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Abstract Background Suspension culture is widely used in the establishment of efficient plant regeneration systems, as well as in the mass production of plant secondary metabolites. However, the establishment of a suspension culture system of Cunninghamia lanceolata is genotype-dependent given that proembryogenic masses (PEMs) are prone to browning during this process in recalcitrant genotypes. Previously, we reported that the plant peptide hormone phytosulfokine (PSK) can tremendously decrease the hydrogen peroxide (H2O2) level and help to initiate somatic embryogenesis (SE) in recalcitrant C. lanceolata genotypes. However, to date, no studies have revealed whether or how PSK may contribute to the establishment of a suspension culture system in these recalcitrant genotypes. Results Here, we demonstrated that exogenous application of PSK effectively inhibited PEM browning during suspension culture in a recalcitrant genotype of C. lanceolata. Comparative time-series transcriptome profiling showed that redox homeostasis underwent drastic fluctuations when PEMs were cultured in liquid medium, while additional PSK treatment helped to maintain a relatively stable redox homeostasis. Interestingly, PSK seemed to have a dual effect on peroxidases (PRXs), with PSK simultaneously transcriptionally repressing ROS-producing PRXs and activating ROS-scavenging PRXs. Furthermore, determination of H2O2 and MDA content, as well as cell viability, showed that exogenous PSK treatment inhibited PEM browning and safeguarded PEM suspension culture by decreasing the H2O2 level and increasing PEM activity. Conclusions Collectively, these findings provide a valuable tool for the future establishment of large-scale C. lanceolata PEM suspension culture without genotype limitations.

Abstract Background Cunninghamia lanceolata (Chinese fir), a member of the conifer family Cupressaceae, is one of the most popular cultivated trees for wood production in China. Continuous research is being performed to improve C. lanceolata breeding values. Given the high rate of seed abortion (one of the reasons being the failure of ovule and pollen development) in C. lanceolata, the proper formation of female/male cones could theoretically increase the number of offspring in future generations. MIKC MADS-box genes are well-known for their roles in the flower/cone development and comprise the typical/atypical floral development model for both angiosperms and gymnosperms. Results We performed a transcriptomic analysis to find genes differentially expressed between female and male cones at a single, carefully determined developmental stage, focusing on the MIKC MADS-box genes. We finally obtained 47 unique MIKC MADS-box genes from C. lanceolata and divided these genes into separate branches. 27 out of the 47 MIKC MADS-box genes showed differential expression between female and male cones, and most of them were not expressed in leaves. Out of these 27 genes, most B-class genes (AP3/PI) were up-regulated in the male cone, while TM8 genes were up-regulated in the female cone. Then, with no obvious overall preference for AG (class C + D) genes in female/male cones, it seems likely that these genes are involved in the development of both cones. Finally, a small number of genes such as GGM7, SVP, AGL15, that were specifically expressed in female/male cones, making them candidate genes for sex-specific cone development. Conclusions Our study identified a number of MIKC MADS-box genes showing differential expression between female and male cones in C. lanceolata, illustrating a potential link of these genes with C. lanceolata cone development. On the basis of this, we postulated a possible cone development model for C. lanceolata. The gene expression library showing differential expression between female and male cones shown here, can be used to discover unknown regulatory networks related to sex-specific cone development in the future.

Abstract Background The side reactions of dehalogenation or C–N coupling tend to occur when halogenated aromatic amines are prepared by catalytic hydrogenation reduction of halogenated aromatic nitro compounds. In this paper, we prepared the sub-microspherical Fe3O4@PDA-Pd NPs catalyst apply it efficiently in the hydrogenation reduction of halogenated aromatic nitro compounds to prepare the halogenated aromatic amines under atmospheric pressure. The catalyst shows a high selectivity of greater than 96% and can effectively inhibit the occurrence of the side reactions of dehalogenation and C–N coupling. Results The optimum condition of the hydroreduction reaction is when tetrahydrofuran is used as solvent and the reaction happens at 50 °C for 5 h. The selectivity of the chlorinated aromatic amine and the fluorinated aromatic amine products exceed 99% and the yield exceeds 90%. Only a small amount of dehalogenated products and C–N coupling by-products were produced in the brominated aromatic compound and the iodinated aromatic compound. Conclusion We developed a promising method for preparing the superparamagnetic and strongly magnetic Fe3O4@PDA core–shell sub-microsphere-supported nano-palladium catalyst for catalyzing the hydrogenation reduction of halogenated aromatic nitro compounds. The halogenated aromatic amines were efficiently and highly selectively prepared under atmospheric pressure, with the side reactions of dehalogenation and C–N coupling effectively inhabited simultaneously.