天然植物生长调节剂芸苔素的生物活性及应用浅析

天然芸苔素属于甾体类植物内源生物活性物质,其骨架为甾醇,其中芸苔素内酯生物活性最强,被称为第六类植物激素,是高效、广谱、无毒的植物生长调节剂(PGR)。为更好地将芸苔素推广应用于农业生产,本文概括了芸苔素内酯的生物活性及在粮食、果蔬等作物上的应用。探讨了芸苔素内酯在提高种子活力,促进作物生长,大幅度促进产量提升以及品质改善,提升作物抗逆性,缓解农药对作物影响的研究概况及取得的进展,指出了芸苔素内酯的应用是作物增产增收的关键途径,同时,能够减少化肥、农药的施用量,减少作物种植成本与减轻环境污染,将带来显著的经济效益。     

Dietary choline improves growth performance,antioxidant ability and reduces lipid metabolites in practical diet for juvenile Pacific white shrimp,Litopenaeus vannamei

An 8‐week feeding trial was conducted to evaluate the effects of dietary choline levels on growth performance, antioxidant capacity and lipid metabolites in juvenile Pacific white shrimp. Six isonitrogenous and isolipidic diets were formulated to supply 0, 1,000, 2,000, 4,000, 6,000, 10,000 mg/kg choline chloride, and dietary choline levels were analysed to be 1,317 (basal diet), 1,721, 2,336, 3,294, 5,421 and 9,495 mg/kg, respectively. Dietary choline levels significantly influenced percent weight gain (PWG) and protein efficiency ratio (PER), with the highest PWG was observed in shrimp fed the 5,421 mg/kg choline diet. However, there were no significant differences in proximate composition of whole body and muscle. Shrimp fed the diet containing 2,336 mg/kg choline had lower HDL and LDL in haemolymph than those fed the basal diet (1,317 mg/kg diet). Dietary choline prevented the accumulation of free radicals and improved antioxidant capacity by increasing catalase activity and reducing malondialdehyde content. Based on broken‐line regression and quadratic regression analysis between PWG against dietary choline levels, the optimal choline requirements were estimated to be 3,254.1 and 6,488.3 mg/kg for juvenile L. vannamei, respectively.     

Bacteria and antibiotic resistance detection in fractures of wild birds from wildlife rehabilitation centres in Spain

Anatomic adaptations make birds more prone to open fractures with exposed bone parts losing vascularization. As a result of this exposure, fractures are colonized by different microorganisms, including different types of bacteria, both aerobic and anaerobic, causing osteomyelitis in many cases. For this reason, antibiotic treatment is common. However, carrying out antibiotic treatment without carrying out a previous antibiogram may contribute to increased resistance against antibiotics, especially in migratory wild birds. In this paper, bacterial counts regarding fracture type, bacterial identification and antibiotic resistance have been analysed in wild birds from wildlife rehabilitation centres in Spain. The results obtained showed that open fractures had higher bacterial counts (CFU/mL) than closed ones. Bacteria in family Enterobacteriaceae, identified were Escherichia spp., Enterobacter spp., Shigella spp., Hafnia alvei, Proteus mirabilis, Leclercia adecarboxylata and Pantoea agglomerans. Other bacteria present in wild birds’ fractures were Aeromonas spp., Enterococcus spp. Bacillus wiedmannii and Staphylococcus sciuri. All species found presented resistance to at least one of the antibiotics used. Wild birds can be implicated in the introduction, maintenance and global spreading of antibiotic resistant bacteria and represent an emerging public health concern. Results obtained in this paper support the idea that it is necessary to take this fact into account before antibiotic administration to wild animals, since it could increase the number of bacteria resistant to antibiotics.     

不同根瘤菌菌株对盐胁迫下甘农9号苜蓿生长及生理特性的影响

以已筛选的与甘农9号苜蓿匹配效果较好的5株根瘤菌株为研究对象,研究不同浓度NaCl(0、0.4%、0.8%、1.2%)胁迫下,不同根瘤菌株对甘农9号苜蓿生长及生理特性的影响。研究结果表明,在非接菌情况下,随NaCl浓度提高,对苜蓿的生长抑制作用增大,而接菌以后,不同菌株均通过其固氮作用、根瘤菌与苜蓿共生对其生长及生理应答特性的改变来提高苜蓿抗盐胁迫的能力。但是不同菌株与苜蓿匹配对盐的耐受程度不一。经隶属函数综合分析表明,非盐胁迫下,接菌后,对苜蓿生长及生理特性影响较明显的菌株是Da99、DL58及QL31B,而菌株Ga66、Wa32与对照比较差异不显著;在不同盐胁迫处理下,所有菌株相比对照都明显促进苜蓿的生长及提高其抗盐性。在0.4%盐浓度下与甘农9号苜蓿匹配效应最好的菌种是Ga66、QL31B,其隶属函数值较对照分别提高了53.8%和58.6%;在0.8%盐浓度下所有参试菌株均与甘农9号苜蓿匹配效应较好;在1.2%盐浓度下与甘农9号苜蓿匹配效应最好的菌种是Ga66、QL31B;在任何盐浓度下与甘农9号苜蓿匹配效应均好的菌种是QL31B。     

