Culture storage age and fungal re‐isolation from host‐tissue influence Colletotrichum spp. virulence to pepper fruits

Using resistant cultivars is the most sustainable and practical approach against plant diseases. Plant germplasm and breeding lines are selected and assayed against, usually, the most aggressive or virulent strains of a pathogen (e.g., fungus) that causes the disease. However, prolong storage of the pathogen in culture media could affect virulence that, consequently, also influence the outcome of the resistance assay. This study demonstrates that long‐term storage (at least a year) of Colletotrichum truncatum and C. scovillei, causal agents of pepper anthracnose, in potato dextrose agar (PDA) medium decreased the aggressiveness and virulence of the fungus in host‐pepper fruits. However, reintroduction of the pathogen to the host and isolation of the pathogen as the new inoculum, prior to inoculation assays, increased the virulence of the fungi. These findings suggest that re‐inoculation and re‐isolation of Colletotichum truncatum and C. scovillei that have been stored for at least 1 year in PDA medium are necessary when using fungal cultures in pathogenicity and plant resistance assays to achieve desirable, comparable and reliable results.     

生防菌株1404的鉴定及其对采后柑橘炭疽病的防治效果

【目的】柑橘是世界上重要的果树。由胶孢炭疽菌[Colletotrichum gloeosporioides(Penz.)Sacc.]引起的柑橘炭疽病是柑橘生产的主要病害。为开发对采后柑橘炭疽病有效的生防措施,对从辣椒根际土壤中分离的一株生防细菌1404进行了鉴定,并对其特性及生防效果进行了研究。【方法】根据菌株1404的形态特征、生理生化特性以及16SrDNA序列对其进行鉴定;通过连续在人工培养基上转代培养,测定该菌株拮抗活性的稳定性;用果实刺伤接种法对采后柑橘炭疽病的防效进行测定。【结果】菌株1404与来自GenBank的短短芽孢杆菌[Brevibacillus brevis(Migula)Shidaetal.]以100%bootstrap水平类聚一群。该菌株的形态特征及生理生化特性与Brevibacillus brevis相符。连续4次在人工培养基上转代培养,菌株1404对柑橘炭疽病菌生长的抑制力没有发生明显改变。该生防菌对柑橘炭疽病的防治效果明显,处理后第20天防效达到64.9%。【结论】根据16SrDNA序列、形态特征、生理生化特性,将菌株1404鉴定为短短芽孢杆菌。本文首次报道对柑橘采后炭疽病具有较好防效的生防菌Brevibacillus brevis。     

珍珠李炭疽菌对三种杀菌剂的敏感性测定

由胶孢炭疽菌复合种(Colletotrichum gloeosporioides species complex)引起的炭疽病是珍珠李(Prunus salicina Lind1)产业生产上的主要病害，为明确珍珠李炭疽菌对吡唑醚菌酯、苯醚甲环唑和咪鲜胺的敏感性，比较不同地理来源及不同种炭疽菌对三种药剂敏感性差异。采用菌丝生长速率法分别测定三种杀菌剂对采自不同地区26株珍珠李炭疽菌的药剂敏感性。结果表明，供试的26株珍珠李炭疽菌对咪鲜胺的敏感性最高，EC₅₀值介于0.010 8～0.645 2μg/mL之间，平均值为(0.191 2±0.03)μg/mL;苯醚甲环唑次之，EC₅₀值介于0.165 8～2.168 0μg/mL之间，平均值为(0.725 8±0.088 0)μg/mL;吡唑醚菌酯最低，EC₅₀值介于0.058 3～84.566 0μg/mL之间，平均值为(6.276 3±3.525 5)μg/mL。供试的26株珍珠李炭疽菌整体对以上三种杀菌剂敏感，且对咪鲜胺的敏感性最高，苯醚甲环唑次之，对吡唑醚菌酯的敏感性最...     

