Heterologous expression of taxane genes confers resistance to fall armyworm in Nicotiana benthamiana.

KEY MESSAGE: Taxadiene synthase, taxadiene-5α-hydroxylase, and taxane 13α-hydroxylase genes were introduced into Nicotiana benthamiana, and the improved resistance to lepidoptera pest fall armyworm was reported. Fall armyworm (FAW) is a serious agricultural pest. Genetic engineering techniques have been used to create pest-resistant plant varieties for reducing pest damage. Paclitaxel is a diterpenoid natural metabolite with antineoplastic effects in medicine. However, the effects of taxanes on the growth and development of lepidoptera pests, such as the FAW, are unknown. Here, selected paclitaxel precursor biosynthesis pathway genes, taxadiene synthase, taxane 5α-hydroxylase, and taxane 13α-hydroxylase, were engineered in the heterologous host Nicotiana benthamiana plants. Bioassay experiments showed that the transgenic N. benthamiana plants displayed improved resistance to FAW infestation, with degeneration of gut tissues and induced expression of apoptosis-related genes. Cytotoxicity experiment showed that the paclitaxel precursor, 10-deacetylbaccatin III, is cytotoxic to Sf9 cells, causing cell cycle arrest at the G2/M phase and disorder of the cytoskeleton. Metabolome analysis showed that heterologous expression of taxane genes in N. benthamiana affected the digestive system, steroid hormone and purine metabolism pathways of FAW larvae. In summary, this study provides a candidate approach for FAW control.

GhMYC2 activates cytochrome P450 gene CYP71BE79 to regulate gossypol biosynthesis in cotton.

MAIN CONCLUSION: GhMYC2 regulates the gossypol biosynthesis pathway in cotton through activation of the expression of gossypol synthesis gene CYP71BE79, CDNC, CYP706B1, DH1, and CYP82D113. Cotton is one of the main cash crops globally. Cottonseed contains fiber, fat, protein, and starch, and has important economic value. However, gossypol in cottonseed seriously affects the development and utilization of cottonseed. Nonetheless, gossypol has great application potential in agriculture, medicine, and industry. Therefore, it is very important to study gossypol biosynthesis and its upstream regulatory pathways. It has been reported that the content of gossypol in hairy roots of cotton is regulated through jasmonic acid signaling; however, the specific molecular mechanism has not been revealed yet. We found that the expression of basic helix-loop-helix family transcription factor GhMYC2 was significantly upregulated after exogenous administration of methyl jasmonate to cotton seedlings, and the content of gossypol changed significantly with the variation of GhMYC2 expression. Further studies revealed that GhMYC2 could specifically bind to the G-Box in the promoter region of CDNC, CYP706B1, DH1, CYP82D113, CYP71BE79 to activate its expression and regulate gossypol synthesis, and its activation of CYP71BE79 promoter was inhibited by GhJAZ2. Not only that GhMYC2 could also interact with GoPGF. In this work, the molecular mechanisms of gossypol biosynthesis regulated by GhMYC2 were analyzed. The results provide a theoretical basis for cultivating new varieties of low-gossypol or high-gossypol cotton and creating excellent germplasm resources.

A Case Report of Gemella haemolysans Keratitis After Refractive Surgery.

PURPOSE: Systematic review of Gemella haemolysans infection associated with ophthalmology, and to summarize the clinical characteristics of Gemella haemolysan s keratitis after refractive surgery. METHODS: Case report and literature review. RESULTS: We report an 18-year-old man who developed corneal infection after Trans-PRK, and the culture results of lesion specimens confirmed G. haemolysans keratitis. He was treated with fortified topical antibiotics, and clinical improvement was noted shortly after treatment. Resolution of keratitis was achieved at 1 month. Then, a systematic review of the reported cases of ocular G. haemolysans infection was conducted. We summarized clinical manifestations of G. haemolysans infection in cornea. CONCLUSION: We reported a case of G. haemolysans keratitis infection after refractive surgery, and reviewed the literature of ocular G. haemolysans infection.

Identification and Comprehensive Structural and Functional Analyses of the EXO70 Gene Family in Cotton.

The EXO70 gene is a vital component of the exocytosis complex and participates in biological processes ranging from plant cell division to polar growth. There are many EXO70 genes in plants and their functions are extensive, but little is known about the EXO70 gene family in cotton. Here, we analyzed four cotton sequence databases, identified 165 EXO70 genes, and divided them into eight subgroups (EXO70A-EXO70H) based on their phylogenetic relationships. EXO70A had the most exons (≥11), whereas the other seven each had only one or two exons. Hence, EXO70A may have many important functions. The 84 EXO70 genes in Asian and upland cotton were expressed in the roots, stems, leaves, flowers, fibers, and/or ovules. Full-length GhEXO70A1-A cDNA was homologously cloned from upland cotton (Gossypium hirsutum, G. hirsutum). Subcellular analysis revealed that GhEXO70A1-A protein was localized to the plasma membrane. A yeast two-hybrid assay revealed that GhEXO70A1-A interacted with GhEXO84A, GhEXO84B, and GhEXO84C. GhEXO70A1-A silencing significantly altered over 4000 genes and changed several signaling pathways related to metabolism. Thus, the EXO70 gene plays critical roles in the physiological functions of cotton.

BIN2 negatively regulates plant defence against Verticillium dahliae in Arabidopsis and cotton.

Verticillium wilt is caused by the soil-borne vascular pathogen Verticillium dahliae, and affects a wide range of economically important crops, including upland cotton (Gossypium hirsutum). Previous studies showed that expression levels of BIN2 were significantly down-regulated during infestation with V. dahliae. However, the underlying molecular mechanism of BIN2 in plant regulation against V. dahliae remains enigmatic. Here, we characterized a protein kinase GhBIN2 from Gossypium hirsutum, and identified GhBIN2 as a negative regulator of resistance to V. dahliae. The Verticillium wilt resistance of Arabidopsis and cotton were significantly enhanced when BIN2 was knocked down. Constitutive expression of BIN2 attenuated plant resistance to V. dahliae. We found that BIN2 regulated plant endogenous JA content and influenced the expression of JA-responsive marker genes. Further analysis revealed that BIN2 interacted with and phosphorylated JAZ family proteins, key repressors of the JA signalling pathway in both Arabidopsis and cotton. Spectrometric analysis and site-directed mutagenesis showed that BIN2 phosphorylated AtJAZ1 at T196, resulting in the degradation of JAZ proteins. Collectively, these results show that BIN2 interacts with JAZ proteins and plays a negative role in plant resistance to V. dahliae. Thus, BIN2 may be a potential target gene for genetic engineering against Verticillium wilt in crops.