Chemical evaluation of some important varieties of onion (Allium cepa L.)

Five white and seven red varieties of onion were analysed for dry matter, carbohydrates, total phenols, coloring matter, lachrymatory factor and pyruvic acid content. Percent dry matter varied from 10.66 to 14.80. Total water soluble sugars, reducing sugars and total phenols ranged from 41.50 to 74.00, 12.00 to 22.25, and 1.75 to 2.95 percent (on a dry wt basis), respectively. The lachrymatory factor and pyruvic acid content ranged from 8.00 to 27.25 mg/100g and 6.18 to 13.27 micro moles/g respectively on a fresh wt basis. Red varieties contained a higher phenolic content than white ones. Varieties with higher phenolic content also had a greater amount of coloring matter in the dehydrated onions. The variety Punjab-48 was considered to be most suitable for dehydration purposes.     

Horticultural crops tackling stresses: genetic and epigenetic alterations

Genetic Resources and Crop Evolution - Food is indispensable for fulfilling the nutritional requirements of living beings. The principal source of food, nutrition and feed are horticultural...     

Investigating the effector suite profile of Australian Fusarium oxysporum isolates from agricultural and natural ecosystems

Pathogenic and putatively nonpathogenic isolates of Fusarium oxysporum are ubiquitously present in soils. Pathogenic isolates designated as formae speciales are very host specific. The genes that determine host-specific pathogenicity may be expected to be similar between strains within a forma specialis. Three different pathways were used for mining putative effectors from 85 assembled genome sequences representing isolates from the agricultural and natural ecosystems. A total of 436 putative effectors were identified, of which 115 were present in all the isolates. The presence–absence phylogeny showed some clustering of isolates based on the ecosystems, while some clustered with isolates from different ecosystems. Isolates from the agricultural and natural ecosystems shared 358 putative effectors. Agricultural isolates had 78 unique putative effectors, while isolates from the natural ecosystems had no unique effectors. Isolates from the natural ecosystems had effectors that have previously been confirmed with virulence functions in other filamentous fungi, suggesting that the natural ecosystems may be acting as a reservoir for pathogenic isolates awaiting compatible hosts. They also possessed putative effectors with domains involved in polysaccharide degradation. The putative effectors in the natural ecosystem isolates may be important for both parasitic and ecological fitness. Further analysis of the three characterized ff. sp.—lycopersici, niveum, and pisi—revealed high conservation in the pathogenicity mechanism in F. oxysporum. However, each strain had unique putative effectors, which may be responsible for host specificity.     

Trichoderma sp. endochitinase and β-1,3-glucanase impede Rhizoctonia solani growth independently,and their combined use does not enhance impediment

Rhizoctonia solani causing rice sheath blight is responsible for significant crop yield losses. Trichoderma spp., biological control agents, have been reported to antagonize R. solani through coordinated action of several cell wall-degrading enzymes including endochitinase and β-1,3-glucanase. In this study two antifungal genes, encoding endochitinase and β-1,3-glucanase, isolated from Trichoderma sp. antagonistic to R. solani, were cloned individually in His-tagged expression vectors and mobilized in Escherichia coli for protein expression. The purified proteins assayed in vitro with R. solani impeded pathogen growth independently by causing hyphal distortions revealed through scanning electron microscopy. The combined use of endochitinase and β-1,3-glucanase did not enhance the inhibition. The distortions caused by endochitinase were due to catalytic activity of Glu172 and Asp241 residues on glycosidic linkages in chitin polymers, whereas Glu628, Tyr631, and Asp569 in β-1,3-glucanase targeted glucan polymers. The distinctions of this study from earlier reports are (a) chitin polymers in the R. solani cell wall are exposed and not embedded within the β-glucan matrix; (b) chitin and β-1,3-glucan are vital polymers in the R. solani cell wall, rather than chitin as the only main polymer; and (c) hyphal tips of R. solani remain unaffected after an antifungal assay with endochitinase and β-1,3-glucanase, instead of exhibiting distortion.     

