水稻白叶枯病菌及其毒素引起烟草叶片组织坏死机制的研究

 水稻白叶枯病菌JXO Ⅲ细胞悬浮液及其分泌的毒素溶液接种到烟草叶片中,都能在烟草叶片上产生快速的坏死反应。引起坏死反应所需的最短时间分别为接种后8 h和0.5 h。低浓度的JXOⅢ(< 107 cfu/ml)接种后36~48 h内形成褪绿斑,而低浓度的毒素(< 2.5 mg/ml)接种后随时间延长在接点无任何可见变化。依文斯蓝(Evans blue)染色发现,毒素和JXOⅢ分别在接种后0.5 h和6 h内细胞大量死亡。叶圆片法测定表明,接种毒素后2 h内烟草细胞膜透性迅速上升,接种JXOⅢ后9 h细胞膜透性开始明显上升。毒素处理的烟草叶片中LOX、POX、SOD、CAT活性水平较对照降低,而JXOⅢ处理中上述酶活性较对照有不同程度的增加。蛋白质合成抑制剂环己酰亚胺,RNA合成抑制剂放线菌素D和钙离子通道阻断剂氯化镧分别以7.1×10^-5 M、1×10^-4 M和1×10^-3 M浓度有效地抑制JXOⅢ在烟草上形成坏死反应,这些抑制剂对毒素在烟草上的坏死反应则没有影响。     

水稻黄单胞菌水稻变种的rpfA基因的定位和次级克隆

水稻黄单胞菌水稻变种产生两种顺乌头酸酶（ＸｏｏＡｃａｎＡ和ＸｏｏＡｃａｎＢ）,编码ＸｏｏｃａｎＡ的ｒｐｆＡ基因已被克隆在重组质粒ｐＧＸＮ３０００中。本工作通过转座子Ｔｎ５Ｂ２０诱变ｐＧＸＮ３０００,鉴定了ｒｐｆＡ基因的位置及其转录方向,并进一步将含有完整ｒｐｆＡ基因的４．８ｋｂＡｓｐ７１８ＥｃｏＲⅠ片段次级克隆到了多用途载体质粒ｐＩＪ３２００。     

生物及非生物诱导因子对水稻白叶枯病的诱导抗性及其与活性氧代谢的关系

 以对白叶枯病高抗的水稻品种余水糯和高感的水稻品种浙辐802为材料,于2叶期用Tiron、Paraquat(PQ)和稻白叶枯病菌弱毒株75-1进行诱导处理,测定诱导处理后3、24、48、72 h叶中超氧化物歧化酶(SOD)活性、O2-产生速率及丙二醛(MDA)含量的动态变化,并于3叶期用白叶枯病菌强毒株76-25进行挑战接种,结果表明：75-1和PQ均诱导两品种产生了系统抗性,并使诱导叶中O2-产生速率和MDA含量增加。75-1使O2-产生速率在24 h达峰值,比对照升高30.6%(余水糯)和25.3％(浙辐802);而PQ使O2-产生速率在24～72 h维持较高水平,比对照升高49.4％(余水糯) 和39.7％(浙辐802)。MDA含量的变化晚于O2-产生速率的改变,在72 h达最高值。75-1使SOD活性降低,并在24 h达最大降幅;而PQ使SOD活性升高,并在48 h达峰值。Tiron使PQ和75-1的诱导效果减弱,并使75-1对余水糯和浙辐802的互作由非亲和性互作转变为类似亲和性互作,导致侵染斑的形成。     

Feeding‐deterrent activity of α‐asarone isomers against some stored Coleoptera

All isomers of α‐asarone [(E)‐4‐prop‐1‐enyl‐1,2,5‐trimethoxybenzene] were tested for their feeding deterrent activity against adults of Sitophilus granarius and Tribolium confusum and larvae of Trogoderma granarium and Tribolium confusum. (E)‐2‐prop‐1‐enyl‐1,3,5‐trimethoxybenzene exhibited the strongest deterrent activity against all the species tested. The total coefficients of deterrency for this compound were 140.6 and 169.7 for Tribolium confusum adults and larvae, respectively, and 144.9 and 104.6 for larvae of Trogoderma granarium and adults of Sitophilus granarius, respectively. © 2000 Society of Chemical Industry     

水稻条斑病细菌类Harpin蛋白的纯化与特性研究

 用硫酸铵沉淀、制备等电聚焦电泳、阴离子交换层析等方法从水稻条斑病细菌(Xanthomonas oryzae pv. oryzicola,Xooc) RS105菌株突变体M51菌体破碎液中纯化出可激发烟草产生过敏性反应(hypersensitive response,HR)的蛋白类物质,分子量约为25.5 kDa。该物质与梨火疫病菌(Erwinia amylovora))的HarpinEa和水稻白叶枯病菌(Xanthomonas oryzae pv. oryzae,Xoo)的Harpin_Xoo具有相似的生物活性和理化特性:可激发烟草产生典型的HR反应;对热稳定,对蛋白酶K敏感;RNA转录抑制剂放线菌素D、蛋白质合成抑制剂环己酰亚铵和钙离子通道阻断剂氯化镧能够抑制该物质激发烟草产生HR;该物质具有诱导烟草抗TMV的功能。据此,将该物质命名为类Harpin蛋白(Harpin-like protein,HLP_Xooc)。     

