Mei (Prunus mume) is an ornamental woody plant that has been domesticated in East Asia for thousands of years. High diversity in floral traits, along with its recent genome sequence, makes mei an ideal model system for studying the evolution of woody plants. Here, we investigate the genetic architecture of floral traits in mei and its domestication history by sampling and resequencing a total of 351 samples including 348 mei accessions and three other Prunus species at an average sequencing depth of 19.3×. Highly-admixed population structure and introgression from Prunus species are identified in mei accessions. Through a genome-wide association study (GWAS), we identify significant quantitative traits locus (QTLs) and genomic regions where several genes, such as MYB108, are positively associated with petal color, stigma color, calyx color, and bud color. Results from this study shed light on the genetic basis of domestication in flowering plants, particularly woody plants.

The survival in freezing temperature for woody plants is exclusively dependent on the perception of coldness and induction of dormancy. CBF/DREB1 transcriptional factors join cold-response conduits and the DAM genes, especially PmDAM6, are well-known regulators of dormancy. Despite the immense importance, little is documented on the association between CBF proteins and the complexity of the promoter region in PmDAM6 with the function of bud dormancy in P. mume. Therefore, this study was based on the cloning of PmDAM6 and six PmCBFs to evaluate their integral roles in the process of bud development. The consistency of expressions in either vegetative or reproductive buds provided a negative control from PmCBFs to PmDAM6 during the onset of dormancy. Besides, PmCBF5 could form heteromeric complexes with PmDAM1 and PmDAM6. PmCBF1, PmCBF3, and PmDAM4 recognized the promoter of PmDAM6 by the alternative binding sites. Therefore, the interactions of these genes formulated the base of an obvious model to respond to the coldness and engendered dormancy release. Findings of this study will further help the unveil the genetic control of bud dormancy and its augmentation in P. mume and may offer an explanation for the vernalization.

SQUAMOSA promoter-binding protein (SBP)-box family genes encode plant-specific transcription factors that play crucial roles in plant development, especially flower and fruit development. However, little information on this gene family is available for Prunus mume, an ornamental and fruit tree widely cultivated in East Asia. To explore the evolution of SBP-box genes in Prunus and explore their functions in flower and fruit development, we performed a genome-wide analysis of the SBP-box gene family in P. mume. Fifteen SBP-box genes were identified, and 11 of them contained an miR156 target site. Phylogenetic and comprehensive bioinformatics analyses revealed that different groups of SBP-box genes have undergone different evolutionary processes and varied in their length, structure, and motif composition. Purifying selection has been the main selective constraint on both paralogous and orthologous SBP-box genes. In addition, the sequences of orthologous SBP-box genes did not diverge widely after the split of P. mume and Prunus persica. Expression analysis of P. mume SBP-box genes revealed their diverse spatiotemporal expression patterns. Three duplicated SBP-box genes may have undergone subfunctionalization in Prunus. Most of the SBP-box genes showed high transcript levels in flower buds and young fruit. The four miR156-nontargeted genes were upregulated during fruit ripening. Together, these results provide information about the evolution of SBP-box genes in Prunus. The expression analysis lays the foundation for further research on the functions of SBP-box genes in P. mume and other Prunus species, especially during flower and fruit development.

Dormancy Associated MADS-box genes are SVP/MADs-box members and supposed to play crucial roles in plant dormancy of perennial species. In Prunus mume, PmDAM6 has been previously identified to induce plant dormancy. In the current study, six PmDAMs were cloned in P. mume and functionally analyzed in yeast and tobacco to detect the roles of the genes paralogous to PmDAM6. The expression patterns together with sequence similarities indicate that PmDAMs are divided into two sub-clades within SVP group. Moreover, PmDAMs are verified to take part in the development of different plant organs, specifically the flower buds, in some intricate patterns. Furthermore, the PmDAM proteins are found to have special functions by forming corresponding protein complex during the development of flower bud and induction of dormancy. In particular, when PmDAM1 dominating in flower bud in the warm months, the protein complexes are consisted of PmDAM1 itself or with PmDAM2. With the decrease temperatures in the following months, PmDAM6 was found to be highly expressed and gradually changed the complex structure to PmDAM6-protein complex due to strong binding tendencies with PmDAM1 and PmDAM3. Finally, the homodimers of PmDAM6 prevailed to induce the dormancy. The results obtained in the current study highlight the functions of PmDAMs in the tissue development and dormancy, which provide available suggestions for further explorations of protein-complex functions in association with bud growth and dormancy.

