Metabolites and Plant Hormones Related to the Resistance Response to Feeding Stimulation and Leaf Clipping Control in Chinese Pine (Pinus tabuliformis Carr.).

This experiment was conducted to define changes in metabolic pathways in response to mandibulate insect feeding and to provide a reference for further investigation of the molecular mechanisms underlying the development of conifer resistance. Chinese pine (Pinus tabuliformis Carr.) in good growth status in natural condition was chosen for stimulation by 10 pine caterpillars (Dendrolimus tabulaefomis Tsai et Liu) as feeding stimulation (FS), leaf clipping control (LCC) as mechanical damage, and CK group (with no treatment) (recorded as 0 h). The metabolome and total flavonoid content were measured in the needles at 0, 2, and 8 h after treatment. Plant hormones were measured with needles at 0, 0.5, 1, 1.5, 2, 4, 6, and 8 h after different treatments. The results show that a total of 30.8% flavonoids are identified by metabolomics analysis. Compared with leaf clipping control, feeding stimulation of Chinese pine caterpillars significantly induced the upregulation of metabolites in the flavonoid pathway in Chinese pine, and the plant hormones JA and IAA showed expression trends consistent with those of the metabolome. According to the biological processes of the four plant hormones involved, JA and SA are mostly involved in resistance formation, and in this study, both of them also have fluctuating expressions influenced by feeding stimulation, while the expressions of the growth-related hormones IAA and ABA have no significant changes at other time points except for 1 h after treatment. Thus, the flavonoid pathway is one of the main pathways involved in resistance formation in conifers, and JA and IAA are involved in the formation of resistance.

Midgut transcriptome analysis of Clostera anachoreta treated with lethal and sublethal Cry1Ac protoxin.

Clostera anachoreta is one of the important Lepidoptera insect pests in forestry, especially in poplars woods in China, Europe, Japan, and India, and so forth, and also the target insect of Cry1Ac toxin and Bt plants. Six genes, HSC70, GNB2L/RACK1, PNLIP, BI1-like, arylphorin type 2, and PKM were found in this study, and they might be associated with the response to the Cry1Ac toxin, found by analyzing the transcriptome data. And the PI3K-Akt pathway was highly enriched in differentially expressed unigenes and linked to several crucial pathways, including the B-cell receptor signaling pathway, toll-like receptor pathway, and mitogen-activated protein kinase signaling pathway. They might be involved in the recovery stage of the damaged midgut during the response to sublethal doses of Cry1Ac toxin. This is the first study conducted to specifically investigate C. anachoreta response to Cry toxin stress using large-scale sequencing technologies, and the results highlighted some important genes and pathways that could be involved in Btcry1Ac resistance development or could serve as targets for biologically based control mechanisms of this insect pest.

Simultaneous Determination of Salicylic Acid, Jasmonic Acid, Methyl Salicylate, and Methyl Jasmonate from Ulmus pumila Leaves by GC-MS.

Salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate are important phytohormones and defensive signaling compounds, so it is of great importance to determine their levels rapidly and accurately. The study uses Ulmus pumila leaves infected by Tetraneura akinire Sasaki at different stages as materials; after extraction with 80% methanol and ethyl acetate and purification with primary secondary amine (PSA) and graphitized carbon blacks (GCB), the contents of signal compounds salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate were determined by GC-MS. The results showed that the level of salicylic acid, jasmonic acid, methyl salicylate, and methyl jasmonate increased remarkably in U. pumila once infected by T. akinire Sasaki, but the maximums of these four compounds occurred at different times. Salicylic acid level reached the highest at the early stage, and jasmonic acid level went to the maximum in the middle stage; by contrast, change of content of methyl salicylate and methyl jasmonate was the quite opposite.

[Characteristics of soil seed banks in logging gaps of forests at different succession stages in Changbai Mountains].

