clear trade-off between flower size and number. We also found that elevation decreased flower number indirectly via directly reducing individual size. In sum, this study suggests that G. lawrencei var. farreri can adapt to alpine environments by the synergies or trade-offs among individual size, reproductive allocation, flower size, and flower number. This study increases our understanding of the adaptation mechanisms of alpine plants to climate change in alpine environments.

Complete chloroplast genome data of Ranunculus membranaceus (Ranunculaceae), an important medicinal plant species.

The perennial alpine herb Ranunculus membranaceus (Ranunculaceae) has significant medicinal value. The complete chloroplast genome of R. membranaceus was sequenced by high-throughput Illumina sequencing Platform Illumina NovaSeq 6000. The circular genome is 156,028 bp in size, including two inverted repeats (IRs) of 25,361 bp, a large single-copy (LSC) region of 85,491 bp, and a small single-copy (SSC) region of 19,815 bp. A total of 128 genes were annotated, namely 84 protein-coding genes (PCGs), 36 tRNA genes, and eight rRNA genes. Two phylogenetic trees of 18 species of the tribe Ranunculeae species were constructed with Meconopsis punicea as the outgroup based on the whole chloroplast genomes and the concatenated sequence of PCGs, respectively. Phylogeny showed that R. membranaceus was closely related to R. yunnanensis. These data enrich knowledge of Ranunculaceae genetics and will contribute to further studies of R. membranaceus in molecular breeding, genetic transformation, species identification, genetic engineering and phylogenetic research.

Personal exposure to PM2.5-bound heavy metals associated with cardiopulmonary function in general population.

To better understand the cardiopulmonary alterations associated with personal exposed PM2.5-bound heavy meals, we conducted a cross-sectional study in 2018 on 54 general residents. For each subject, PM2.5 exposure filter was collected by a low-volume sampler for 24 h; blood and urine samples were collected subsequently. Heavy metals in PM2.5, blood, and urine samples were determined by inductively coupled plasma mass spectrometry method. PM2.5-bound Mn, Cd, Sb, Pb, and Ni levels were 20.5, 9.27, 9.59, 28.3, and 16.9 ng/m3, respectively. The distribution of these metals followed the order: Pb (33.47%) > Mn (24.24%) > Ni (19.99%) > Sb (11.34%) > Cd (10.96%). The distribution of heavy meals in PM2.5, blood, and urine differed from each other. PM2.5-bound Cd, Pb levels were positively correlated with blood Cd, Pb levels (r = 0.323, r = 0.334, p < 0.05), respectively. PM2.5-bound Cd level was significantly higher in smoking group than non-smoking group (28.8 vs. 7.27 ng/m3, p < 0.01), same as Sb level (12.0 vs. 9.34 ng/m3, p < 0.01). Cd and Pb exposure might interact with cardiovascular function through autonomic regulation. No significant correlation was observed between metal exposure and pulmonary function. In conclusion, our data suggested that personal exposure to specific PM2.5-bound heavy metals might interact with profound cardiovascular alterations.