Synthesis and Structure–Activity Relationships for the Fungicidal Activity of O,O-bisaryl sec-butylphosphonates

Sixteen O,O-bisaryl sec-butylphosphonates have been synthesised by condensing sec-butylphosphonyl dichloride with substituted phenols. The compounds were tested against two phytopathogenic fungi, Rhizoctonia bataticola and Helminthosporium oryzae. The most active compound against R. bataticola is O,O-bis(3-methylphenyl) sec-butylphosphonate (ED₅₀ 29·56 mg litre^-1) and against H. oryzae, O,O-bis(2-chlorophenyl) sec-butylphosphonate and its para-chloro analogue (ED₅₀ 0·14 and 0·13 mg litre^-1 respectively). Quantitative structure–activity relationships on the fungicidal activity have been analysed by means of multiple regression analysis using physicochemical substituent parameters. Electronic parameters viz., σ and F have expressed significant variability in fungitoxicity against both the fungi, viz. R. bataticola and H. oryzae. Hydrophobic and steric parameters are also found to be important in the correlation studies. © 1997 SCI.     

根癌农杆菌介导的稻瘟病菌近等菌系的构建与初步应用*

 利用根癌农杆菌C58C1介导转化1株致病力极弱的野生型稻瘟病菌菌株CY2,成功地获得3000多个转化子,混合接种于携带25个不同抗病单基因的水稻近等基因系上,获得4株单胞致病突变体;继代培养和PCR检测表明,这些突变体均为T-DNA插入CY2的后代,而非自发突变或外源菌株污染。将4株突变体与实验室已保存的20株致病突变体分别回接水稻近等基因系,推断其携带的致病基因类型,结果表明突变体分别针对13个抗性单基因的18个单基因系发生了突变,其中针对Pi-a,Pik-s,Pi-sh单基因系表现出较高的侵染频率。由于这些突变体均来自同一个菌株,仅致病性存在差异,属于近等菌系,利用其分析出102个水稻品种中的34个品种的抗病基因组成,其中,抗病基因Pik-s,Pi-a,Pi-sh,Pi-19(t)分布频率较高,分别达70.59%,61.76%,52.94%和44.12%,且带有这类基因的糯稻品种多于杂交水稻。     

Antifungal activity of 1,3-disubstituted symmetrical and unsymmetrical thioureas

1,3-disubstituted aliphatic and aromatic symmetrical and unsymmetrical thioureas were synthesised by novel routes and the antifungal activities of these compounds against two plant pathogens, Pyricularia oryzae and Drechslera oryzae were studied in Czapek-Dox medium at four different concentrations using acetone as the control and the structure-activity relationship among the substituted thioureas is reported. © 1998 SCI.     

施用硅肥锌肥作基肥对稻瘟病发生的影响

[目的]稻瘟病是水稻生产上的主要病害,本研究旨在探索水稻减药增效的有效生产措施,[方法]选址于湖北水稻稻瘟病常重发区咸宁市崇阳县原种场,以硅肥和锌肥作基肥,设置单位施用量不同的8个处理研究硅肥和锌肥对稻叶瘟、稻穗瘟的控制作用及对水稻产量的影响,[结果]结果表明,相比不施硅肥锌肥作基肥的对照,各施用微肥处理对稻叶瘟和稻穗瘟的发生均有控制作用,混合施用硅肥锌肥作基肥(硅+锌(225 kg/hm2+ 15 kg/hm2))对稻叶瘟和稻穗瘟的控制作用最佳,防效分别达84.98%和75.65%,病指分别由21.70和15.05降至3.26和3.58;各微肥处理对产量均有不同程度的增产作用。[结论]综上,本研究说明科学的硅肥处理不仅可有效地减少稻瘟病的发生,而且具有增产作用,可以作为水稻生产中减药增效的措施。     

黄豆豉和黑豆豉在发酵过程中的抗氧化性

通过米曲霉发酵黄豆和黑豆,测定豆豉的抗氧化能力.选用米曲霉发酵产生黄豆豉和黑豆豉,在相同条件下以还原力、DPPH自由基清除率、羟自由基清除率和总酚含量为指标,研究了黄豆豉和黑豆豉抗氧化性的变化及相关性分析.结果表明:黑豆豉比黄豆豉抗氧化性高.黄豆豉和黑豆豉在发酵第24 d时还原能力和总酚含量达到最高值,总酚含量分别为0.024 mg/mL,0.026 mg/mL.在发酵第27 d时黑豆豉和黄豆豉对(·OH)自由基和DPPH自由基的清除率达到最大,对(·OH)自由基清除率分别为40.12％、36.07％,对DPPH自由基的清除率分别为59.78％和64.86％.相关性分析结果表明黄豆豉还原力和羟自由基清除率与总酚含量之间相关性很高,而黑豆豉还原力和DPPH自由基清除率与总酚含量之间相关性都很高.