The present study focuses on characterization of two hemicellulases, RuXyn1 and RuXyn2, from rumen bacterial metagenome and their capabilities for degradation of xylans. Glycosyl hydrolase (GH) family 43 β-D -xylosidase/α-L -arabinofuranosidase RuXyn1 can hydrolyze p-nitrophenyl-β-D -xylopyranoside (pNPX), p-nitrophenyl-α-L -arabinofuranoside (pNPA), and xylo-oligosaccharide substrates, while GH30 1,5-α-L -arabinofuranosidase/β-D -xylosidase RuXyn2, the first α-L -arabinofuranosidase assigned to this GH family, shows activities towards 1,5-α-L -arabinobiose and pNPX substrates but no activity for pNPA. Kinetic analysis for aryl-glycosides revealed that RuXyn2 had higher catalytic efficiency than RuXyn1 toward pNPX substrate. RuXyn1 shows high synergism with endoxylanase, elevating by 73% the reducing sugars released from brichwood xylans, and converted most intermediate xylo-oligosaccharide hydrolysate into xylose. The high xylose conversion capability of RuXyn1 suggests it has potential applications in enzymatic production of xylose and improvement of hemicellulose saccharification for production of biofuels. RuXyn2 shows no obviously synergistic effect in the endoxylanase-coupled assay for enzymatic saccharification of xylan. Further cosmid DNA sequencing revealed a neighboring putative GH43 α-L -arabinofuranosidase RuAra1 and two putative GH3 β-xylosidase/arabinosidases, RuXyn3 and RuXyn5, downstream of RuXyn2, indicating that this hemicellulase gene cluster may be responsible for production of end-product, xylose and arabinose, from hemicellulose biomass.

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Plants facing the seasonal variations always need a growth restraining mechanism when temperatures turn down. C-repeat binding factor (CBF) genes work essentially in the cold perception. Despite lots of researches on CBFs, the multiple crosstalk is still interesting on their interaction with hormones and dormancy-associated MADS (DAM) genes in the growth and dormancy control. Therefore, this study highlights roles of PmCBFs in cold-induced dormancy from different orgens. And a sense-response relationship between PmCBFs and PmDAMs is exhibited in this process, jointly regulated by six PmCBFs and PmDAM4–6. Meantime, GA3 and ABA showed negative and positive correlation with PmCBFs expression levels, respectively. We also find a high correlation between IAA and PmDAM1–3. Finally, we display the interaction mode of PmCBFs and PmDAMs, especially PmCBF1-PmDAM1. These results can disclose another view of molecular mechanism in plant growth between cold-response pathway and dormancy regulation together with genes and hormones.

Background: Coke oven workers are regularly exposed to coke oven emissions (COE) and may be at risk of developing lung diseases. There is limited evidence for the link between exposure to COE and chronic obstructive pulmonary diseases (COPD). The aim of this study was to explore the dose-response relationship between COE exposure and COPD and to assess the interaction with cigarette smoking. Methods: Seven hundred and twelve coke oven workers and 211 controls were investigated in southern China. Benzene soluble fraction (BSF) concentrations as a surrogate of COE were measured in representative personal samples and the individual cumulative COE exposure level was quantitatively estimated. Detailed information on smoking habits and respiratory symptoms was collected and spirometric tests were performed. Results: The mean BSF levels at the top of two coking plants were 743.8 and 190.5 mg/m 3 , respectively, which exceed the OSHA standard (150 mg/m 3 ). After adjusting for cigarette smoking and other risk factors, there was a significant dose-dependent reduction in lung function and increased risks of chronic cough/phlegm and COPD in coke oven workers. The odds ratio for COPD was 5.80 (95% confidence interval 3.13 to 10.76) for high level cumulative COE exposure (>1714.0 mg/m 3 -years) compared with controls. The interaction between COE exposure and smoking in COPD was significant. The risk of COPD in those with the highest cumulative exposure to COE and cigarette smoking was 58-fold compared with non-smokers not exposed to COE. Conclusion: Long term exposure to COE increases the risk of an interaction between COPD and cigarette smoking.