红肉小果型番木瓜品种'美中红'体胚的诱导

用红肉小果型番木瓜品种‘美中红’为外植体,探讨不同成熟度的幼胚、不同浓度2,4-D和培养条件对其体胚的诱导以及体胚形成过程的结果表明:以子叶和内外种皮都为白色且个体较大的番木瓜幼胚(90~120d)在含10mg·L-12,4-D的培养基中和黑暗条件下诱导愈伤组织的效果最佳,愈伤组织的诱导率随着2,4-D浓度的增加而增加。番木瓜愈伤组织最先发生于形态学上的胚根下端,体胚多发生于形态学上的胚芽上端。     

假单胞菌T1-3-2的抑菌特性及其对杉木的抗病促生作用

【背景】生物防治是“基于自然的解决方案”,有利于生态文明和可持续发展,开展生物防治技术研究的基础是明确菌株的生防作用和抑菌特性。【目的】探究杉木内生菌株T1-3-2的抑菌促生特性,为研制该菌株生防菌剂、防治杉木炭疽病(Cunninghamia lanceolata anthracnose)奠定基础。【方法】通过形态学特征、生理生化特性及16S rRNA基因序列分析,确定菌株T1-3-2的分类地位;通过平板对峙、菌落径向生长抑制率和平板倒扣等方法测定细菌及其挥发性气体和次级代谢产物的抑菌作用;同时,测定其促生作用和室内防效。【结果】菌株T1-3-2与桉生假单胞菌(Pseudomonas eucalypticola)亲缘性较近,属于假单胞菌属。该菌株对分属于6个属的10株靶标菌株具有较强的拮抗作用,尤其对炭疽菌属、拟盘多毛孢属、黑孢霉属和葡萄座腔菌属的6株靶标菌株抑制率高达80%以上。室内盆栽试验显示：菌株T1-3-2用Kings Medium B液体培养基的发酵菌液对杉木炭疽病的防效可达74.20%,同时能有效改善杉木幼苗的生长状况、增加生物量。【结论】菌株T1-3-2隶属于假单胞菌属,对杉木具有良好的抗病促生作用,是一株具有开发潜力的生防菌株。     

Altering lipase activity and enantioselectivity in organic media using organo-soluble bases: Implication for rate-limiting proton transfer in acylation step

With the hydrolytic resolution of (R,S)-naproxen 2,2,2-trifluoroethyl esters via a partially purified papaya lipase (PCPL) in water-saturated isooctane as the model system, the enzyme activity, and enantioselectivty is altered by adding a variety of organo-soluble bases that act as either enzyme activators (i.e., TEA, MP, TOA, DPA, PY, and DMA) or enzyme inhibitors (i.e., PDP, DMAP, and PP). Triethylamine (TEA) is selected as the best enzyme activator as 2.24-fold increase of the initial rate for the (S)-ester is obtained when adding 120 mM of the base. By using an expanded Michaelis-Menten mechanism for the acylation step, the kinetic analysis indicates that the proton transfer for the breakdown of tetrahedral intermediates to acyl-enzyme intermediates is the rate-limiting step, or more sensitive than that for the formation of tetrahedral intermediates when the enzyme activators of different pKa are added. However, no correlation for the proton transfers in the acylation step is found when adding the bases acting as enzyme deactivators.     

烟草炭疽病拮抗生防菌的筛选

本文应用荧光假单胞杆菌的16S-23S ribosomal RNA序列以及部分抗菌素合成基因序列的PCR鉴定引物,对从烟草根际分离到的400份细菌进行了鉴定,结果获得了21份含Prn(硝吡咯菌素)合成酶基因的荧光假单胞杆菌和1份含有DAPG(2,4-二乙酰基藤黄酚)合成酶基因以及PCA(Phenazine-1-carboxylic acid,吩嗪-1-羧酸)的荧光假单胞杆菌.室内实验结果表日月,含DAPG和PCA的荧光假单胞杆菌对烟草炭疽病具有明显拮抗作用.