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Drought stress (DS) is one of the important abiotic stresses facing cash crops today. Drought can reduce plant growth and development, inhibit photosynthesis, and thus reduce plant yield. In this experiment, we investigated the protective mechanism of AMF on plant photosynthetic system by inoculating Paris polyphylla var. yunnanensis(P.py) with a clumping mycorrhizal fungus (AMF) under drought conditions. The drought environment was maintained by weighing AMF plants and non-AMF plants. The relative water content (RWC) of plant leaves was measured to determine its drought effect. DS decreased the RWC of plants, but AMF was able to increase the RWC of plants. chlorophyll a fluorescence curve measurements revealed that DS increased the OKJIP curve of plants, but AMF was able to reduce this trend, indicating that AMF increased the light absorption capacity of plants. DS also caused a decrease in plant Y(I) and Y(II). ETRI and ETRII, and increased Y(NO) and Y(NA) in plants, indicating that DS caused photosystem damage in plants. For the same host, different AMFs did not help to the same extent, but all AMFs were able to help plants reduce this damage and contribute to the increase of plant photosynthesis under normal water conditions.

【Objective】It is complex, time-consuming and laborious for conventional chemical detection method to detect the content of total nitrogen, potassium, total sugars, reducing sugars, total alkali, chlorine and magnesium in wrapper tobacco, while near-infrared spectroscopy technology is simple to operate and rapid to detect. The aims is to establish a near infrared spectroscopy detection model to achieve rapid quantitative analysis of the content of the seven chemical components in wrapper tobacco.【Method】Taking Yunnan cigar wrapper tobacco as the material, conventional chemical method was used to detect the content of seven chemical components in wrapper tobacco, and then near infrared spectroscopy was used to analyze the content of seven chemical components and their spectruml data of wrapper tobacco by using near infrared spectroscopy combined with partial least squares method, and the model with the optimal predictive performance was determined by comparing the root mean square error and correlation coefficient of the model.【Result】The optimal prediction results of the seven chemical components were established by the preprocessing methods of original spectrum, first derivative, first derivative, original spectrum, original spectrum, first derivative + median filtering and first derivative + median filtering, and the optimal principal component numbers were 20, 7, 4, 24, 21, 9 and 7, respectively; The training set correlation coefficients (r) of the seven models were 0.9441, 0.8589, 0.7664, 0.9511, 0.9547, 0.9031 and 0.8620, respectively. The root mean square error of cross validation (RMSECV) were 0.1288, 0.2846, 0.0280, 0.0096, 0.1894, 0.2965 and 0.0795; The correlation coefficients (r) of the validation set were 0.8958, 0.7675, 0.7181, 0.7928, 0.7282, 0.8062 and 0.7980, and the root mean square error of prediction (RMSEP) were 0.1789, 0.3011, 0.0324, 0.0193, 0.3855, 0.3990 and 0.0999. Moreover, the models were externally verified, and the results indicated that the average RSD of the predicted values and chemical values of the seven chemical components were less than 32%.【Conclusion】It was feasible to use near infrared spectroscopy to rapidly and quantitatively analyze the contents of seven chemical components in wrapper tobacco. The models had good prediction effect on the contents of seven chemical components, and could provide a reference for the rapidly and quantitatively analysis of seven chemical components in wrapper tobacco.

Tobacco black shank (TBS), caused by Phytophthora nicotianae, is one of the most harmful diseases of tobacco. There are many studies have examined the mechanism underlying the induction of disease resistance by arbuscular mycorrhizal fungi (AMF) and β-aminobutyric acid (BABA) alone, but the synergistic effects of AMF and BABA on disease resistance have not yet been studied. This study examined the synergistic effects of BABA application and AMF inoculation on the immune response to TBS in tobacco. The results showed that spraying BABA on leaves could increase the colonization rate of AMF, the disease index of tobacco infected by P.nicotianae treated with AMF and BABA was lower than that of P.nicotianae alone. The control effect of AMF and BABA on tobacco infected by P.nicotianae was higher than that of AMF or BABA and P.nicotianae alone. Joint application of AMF and BABA significantly increased the content of N, P, and K in the leaves and roots, in the joint AMF and BABA treatment than in the sole P. nicotianae treatment. The dry weight of plants treated with AMF and BABA was 22.3% higher than that treated with P.nicotianae alone. In comparison to P. nicotianae alone, the combination treatment with AMF and BABA had increased Pn, Gs, Tr, and root activity, while P. nicotianae alone had reduced Ci, H2O2 content, and MDA levels. SOD, POD, CAT, APX, and Ph activity and expression levels were increased under the combined treatment of AMF and BABA than in P.nicotianae alone. In comparison to the treatment of P.nicotianae alone, the combined use of AMF and BABA increased the accumulation of GSH, proline, total phenols, and flavonoids. Therefore, the joint application of AMF and BABA can enhance the TBS resistance of tobacco plants to a greater degree than the application of either AMF or BABA alone. In summary, the application of defense-related amino acids, combined with inoculation with AMF, significantly promoted immune responses in tobacco. Our findings provide new insights that will aid the development and use of green disease control agents.

