CRISPR/Cas9-Mediated SlMYBS2 Mutagenesis Reduces Tomato Resistance to Phytophthora infestans

Phytophthora infestans (P. infestans) recently caused epidemics of tomato late blight. Our study aimed to identify the function of the SlMYBS2 gene in response to tomato late blight. To further investigate the function of SlMYBS2 in tomato resistance to P. infestans, we studied the effects of SlMYBS2 gene knock out. The SlMYBS2 gene was knocked out by CRISPR-Cas9, and the resulting plants (SlMYBS2 gene knockout, slmybs2-c) showed reduced resistance to P. infestans, accompanied by increases in the number of necrotic cells, lesion sizes, and disease index. Furthermore, after P. infestans infection, the expression levels of pathogenesis-related (PR) genes in slmybs2-c plants were significantly lower than those in wild-type (AC) plants, while the number of necrotic cells and the accumulation of reactive oxygen species (ROS) were higher than those in wild-type plants. Taken together, these results indicate that SlMYBS2 acts as a positive regulator of tomato resistance to P. infestans infection by regulating the ROS level and the expression level of PR genes.     

石林人参果的品质差异及综合性评价

目的 探究不同海拔、不同种植方式、不同栽培方式和不同土壤类型下石林人参果的品质差异,并对其进行综合性评价。方法 本研究以石林县不同海拔基地种植的人参果为材料,通过营养成分分析,采用熵权-逼近理想解排序(technique for order preference by similarity to ideal solution, TOPSIS)法,以靠近正理想解和远离负理想解为基准,同时对人参果多个品质指标进行全面比较评价。结果 通过相关性分析得出,可溶性固形物含量与果实中Mn间存在显著正相关,与果实中S、Fe、K间存在显著负相关,与土壤中有机C、Ca、Cu、Fe间存在显著正相关,与土壤中δ¹³C、K、Na间存在显著负相关。还原糖含量与果实中总N间存在显著负相关,与土壤中δ¹⁵N间存在显著正相关,与土壤中K、Na间存在显著负相关。维生素C (vitamin C, VC)含量与果实中有机C、Ca、Fe、Mg、Mn、Na间存在显著负相关,与土壤中Mg、Mn间存在显著负相关。可滴定酸与果实中S、Cu间存在显著正相关,与果实中Mn间存在显著负相关,与土...     

Polyamine Oxidase Triggers H2O2-Mediated Spermidine Improved Oxidative Stress Tolerance of Tomato Seedlings Subjected to Saline-Alkaline Stress

Saline-alkaline stress is one of several major abiotic stresses in crop production. Exogenous spermidine (Spd) can effectively increase tomato saline-alkaline stress resistance by relieving membrane lipid peroxidation damage. However, the mechanism through which exogenous Spd pre-treatment triggers the tomato antioxidant system to resist saline-alkaline stress remains unclear. Whether H₂O₂ and polyamine oxidase (PAO) are involved in Spd-induced tomato saline-alkaline stress tolerance needs to be determined. Here, we investigated the role of PAO and H₂O₂ in exogenous Spd-induced tolerance of tomato to saline-alkaline stress. Results showed that Spd application increased the expression and activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), and the ratio of reduced ascorbate (AsA) and glutathione (GSH) contents under saline-alkaline stress condition. Exogenous Spd treatment triggered endogenous H₂O₂ levels, SlPAO4 gene expression, as well as PAO activity under normal conditions. Inhibiting endogenous PAO activity by 1,8-diaminooctane (1,8-DO, an inhibitor of polyamine oxidase) significantly reduced H₂O₂ levels in the later stage. Moreover, inhibiting endogenous PAO or silencing the SlPAO4 gene increased the peroxidation damage of tomato leaves under saline-alkaline stress. These findings indicated that exogenous Spd treatment stimulated SlPAO4 gene expression and increased PAO activity, which mediated the elevation of H₂O₂ level under normal conditions. Consequently, the downstream antioxidant system was activated to eliminate excessive ROS accumulation and relieve membrane lipid peroxidation damage and growth inhibition under saline-alkaline stress. In conclusion, PAO triggered H₂O₂-mediated Spd-induced increase in the tolerance of tomato to saline-alkaline stress.     

黄果茄果实杀螺成分的分离和结构解析

黄果茄在长江中下游血吸虫病疫区分布广泛。从黄果茄果实中提取分离出一种新的具有灭螺活性的化合物,相对分子质量是772,分子式为C39H64O11N;通过化学和光谱方法解析了结构,含澳洲茄碱的骨架。该化合物浸杀钉螺成螺实验结果表明,在质量浓度达到0.5800mg/L,浸杀48h,钉螺致死率达到100%。     

Purification and some properties of polyphenoloxidase in eggplant (Solanum melongena)

Polyphenoloxidase (EC 1.10.3.1) in eggplant (Solatium melongena L) was purified by ammonium sulphate fractionation, DEAE-Cellulofine and DEAE-Toyopearl chromatography and Sephadex G-100 gel filtration. The enzyme was purified about 110-fold with a recovery of 5%. The purified enzyme more quickly oxidised chlorogenic acid (5-caffeoylquinic acid, IUPAC) than 10 other substrates used. The K_m value for the enzyme was found to be 0·50 mM with respect to chlorogenic acid; the optimum pH of the enzyme was about 4 with enzyme stability between pH 5 and 8. The enzyme was completely inactivated after heat treatment at 75°C for 30 min or 80°C for 5 min. Sodium metabisulphite, potassium cyanide and sodium fluoride markedly inhibited the enzyme activity.     

Variation in nutrient composition of Australian retail potatoes over a 12-month period

‘Pontiac’, ‘Sebago’ and potatoes marketed under the general name of New potatoes were purchased from retail outlets in Sydney, Australia every 2 weeks over a 12-month period during 1982–83 to determine the change in composition over a season. Data are presented for water, vitamin C, starch, sugars (fructose, glucose and sucrose), dietary fibre, protein, fat, organic acids (malic, citric and oxalic acids), ash, carotenes, thiamin, riboflavin, niacin, potassium, sodium, calcium, magnesium, iron and zinc levels, edible weight and energy content. The level of vitamin C varied throughout the year from 10 to 23 mg 100 g^?1 for ‘Pontiac’, 14 to 29 mg 100 g^?1 for ‘Sebago’ and 16 to 32 mg 100 g^?1 for New potatoes with the lowest values occurring in August to September (late winter to early spring) and the highest values in December to January (mid summer). Substantial variations also occurred in the water content, which was higher, and the level of starch and hence energy content, which was lower, during the cooler months of the year. Smaller changes were noted for niacin and thiamin which were lower and sugars which were higher during the winter period.