Many survival and ecological problems have emerged in Pinus yunnanensis pure pine forest plantations that are usually assumed to be solved by creating mixed plantations. On this basis, we determined the physicochemical properties and enzyme activities of three soil layers in pure and three types of mixed P. yunnanensis plantation stands (admixed species: Alnus nepalensis, Celtis tetrandra, and Quercus acutissima) in Southwest China. We used one-way ANOVA with Tukey’s test to analyze the effects of plantation type and depth on the soil’s properties and variations among different depths. Principal component analysis combined with cluster analysis was used to evaluate the soil quality of different forest types comprehensively. The results showed that the stand with a mixing proportion of 2:1 of P. yunnanensis and A. nepalensis, C. tetrandra, and Q. acutissima had higher total porosity, moisture content, total nitrogen, available phosphorus, total phosphorus, sucrase, urease, and catalase enzyme activities than other proportions of mixed forest and P. yunnanensis pine pure forest. In general, the mixed P. yunnanensis plantation could improve the soil quality, especially its chemical properties and enzymes. This study provides a basis for creating a mixed-mode of P. yunnanensis and other tree species that can not only improve the economy of forest land but also enhance the ecological value.

Bark beetle, as a trunk borer, has caused a large number of tree deaths and seriously damaged the mountain forest ecosystem. Bark beetles oxidize the secondary metabolites of plants, degrade them, and excrete them from the body or convert them into components needed by the body. This process is completed by the cooperation of CYPs, GSTs, and CCEs and occurs in different tissues of the insects, including the gut (i.e., the part where beetle pheromone is produced and accumulated) and antennae (i.e., the olfactory organ used to sense defensive monoterpenes and other plant-related compounds and pheromones in the air). In this study, we identified and characterized three gene superfamilies of CYPs, GSTs, and CCEs involved in the detoxification of endobiotics (e.g., hormones and steroids) and xenobiotics (e.g., insecticides, sex pheromones, and plant allelochemicals) through a combination approach of bioinformatics, phylogenetics, and expression profiles. Transcriptome analyses led to the identification of 113 transcripts encoding 51 P450s, 33 GSTs, and 29 CCEs from Tomicus yunnanensis Kirkendall and Faccoli, 2008 (Coleoptera, Scolytinae). The P450s of T. yunnanensis were phylogenetically classified into four clades, representing the majority of the genes in the CYP3 clan. The CCEs from T. yunnanensis were separately grouped into five clades, and the GST superfamily was assigned to five clades. Expression profiles revealed that the detoxification genes were broadly expressed in various tissues as an implication of functional diversities. Our current study has complemented the resources for the detoxification genes in the family Coleoptera and allows for functional experiments to identify candidate molecular targets involved in degrading plants’ secondary metabolites, providing a theoretical basis for insect resistance in mixed forests.

Salt and low temperature are serious abiotic stresses and important constraints to agricultural productivity across the globe. These abiotic stresses negatively affect plant growth and physiological, biochemical, and molecular processes. Glycine betaine (GB) is an important osmoprotectant that enables plants to resist salinity, low temperature, and drought. GB can be synthesized in many organisms, including animals, plants, and bacteria. In higher plants, GB is synthesized through two-step oxidation of choline. However, rice, an important food crop, cannot synthesize GB. Thus, conferring the ability to synthesize GB to rice through genetic engineering is of great significance for enhancing its tolerance to abiotic stress. Recently, an enzyme, GSDMT (glycine, sarcosine, and dimethylglycine methyltransferase) was found in a diatom, Talassiosira pseudonana, and found able to catalyze the three successive methylation steps of glycine to form GB. This biosynthetic pathway for GB synthesis is also the simplest in living organisms. Here, the optimized codon of the TpGSDMT gene sequence was synthesized and cloned into an overexpression vector, pBWA(V)HS, which contains a CaMV 35S promoter, and then, the constructed vector was transferred into rice (Oryza sativa L. ssp. Japonica). The GB content in transgenic rice showing overexpression of TpGSDMT was significantly increased, and these transformants exhibited markedly enhanced tolerance to salt and low temperature. These results indicate that the TpGSDMT gene can be used for the genetic improvement in crop plants’ resistance to salinity and low temperature.

Phosphoethanolamine N-methyltransferase (PEAMT) is a key enzyme that catalyzes three successive methylation steps of phosphoethanolamine (P-EA) to phosphocholine (P-Cho). Meanwhile, P-Cho is a major precursor of phosphatidylcholine (PC) and glycine betaine (GB), which are involved in cell signal transduction, stress response, etc. Therefore, the PEAMT gene plays an essential role in plant growth and development as well as stress resistance. There are two homologous PEAMT genes in rice (Oryza sativa L. ssp. japonica), namely, OsPEAMT1 and OsPEAMT2. However, there has not been any comprehensive functional analysis of these two genes. Here, we employed bioinformatics methods to analyze the amino acid sequences and promoters of OsPEAMT1 and OsPEAMT2, and found that both proteins contain two methyltransferase domains. OsPEAMT1 is highly similar with ZmPEAMT, and OsPEAMT2 is closely related to LmPEAMT and TaPEAMT. There are abundant plant hormone response elements, stress response elements and low-temperature response elements in the promoters of OsPEAMT1 and OsPEAMT2. The in vitro enzymatic activity assays of recombinant proteins of OsPEAMT1 and OsPEAMT2 indicated that they can catalyze the production of P-Cho from P-EA, respectively. Meanwhile, the endogenous P-Cho content increased significantly (p < 0.05) when exogenous P-EA was added to rice. These indicate that OsPEAMT1 and OsPEAMT2 proteins have catalytic functions in vivo and in vitro. The expression patterns of both genes are different in different tissues, flowers and seeds at various developmental stages. Additionally, both genes have different responses to salt and low-temperature stress. This study supplies valuable insights into the function of OsPEAMT1 and OsPEAMT2, and it will provide key targets for rice molecular breeding, offering important insights for the development of rice with stress resistance and high yield.