Orcinol glucoside (OG), mainly found in the rhizome of the traditional Chinese herb Curculigo orchioides Gaertn, is noted for its antidepressant effects. In this study, an efficient screening pipeline was established for identifying the highly active orcinol synthase (ORS) and UDP-dependent glycosyltransferase (UGT) involved in the biosynthesis of OG by combining transcriptome analysis, structure-based virtual screening, and in vitro enzyme activity assays. By enhancing the downstream pathway, metabolic engineering and fermentation optimization, the OG production in Yarrowia lipolytica was improved 100-fold, resulting in a final yield of 43.46 g/L (0.84 g/g DCW), which is almost 6,400-fold higher than the extraction yield from C. orchioides roots. This study provides a reference for rapid identification of functional genes and high-yield production of natural products.

Pairs polyphylla var. yunnanensis is a perennial herb, and its rhizomes are used as medicine to invigorate blood circulation, dissipate blood stasis, relieve swelling and pain, clear heat and detoxify the body. However, due to its slow growth, most of the saponin content is low, while the content of saponins is higher in Paris fargesii Franch of the same genus. The isolation and screening of strains from P. fargesii Franch that promote the accumulation of saponin content in P. polyphylla var. yunnanensis is important to improve the growth rate of artificially cultivated P. polyphylla var. yunnanensis and increase its medicinal activity. Plant symbiotic strains are biologically active microorganisms that can promote the growth and development of host plants through direct probiotic effects and indirect disease resistance mechanisms. Here, we isolated four strains of symbiotes, including two bacteria, Bacillus cereus (LgD2) and Bacillus thuringiensis (LgD10), and two fungi, Aspergillus tamari (TPD11) and Fusarium oxysporum (TPB). All of them promoted the biomass, chlorophyll content and photosynthetic efficiency of P. polyphylla var. yunnanensis seedlings to different degrees and effectively stimulated the accumulation of saponin content in P. polyphylla var. yunnanensis seedlings to improve the expression of saponin synthesis pathway genes. The symbiotes also promoted the enzymatic activities of the enzymes superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO) and phenylalanine aminolase (PAL), improved the physiological indicators of tobacco plants (plant height, crown width, leaf length and leaf width), reduced the incidence of tobacco black shank, and improved the growth and resistance-related genes of tobacco. In conclusion, the four symbiotic strains TPD11, TPB, LgD10 and LgD2 play an important role in regulating the growth, promoting saponin accumulation, and disease resistance of P. polyphylla var. yunnanensis.

Tobacco black shank (TBS), caused by Phytophthora nicotianae, is one of the most harmful diseases of tobacco. There are many studies have examined the mechanism underlying the induction of disease resistance by arbuscular mycorrhizal fungi (AMF) and Ɓ-aminobutyric acid (BABA) alone, but the synergistic effects of AMF and BABA on disease resistance have not yet been studied. This study examined the synergistic effects of BABA application and AMF inoculation on the immune response to TBS in tobacco. The results showed that spraying BABA on leaves could increase the colonization rate of AMF, the disease index of tobacco infected by P.nicotianae treated with AMF and BABA was lower than that of P.nicotianae alone. The control effect of AMF and BABA on tobacco infected by P.nicotianae was higher than that of AMF or BABA and P.nicotianae alone. Joint application of AMF and BABA significantly increased the content of N, P, and K in the leaves and roots, in the joint AMF and BABA treatment than in the sole P. nicotianae treatment. The dry weight of plants treated with AMF and BABA was 22.3% higher than that treated with P.nicotianae alone. In comparison to P. nicotianae alone, the combination treatment with AMF and BABA had increased Pn, Gs, Tr, and root activity, while P. nicotianae alone had reduced Ci, H2O2 content, and MDA levels. SOD, POD, CAT, APX, and Ph activity and expression levels were increased under the combined treatment of AMF and BABA than in P.nicotianae alone. In comparison to the treatment of P.nicotianae alone, the combined use of AMF and BABA increased the accumulation of GSH, proline, total phenols, and flavonoids. Therefore, the joint application of AMF and BABA can enhance the TBS resistance of tobacco plants to a greater degree than the application of either AMF or BABA alone. In summary, the application of defense-related amino acids, combined with inoculation with AMF, significantly promoted immune responses in tobacco. Our findings provide new insights that will aid the development and use of green disease control agents. [ABSTRACT FROM AUTHOR]

Intercropping is a widespread cropping system to increase land productivity and decreases soil erosion. However, considering economic benefits of intercropping mountain agriculture is deficient. A field experiment was conducted to determine productivity, economic efficiency, and soil conservation benefits of intercropping of maize (Zea mays L.) with chili (Capsicum annuum L.) and setaria grass (Setaria anceps Stapf ex Massesy) in Yunnan. Runoff, sediment, crop yield, and economic benefits were evaluated under sole maize (SM), sole chili (SC), maize/chili intercropping (MCI), and maize/setaria grass intercropping (MGI). The results suggested that intercropping decreased runoff when compared with sole crop. The MGI had the least sediment, followed by MCI, SM, and SC. Severe soil loss was observed in sole crop systems but not in intercropping systems. Moreover, the land equivalent ratio (LER) of MCI ranged from 1.22 to 1.69, and mean economic income (US$3955 ha−1) were 29.91, 16.38, and 23.41% higher than that of SM, SC, and MGI, respectively. Therefore, MCI can integrate the benefits of productivity, economy, and soil conservation, suggesting that intercropping of maize and chili, a staple-cash crop pattern, should be favored in mountain agriculture. [ABSTRACT FROM AUTHOR]