Continuous cropping changes soil physiochemical parameters, enzymes and microorganism communities, causing “replant problem” in strawberry cultivation. We hypothesized that soil nematode community would reflect the changes in soil conditions caused by long-term continuous cropping, in ways that are consistent and predictable. To test this hypothesis, we studied the soil nematode communities and several soil parameters, including the concentration of soil phenolic acids, organic matter and nitrogen levels, in strawberry greenhouse under continuous-cropping for five different durations. Soil pH significantly decreased, and four phenolic acids, i.e., p-hydroxybenzoic acid, ferulic acid, cinnamic acid and p-coumaric acid, accumulated with time under continuous cropping. The four phenolic acids were highly toxic toAcrobeloidesspp., the eudominant genus in non-continuous cropping, causing it to reduce to a resident genus after seven-years of continuous cropping. Decreased nematode diversity indicated loss of ecosystem stability and sustainability because of continuous-cropping practice. Moreover, the dominant decomposition pathway was altered from bacterial to fungal under continuous cropping. Our results suggest that along with the continuous-cropping time in strawberry habitat, the soil food web is disturbed, and the available plant nutrition as well as the general health of the soil deteriorates; these changes can be indicated by soil nematode community.

Cacopsylla chinensis (Yang and Li) (Hemiptera: Psyllidae) is an important pest of pear in China. As an alternative to conventional chemical pesticides, botanicals including essential oils and their constituents could provide an eco-friendly and nonhazardous control method. In this study, the essential oil of clove buds ( Syzygium aromaticum ) was obtained by hydrodistillation. Five constituents, accounting for 99.89% of the oil, were identified by gas chromatography-mass spectrometry, and the major constituents were eugenol (88.61%) and eugenol acetate (8.89%), followed by β -caryophyllene (1.89%). In a laboratory bioassay, clove essential oil, commercial eugenol (99.00%) and β -caryophyllene (98.00%) exhibited strong contact toxicity against the summerform adults of C. chinensis with LD50 values of 0.730, 0.673, and 0.708 µg/adult, and against the nymphs with LD50 values of 1.795, 1.668, and 1.770 µg/nymph, respectively. In contrast, commercial eugenol acetate (98%) had LD50 values of 9.266 µg/adult and 9.942 µg/nymph. In a field trial, clove essential oil caused significant population reductions of 73.01% (4.80 mg/ml), 66.18% (2.40 mg/ml) and 46.56% (1.20 mg/ml), respectively. Our results demonstrated that clove essential oil and its constituents have potential as a source of natural insecticides.

WRKY transcription factors play important roles in many plant developmental processes and adaptation to the environment. However, little knowledge is available about the WRKY gene family in cultivated strawberry (Fragaria × ananassa Duch.), an important soft fruit worldwide. In this study, a total of 47 WRKY gene members were identified and renamed on the basis of their order on the chromosomes. According to their evolutionary events and conserved structure, the 47 FaWRKYs were divided into three major groups with several subgroups. A cis-element analysis showed that all FaWRKYs possessed at least one stress response-related cis-element. Comprehensive analysis, including phylogenetic analysis and expression profiling, based on real-time qPCR analysis in root, stem, leaf and fruit was performed on group III FaWRKY genes. The phylogenetic tree of the WRKY III genes in cultivated strawberry, wild Strawberry, Arabidopsis, tomato, and rice was divided into five clades. Additionally, the expression profiles of the FaWRKY genes in response to continuous cropping were further investigated based on RNA-seq data. FaWRKY25, FaWRKY32, and FaWRKY45, which are group III FaWRKY genes, were upregulated after continuous cropping. The level of reactive oxygen species (ROS) and the expression levels of PR1 and peroxidase were higher in continuous cropping (CC) than in non-continuous cropping (NCC). The results indicated that group III FaWRKYs might play an important role in continuous cropping. These results provide a foundation for genetic improvements for continuous cropping tolerance in cultivated strawberry.

During our screening program for new agrochemicals from the local wild plants and Chinese medicinal herbs, the essential oil of Cyperus rotundus rhizomes was found to possess strong insecticidal activities against the booklice, Liposcelis bostrychophila Badonnel. Essential oil of C. rotundus rhizomes was obtained by hydrodistillation and analyzed by Gas chromatography-Mass spectrometry. A total of 35 components of the essential oil of C. rotundus were identified. The main components of the essential oil were α-cyperone (29.38%), cyperene (13.97%), caryophyllene oxide (6.71%) and β-selinene (6.47%). Bioactivities-directed chromatographic separation on repeated silica gel columns led to the isolation of two compounds: cyperene and α-cyperone. α-Cyperone exhibited pronounced contact toxicity against L. bostrychophila (LC₅₀ = 41.32 μg/cm²) and was more toxic than cyperene (LC₅₀= 50.08 μg/cm²) while the essential oil acting against the booklice showed an LC₅₀ value of 102.11 μg/cm². These results suggest that the essential oil of C. rotundus rhizome and the two isolated constituent compounds may be used in grain storage to combat insect pests.