Characterization of field‐evolved resistance to Bacillus thuringiensis‐derived Cry1F δ‐endotoxin in Spodoptera frugiperda populations from Argentina

BACKGROUND

Transgenic maize (Zea mays L.) event TC1507 (Herculex^® I insect protection), expressing Cry1F δ‐endotoxin derived from Bacillus thuringiensis var. aizawai, was commercialized in 2003 in the Americas. Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) susceptibility to Cry1F was monitored annually across several regions in Argentina using diagnostic concentration bioassays. Reduced performance of TC1507 maize against S. frugiperda was reported in 2013. A resistant population was established in the laboratory and the dominance of Cry1F resistance was characterized.

RESULTS

During 2012–2015, high‐survivorship of several populations was observed in the resistance monitoring program. Reciprocal crosses of a Cry1F‐resistant population with a Cry1F‐susceptible population were evaluated to calculate effective dominance (D_ML) based on mortality levels observed at 100 µg/ml Cry1F. Two additional dominance levels (D_LC and D_EC) were calculated using lethal (LC₅₀) or effective concentration (EC₅₀) derived from concentration–response bioassays. Estimates indicated that Cry1F resistance in S. frugiperda in Argentina was either highly recessive (D_ML = 0.005) or incompletely recessive (D_LC < 0.26 and D_EC < 0.19).

CONCLUSION

This study is the first documented confirmation and characterization of S. frugiperda Cry1F field‐evolved resistance in Argentina. The resistance to Cry1F in S. frugiperda populations collected in Argentina, is autosomal and incompletely recessive similar to the resistance reported in Brazil. © 2017 The Authors. Pest Management Science published by John Wiley © Sons Ltd on behalf of Society of Chemical Industry.     

花铃期干旱胁迫对不同棉花品种光合特性影响及抗旱性评价

以28份抗旱性不同的棉花品种为材料,通过大田花铃期水分胁迫,以抗旱系数和主成分分析综合评价各个棉花品种的抗旱水平,并对其评价和等级进行划分。结果表明,各个棉花品种在花铃期干旱胁迫下,各指标反应程度不同,其中叶绿素、净光合速率、水蒸汽压亏缺、气孔导度变化较明显,通过RI值聚类分析,将材料分成4个大类,第Ⅰ类为高抗型品种有C1470、ND359-5、新炮1号、新陆中39等18份品种;第Ⅱ类为中抗型的包括天合995、吉扎81、大铃棉、TM-1、10615-1、塔什干7号;第Ⅲ类为敏感型的包括新陆早1号、新石K7、鲁棉28;第Ⅳ为极敏感型的新陆早26。进一步利用逐步回归建立回归方程D=-1.496+0.775Ci+0.160Gs-0.020VPD+0.719Pn+0.799Tr-0.241WUE+0.663Chl(R2=0.996),筛选出7个指标,分别为Ci、Gs、VPD、A、Tr、WUE、Chl,各材料估计精度大于97.55%。     

夏玉米蒸散优化参数模型及参数敏感性分析

分别采用2种不同的冠层阻力模型和土壤阻力模型,组合成4种Shuttleworth-Wallace(S-W)模型,模拟夏玉米农田灌浆期的逐时蒸散量,以涡度相关法观测蒸散量为实测值检验模型改进的效果,找出最优冠层阻力模型和土壤阻力模型,并分析最优S-W模型对各阻力参数的敏感性。结果表明:李俊改进型有效叶面积指数冠层阻力模型和Sellers土壤阻力模型组合的S-W模型模拟效果最好,S-W模型估算玉米田蒸散的精度显著提高,蒸散发模拟值与实测值的相关系数、一致性指数更接近1,蒸散发模拟的相对误差和均方根误差变小。敏感性分析表明,在计算各个阻力参数模型中,S-W1模型估算蒸散发对冠层阻力最敏感,其次是土壤阻力和有效叶面积指数;采用改进型有效叶面积指数冠层阻力模型和Sellers土壤阻力参数模型组合后,在一定程度上提高了模型精度,提高了计算准确率。