Local comparison of the genomes of Mycobacterium tuberculosis and Mycobacterium leprae using the polymerase chain reaction

Abstract A gene fusion between the Saccharomyces cerevisiae actin gene promoter and the cDNA of the Fusarium solani f. sp. pisi pelA gene has been constructed. This expression cassette has been introduced into the industrial wine yeast strain T₇₃. The resulting recombinant strain is able to secrete active PELA enzyme into the culture medium. In preliminary microvinification experiments the wine produced by this pectinolytic strain is indistinguishable from wine produced using the non-transformed strain on the basis of the chemical analyses. Large scale fermentations need to be carried out in order to assess the effects on filtrability.     

蔓割病不同抗性甘薯品种的茎部细胞结构观察

蔓割病是我国南方薯区甘薯主要病害之一,本研究采用直接观察、显微和超微结构观测等方法,对高抗、中感和高感蔓割病的3个甘薯品种(高抗品种:金山57,中感品种:热薯1号,高感品种:新种花)接种蔓割病菌28 d植株充分发病后其茎基部细胞的侵染结构进行了观察。结果表明,在用清水作对照处理时,3个品种茎部组织的细胞形态和结构正常且完整,细胞代谢强。高抗品种金山57无论是接种组还是对照组,均未发现病原菌丝的存在,其茎下部、中部和上部细胞结构相对完整。中感品种热薯1号,蔓割病菌从其茎基部侵入后导致茎基部细胞破损坏死,而中部寄主-病原互作较为活跃和典型,造成养分运输受阻,茎基部接种后病原菌丝会沿着寄主茎部的维管束和其他组织一直向寄主的茎部末端蔓延,遭受侵染后的部位其细胞反应与高感品种新种花类似。高感品种新种花遭受蔓割病原菌侵染后,病原菌菌丝从茎基部新鲜剪口侵入后进入表皮细胞、皮层、维管束并在甘薯茎基部蔓延至中部、上部,直至寄主整株枯死,甘薯茎的木质部导管出现侵填体,质壁分离;与此同时,细胞壁的沉积物及乳突在病原菌的入侵处形成,各种无定型物质或纤丝构成的织网迅速包围入侵菌丝。     

An improved test for evaluating the pathogenicity of isolates of Fusarium solani f.sp. pisi on pea

An improved in vitro test is described for determining the pathogenicity of Fusarium solani f.sp. pisi isolates on pea. This technique involves the use of polypropylene fibre Milcap plugs to suspend peas in boiling tubes containing spore suspensions in 0.1% water agar. Results were available after 14 days of incubation at 25°C. Four levels of pathogenicity were detected on pea cultivars Little Marvel and Dark Skinned Perfection using a total of eight isolates and strains of F. solani f.sp. pisi.     

Droopy: a wilty mutant of potato deficient in abscisic acid

Abstract. Droopy mutant of potato ( Solanum tubero-sum L., group Pliureja ) wilts because of excessive stomatal opening (Waggoner & Simmonds, 1966). Progeny of the cross between potato clones C.P.C. 4461 and C.P.C. 4463 showed characteristics similar to those of the original droopy potato. These plants wilted at high vapour pressure deficit and their stomatal conductances in the light and the dark were higher than those of normal plants. Conductances were reduced by applied abscisic acid (ABA), but stomata remained partially open even when guard cells were plasmolysed. Leaves of droopy plants accumulated very little ABA when water-stressed.     

Roles of glycosylation on the antifungal activity and apoplast accumulation of StAPs (Solanum tuberosum aspartic proteases)

Specific roles of glycosylation appear to be protein-dependent. Plant aspartic proteases (APs) contain two or more consensus N-glycosylation sites; however, the importance of them is not well understood. StAPs (Solanum tuberosum aspartic proteases) are bifunctional proteins with both proteolytic and antimicrobial activities. These proteins are accumulated into the intercellular washing fluid of potato tubers and leaves after wounding or infection. In this paper we investigated the importance of glycosylation on the StAPs apoplast accumulation, biochemical parameters, and fungicidal activity. Assays to evaluate the importance of StAPs glycosylation groups by using glycosylation inhibitors demonstrate that carbohydrate portions are essential to StAPs accumulation into the apoplast of tubers and leaves after wounding or detachment, respectively. Bifunctional activity of StAPs is differentially affected by this post-translational modification. Results obtained show that not significant changes were produced in the physicochemical properties after StAPs deglycosylation (pH and thermal-optimum activity and index of protein surface hydrophobicity). Otherwise, StAPs antifungal activity is affected by deglycosylation. Deglycosylated StAPs (dgStAPs) fungicidal activity is lower than native StAPs at all concentrations and times assayed. In summary, glycosylation has not a significant role on the StAPs conformational structure. However, it is involved in the StAPs subcellular accumulation and antifungal activity suggesting that it could be necessary for StAPs membrane and/or protein interactions and subsequently its biological function(s).     

