Enzymatic release of ferulic acid fromIpomoea batatas L. (sweet potato) stem

Ferulic acid is a phenolic compound that serves as a major biosynthetic precursor of vanillin in higher plants. We investigated the ability of the 3 commercial enzymes—Ultraflo L, Viscozyme L, and α-Amylase—to induce the release ferulic acid from theIpomoea batatas L. (sweet potato) stem. The rate of release for ferulic acid was optimal when Ultraflo L (1.0%) was used compared with the other enzymes, whereas Viscozyme L was most effective for the release of vanillic acid and vanillin. Thus, these enzymes may be useful for the large-scale production of ferulic acid and other phenolic compounds from sweet potato stem.     

Co-limitation of potato growth by Potato Cyst Nematode (Globodera rostochiensis) and Rhizoctonia solani

Globodera rostochiensis and Rhizoctonia solani are the most important growth limiting factors influencing potato production in Iran. The effects of inoculation with Potato Cyst Nematodes (PCN) (0, 50, 75 and 100 cysts/3.5?kg soil) and R. solani (with or without inoculation) on potato growth and development were investigated in cultivars Santé and Marfona. Inoculation with R. solani induced severe damage, especially when inoculation was accompanied with high density of PCN. The damage caused by R. solani tended to increase with an increase in PCN density, especially in Marfona. In Santé, number of stems or branches per plant significantly increased by inoculation with R. solani, while in Marfona it was significantly affected either by R. solani inoculation or PCN density. In Santé, number of stolons per plant was significantly increased by PCN, but not by R. solani. In Marfona, however, the number of stolons per plant was significantly affected either by R. solani inoculation or by presence of PCN, but not affected by PCN density. The general effect of R. solani or PCN inoculation treatments on shoot, below-ground and total dry weight of potato was significant, but strongly affected by cultivar. In general, our study supports the synergistic interaction between R. solani and PCN and its moderation by the use of a resistant cultivar such as Santé.     

The use of fluorescent reporter protein tagging to study the interaction between Root‐Knot Nematodes and Soft Rot Enterobacteriaceae

The study of plant parasitic nematodes such as Meloidogyne spp. and their interactions with phytopathogenic bacteria remains underexplored. One of the challenges towards establishing such interactions is the dependence on symptom development as a measure of interaction. In this study, mCherry was employed as a reporter protein to investigate the interaction between the soft rot Enterobacteriaceae (SRE) Pectobacterium carotovorum subsp. brasiliensis (Pcb) and root‐knot nematode (M. incognita). Pectobacterium carotovorum subsp. brasiliensis was transformed with pMP7604 generating Pcb_mCherry strain. This strain was shown to attach to the surface coat of M.incognita J2 at the optimum temperature of 28°C. This suggests that RKN juveniles may play a role in disseminating Pcb in soils that are heavily infested with Pcb. The presence of RKN juveniles was shown to play a role in introducing Pcb_mCherry into potato tubers potentially acting as a source of latent tuber infections.

Significance and Impact of the Study

This study uses fluorescent reporter protein tagging as a tool to demonstrate the interaction between root‐knot nematode (Meloidogyne incognita) and the soft rot Enterobacteriacea (Pectobacterium carotovorum subsp. brasiliensis). Introduction of Pectobacterium through wounds generated by second‐stage juveniles (J2) into potato tubers was demonstrated. These results suggest that RKN juveniles can facilitate latent infection of potato tubers in the soil. These findings have important implications in the management of RKN and SRE in seed potato production. Furthermore, this tool can be used to study other nematode–bacteria interactions that have not been previously studied.     

Phenotypic markers of Phytophthora infestans

Abstract

Phytophthora infestans is one of the most destructive pathogens of potato and causal agents of notorious disease late blight. Different chemicals are used to control the pathogen of late blight but the most commonly used is metalaxyl; its extensive use of has caused decreased sensitivity in the P. infestans population. The metalaxyl sensitivity of the Pakistani population of P. infestans is investigated in the present study. For this purpose, 178 isolates of P. infestans were obtained from the lesions of diseased potato leaves and stems, and samples were collected from the different potato-growing areas of Pakistan, where late blight is a problem. Sensitivity of the isolates of P. infestans was investigated by metalaxyl sensitivity test and with the help of test isolates were divided into three categories, i.e. sensitive, intermediate and resistant, based on their Co-efficient of mycelial growth inhibition (CMGI) values. During the study, highest percentage (50.17%) of resistant isolates was observed in the population of Punjab (zone 2), whereas the lower percentage (33.33%) was observed in the population of Swat valley (zone 6b). In the present study, it was discovered that P. infestans late blight-causing fungus has adopted more resistance against metalaxyl because of its wide use.     

Fusarium pallidoroseum L. on castor (Ricinus communis) in Samaru,Nigeria

Diseased castor leaves were collected from the Institute for Agricultural Research (IAR) fields and taken to the laboratory for isolation. Leaves were grown on Potato Dextrose Agar with Streptomycin and incubated for seven days. Grown cultures were observed under microscope and Fusarium pallidoroseum was isolated as confirmed by IMI. Inoculated leaves showed symptoms of wilts and blight.     