An investigation was made on the soil seed banks in the logging gaps of Populus davidiana--Betula platyphylla secondary forest, secondary broad-leaved forest, and broad-leaved Korean pine mixed forest at their different succession stages in Changbai Mountains. Among the test forests, secondary broad-leaved forest had the highest individual density (652 ind x m(-2)) in its soil seed bank. With the succession of forest community, the diversity and uniformity of soil seed bank increased, but the dominance decreased. The seed density of climax species such as Pinus koraiensis, Abies nephrolepis, and Acer mono increased, whereas that of Maackia amurensis and Fraxinus mandshurica decreased. Moreover, the similarity in species composition between soil seed bank and the seedlings within logging gaps became higher. The individual density and similarity between soil seed bank and the seedlings in non-logging gaps were similar to those in logging gaps. All of these indicated that soil seed bank provided rich seed resources for forest recovery and succession, and the influence of soil seed bank on seedlings regeneration increased with the succession.

[Arthropod communities in jujube-grain intercropping system: composition and time series dynamics].

In order to reveal the correlations between the arthropod communities in two sub-systems (jujube yard and grain field) of jujube-grain intercropping system, an investigation was conducted on the composition and time series dynamics of the communities in the two sub-systems. A total of 14 936 arthropod individuals belonging to 14 orders and 96 families were found, among which, 5992 individuals of 14 orders and 82 families were in jujube yard and 8971 of 14 orders and 80 families were in grain field, and some differences were observed in the arthropod community structure between the two sub-systems. The time series dynamics of the arthropod communities could be divided into four periods, according to the optimal cut-apart of time series, i.e., decline period in grain field sub-system, species number increase period in whole system, steady period in whole system, and decline period in whole system. The primary natural enemies in the system showed a characteristic of transferring between the two sub-systems in the four periods, and the parasitical natural enemies in a sub-system could impact the pest insects in another sub-system. The species transferring and mutual effect of the arthropod communities between the two sub-systems could benefit the stability of the jujube-grain intercropping system, and the capability of the system in controlling pest insects.

[Insect community and its relationship with Ceroplastes japonicus occurrence in jujube orchards].

Employing community character indices and canonical correlation analysis, this paper studied the insect communi structure and its relationship with the occurrence degree of Ceroplastes japonicus in jujube orchards. The results showed that based on the community discrepancy coefficient of 0.20, the insect community in various sampling fields could be categorized into two groups, i. e. , plain and hill. The occurrence of C. japonicus in plain region was heavier, with lower insect community diversity, smaller species number, and higher dominance of phytophagous insects, while that in hill region was lighter, with higher insect community diversity, more abundant species, and higher dominance of natural enemy insects. Canonical correlation analysis indicated that at the significant level of 0.05, the first and second pairs of canonical correlation coefficients of C. japonicus occurrence characters and insect community characters were 0. 9904 and 0.8538, respectively, suggesting that the occurrence of C.japonicus was significantly correlated with the characters of insect community. Community diversity (with the coefficient of 3. 4893), species number (with the coefficient of 5.8060), and dominance (with the coefficient of 6.9353) had most important effects on the occurrence of C. japonicus.

[Influence of temperature on insect-resistance of transgenic hybrid poplar 741].

The study showed that the insect-resistance of transgenic hybrid poplar 741 was closely related with temperature. The total mortality and accumulative mortality of Gypsy moth (Lmantriadispar L.) larvae increased with increasing temperature, and the sensitivity of larvae to the clones of transgenic hybrid poplar 741 and temperature decreased gradually with the increasing instars. Temperature had a promotion to the development of larvae fed on CK. When the temperature was high, the development of larvae quickened, the development period shortened, and the weight increasing rate and the frass increasing quantity quickened, but the development rate of larvae fed on transgenic hybrid poplar 741 was not obvious with varied temperature. The regressive equation of temperature and Clostera anachoreta (Fabricius) mortality during 1998-2000 year indicated that high resistant and medium resistant clones' temperature-insect mortality curve presented an obvious regressive relation.