甘薯根腐病菌侵染对甘薯内源激素水平的影响

甘薯根腐病病原菌[Fusarium solani(Mart.)Sacc.f.sp.batatas McClure,简称FSB]侵染及其培养液滤液处理高敏感性甘薯品种‘胜利百号’后,引起甘薯叶片、茎尖和根部组织内源ABA含量大幅升高。其中在根部出现最早,但茎尖中积累浓度最高。侵染后甘薯叶片、茎尖和根部组织内源GA1/3含量显著低于对照。甘薯组培苗经FSB培养滤液处理9h后,ABA含量显著上升,处理15h,ABA含量呈下降趋势,而GA1/3含量在101和102稀释液处理15h(103稀释液处理12h)时出现显著上升。这些结果有助于解释甘薯根腐病株矮小不产生藤蔓,并在秋季大量现蕾开花的生理现象。     

An extracellular enzyme from Fusarium solani f. sp. phaseoli which catalyses hydration of the isoflavonoid phytoalexin, phaseollidin

Among the antimicrobial phytoalexins produced by Phaseolus vulgaris (French bean) are the prenylated isoflavonoids kievitone and phaseollidin. Two enzyme activities, kievitone hydratase and phaseollidin hydratase, occur in culture filtrates of the bean pathogen, Fusarium solani f. sp. phaseoli, and catalyse similar hydration reactions on the dimethylallyl moieties of the phytoalexins. The enzymes nearly co-purified during hydroxyapatite chromatography followed by preparative native gel electrophoresis. Eluates from successive slices taken from the native gel were assayed for both activities. Although they were not completely separated in the native gel, the activity profiles indicated that the two activities were distinct. The Km of phaseollidin hydratase for phaseollidin was approximately 7 microM.     

香蕉枯萎病菌果胶甲基酯酶基因的克隆与生物信息学分析

旨在了解香蕉枯萎病菌(Fusarium oxysporumf.sp.cubense)4号生理小种(FOC4)PME基因序列特征,根据同源物种PME相关序列设计引物,利用PCR和RT-PCR技术,克隆FOC4序列基因和开放阅读框,命名为Foc4Pme。结果表明,所获得的PME基因均含有2个内含子和3个外显子,990 bp的片段,编码329个氨基酸。预测编码蛋白有信号肽,具有1个功能位点,其分子质量和等电点分为34.894 8 kD和9.17,该蛋白为稳定存在的蛋白。该蛋白疏水性最大值为2.022,最小值为-2.156,大部分区域为亲水区。该基因编码的蛋白具有一定保守性,进化上与镰刀菌亲缘关系最近。     

Induced Resistance in Cucumbers against Fusarium oxysporum f. sp. cucumerinum and Rhizoctonia solani AG2–2 by Infection of the Cotyledons

Localized infection in cucumber cotyledons with Colletotrichum lagenarium induced resistance against infection after challenge inoculation with Rhizoctonia solani AG2–2 and Fusarium oxysporum f. sp. cucumerinum in the roots. The plants were unprotected in soil that was infested heavily with R. solani or in contact with the mycelium, and induced resistance was not observed. Wounding of the root also negated the effect of induced resistance to F. oxysporum .     

Identification of I‐7 expands the repertoire of genes for resistance to Fusarium wilt in tomato to three resistance gene classes

The tomato I‐3 and I‐7 genes confer resistance to Fusarium oxysporum f. sp. lycopersici (Fol) race 3 and were introgressed into the cultivated tomato, Solanum lycopersicum, from the wild relative Solanum pennellii. I‐3 has been identified previously on chromosome 7 and encodes an S‐receptor‐like kinase, but little is known about I‐7. Molecular markers have been developed for the marker‐assisted breeding of I‐3, but none are available for I‐7. We used an RNA‐seq and single nucleotide polymorphism (SNP) analysis approach to map I‐7 to a small introgression of S. pennellii DNA (c. 210 kb) on chromosome 8, and identified I‐7 as a gene encoding a leucine‐rich repeat receptor‐like protein (LRR‐RLP), thereby expanding the repertoire of resistance protein classes conferring resistance to Fol. Using an eds1 mutant of tomato, we showed that I‐7, like many other LRR‐RLPs conferring pathogen resistance in tomato, is EDS1 (Enhanced Disease Susceptibility 1) dependent. Using transgenic tomato plants carrying only the I‐7 gene for Fol resistance, we found that I‐7 also confers resistance to Fol races 1 and 2. Given that Fol race 1 carries Avr1, resistance to Fol race 1 indicates that I‐7‐mediated resistance, unlike I‐2‐ or I‐3‐mediated resistance, is not suppressed by Avr1. This suggests that Avr1 is not a general suppressor of Fol resistance in tomato, leading us to hypothesize that Avr1 may be acting against an EDS1‐independent pathway for resistance activation. The identification of I‐7 has allowed us to develop molecular markers for marker‐assisted breeding of both genes currently known to confer Fol race 3 resistance (I‐3 and I‐7). Given that I‐7‐mediated resistance is not suppressed by Avr1, I‐7 may be a useful addition to I‐3 in the tomato breeder's toolbox.