Effect of mineral oil on Potato virus Y acquisition by Rhopalosiphum padi

Seed potato crops are currently sprayed weekly with mineral oil to prevent transmission of the Potato virus Y (PVY; Potyviridae: Potyvirus), one of the most prevalent and important non‐persistent viruses affecting potato production. In spite of its wide usage as inhibitor of virus transmission, the mode of action for mineral oil is poorly known. The objective of this study was to quantify the effect of dosage and time from application of mineral oil on the inhibition of PVY acquisition. The bird cherry‐oat aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae), known as vector of PVY, was used in all the experiments. The results indicated that mineral oil efficiently decreased PVY acquisition by 75 and 70% 1 day after application of 5 and 10 l ha^?1, respectively. The inhibition effect decreased with time from application; mineral oil inhibits acquisition for less than 4 days at 5 l ha^?1 and between 8 and 12 days at 10 l ha^?1. As mineral oil was detected in the body of fewer aphids when they fed on plants 1 day after oil application, a change in the aphid probing behaviour on mineral oil‐treated plants was deduced. These results support the hypothesis that mineral oil physically inhibits the binding of the virus at the tip of the stylets.     

The Piperaceae Amides I: Structure of Pipercide,A New Insecticidal Amide from Piper nigrum L.

It was evidenced that mutagenic principles in tryptophan pyrolysate, 3-amino-1,4-dimethyl-5H pyrido(4,3-b) indole and 3-amino-1-methyl-5H pyrido(4,3-b) indole (abbreviated as Trp-P-1 and Trp-P-2, respectively) bind to DNA without activation by rat liver microsomes. The bindings of Trp-P-1 and Trp-P-2 were not random and did not introduce strand scissions into DNA. Trp-P-1 bound more easily than Trp-P-2. The bindings of these mutagenic principles to DNA were concluded by using negatively superhelical simian virus 40 (SV40) DNA from following experimental data. (1) The intensity of ethidium bromide (EtBr)-DNA fluorescence by illumination with UV light and the electrophoretic mobility of superhelical DNA in agarose gel decreased as a function of the amounts of Trp-P-1 and Trp-P-2. (2) In vitro RNA synthesis catalyzed by Escherichia coli DNA-dependent RNA polymerase and nick-translation catalyzed by Escherichia coli DNA polymerase I (Kornberg enzyme) were inhibited significantly on DNA treated with Trp-P-1 and Trp-P-2. (3) The negative superhelicity of SV40 DNA introduces unpaired regions into DNA. These regions can be cleaved by single-strand-specific S1 endonuclease to generate unit length linear duplex molecules. It was found that this S1-sensitivity of DNA decreased by treatment with Trp-P-1. (4) The cleavage patterns of Trp-P-1 treated DNA with five restriction endonucleases were investigated. The protection of the cleavage site by the drug was observed against HincII, HindIII and EcoRII, whereas not against HaeIII and HinfI. These results show that the binding of Trp-P-1 to DNA is not random. Identical results were also obtained in Trp-P-2.

However, the bindings of Trp-P-1 and Trp-P-2 were not so tight, and phenol extraction of the complex dissociated these drugs from DNA.     

Biosynthesis of Cercosporin

¹³C NMR spectra were measured for 19 pyrethroids and their related compounds including allethrin, tetramethrin, resmethrin, furamethrin, phenothrin and permethrin. Complete assignment of chemical shifts was accomplished by relative spectral pattern, single-frequency off-resonance decoupling, benzene substituent effects, proton selective decoupling and use of shift reagents. The use of shift reagent was found to be especially efficient for assignment of ¹³C resonances. In the case of allethrin, the splittings of some resonance peaks were observed originating from diastereomerism.     

Characterization of a Vitamin B12 Compound in the Edible Purple Laver,Porphyra yezoensis

The edible purple laver, Porphyra yezoensis, contained 51.49±1.51 μg of vitamin B₁₂ compounds per 100 g dry weight of the laver (mean±SEM, n=4). A vitamin B₁₂ compound was purified from the lyophilized purple laver and partially characterized. The silica gel 60 TLC and reversed-phase HPLC patterns of the purified pink-colored compound were identical to those of authentic vitamin B₁₂, but not to those of vitamin B₁₂ analogues inactive for humans.     

Effect of repeated harvesting on the content of caffeic acid and seven species of caffeoylquinic acids in sweet potato leaves

The purpose of this study was to investigate the effect of repeated harvesting on the content of caffeic acid (CA) and seven species of caffeoylquinic acids (CQAs) in sweet potato leaves using a newly developed high-performance liquid chromatography method. Six cultivars and two breeding lines were used in this study. Leaves were collected at monthly intervals from 1st harvest (May) to 4th harvest (August) in 2011 and 2012. ANOVA analysis revealed that the contents of CQAs were significantly different among all cultivars and breeding lines, but no significant differences were found for CA. No annual variation was confirmed in CA and CQAs. Repeated harvest of sweet potato leaves affected the content of only 4-CQA and 5-CQA. Post-hoc comparisons using Tukey’s method indicated that the contents of 4-CQA and 5-CQA in sweet potato leaves harvested at first time were significantly higher compared to those at the other harvest times.