Classification of Rice Based on Statistical Analysis of Pasting Properties and Apparent Amylose Content: The Case of Oryza glaberrima Accessions from Africa

The diversity of 1,020 Oryza glaberrima rice accessions being kept at the Genetic Resources Unit of the Africa Rice Center with a varied range of apparent amylose content (AAC) and pasting properties was explored with cluster analysis. Rice cultivars are usually characterized according to grain dimensions, AACs, and gelatinization temperatures; however, this work focused on grouping African rice accessions based on their pasting properties and AAC. Using the Ward method of hierarchical cluster analysis, 1,020 rice accessions were initially distributed into five major clusters and further into 23 subclusters. The distribution pattern indicated that clusters I, II, III, IV, and V formed 27.6, 10.2, 15.8, 23.7, and 22.6% of the entire population, respectively. Although some of the groups had similar AAC, their pasting properties were very different, making it imperative for further investigations. Peak viscosity highly correlated (P < 0.01) with trough, breakdown, and final viscosities in all five clusters, whereas correlation between peak viscosity and AAC was not significant within clusters II and IV. Additionally, this categorization serves as a tool for exploring materials that can be employed in the development of rice cultivars for specific end uses.     

Cold Stress Injury during the Pod-Filling Phase in Chickpea (Cicer arietinum L.): Effects on Quantitative and Qualitative Components of Seeds

Chilling stress (<10 °C) is detrimental for chickpea, especially at the reproductive phase and leads to abortion of flowers, pods and impaired seed filling, causing severe reduction in yield. The information on the effects of low temperature during different pod-filling stages on quality and quantity of developing seeds is lacking in chickpea and hence this study. In this study, chickpea plants growing under warm conditions of the glasshouse were subjected to cold conditions of the field at the two stages, (a) early pod-filling and (b) late pod-filling, and subsequently analysed for stress injury in terms of electrolyte leakage (EL), 2,3,5-triphenyl tetrazolium chloride reduction, relative leaf water content and total chlorophyll content in the leaves of control and cold-stressed plants. Cold stress caused elevation of EL but reduced all the other parameters. Sucrose content decreased significantly in the leaves of cold-stressed plants. The differences between the effects of stress at two stages on the total plant dry weight were small and insignificant. The seed growth rate, seed fill duration, seed number, and average seed weight and size decreased greatly in the plants cold-stressed at the late pod-filling stage than those stressed at the early pod-filling stage. Greater reduction was observed in starch, proteins, soluble sugars, fat, crude fibre and storage protein fractions in the seeds of the plants cold-stressed at the late pod-filling stage. This coincided with a larger decrease in sucrose content, the activities of sucrose synthase, invertase and starch synthase observed at this stage. The germination and growth potential were, however, inhibited to a greater extent in seeds of plants stressed at the early pod-filling stage.     

Epidemiological studies on abortions in Indian thoroughbred mares

Young mares up to 8 years of age accounted for 41.55 percent of abortions. Forty and one quarter (40.25) percent of abortions were recorded in the 8th month of gestation. Twin abortions were 25.98 per cent and correlated directly to overall abortions.     

A new redox cofactor in eukaryotic enzymes: 6-hydroxydopa at the active site of bovine serum amine oxidase

An active site, cofactor-containing peptide has been obtained in high yield from bovine serum amine oxidase. Sequencing of this pentapeptide indicates: Leu-Asn-X-Asp-Tyr. Analysis of the peptide by mass spectrometry, ultraviolet-visible spectroscopy, and proton nuclear magnetic resonance leads to the identification of X as 6-hydroxydopa. This result indicates that, contrary to previous proposals, pyrroloquinoline quinone is not the active site cofactor in mammalian copper amine oxidases. Although 6-hydroxydopa has been implicated in neurotoxicity, the data presented suggest that this compound has a functional role at an enzyme active site.     

Response of Antioxidant Enzymes,Phytochelatins and Glutathione Production Towards Cd and Zn Stresses in Cajanus cajan (L.) Millsp. Genotypes Colonized by Arbuscular Mycorrhizal Fungi

Most metal polluted natural environments are contaminated with multiple metals, and arbuscular mycorrhizal (AM) fungi are among the extracellular strategies to avoid metal toxicity. To understand the interaction between Cd, Zn and AM fungi Glomus mosseae, two genotypes (Sel 85N and P792) of pigeonpea (Cajanus cajan L. Millsp.), differing in their metal tolerance, were chosen for study. Results revealed that root dry weights were more severely affected than shoot dry weights as both the metals were accumulated in roots than in the aerial parts. Mycorrhization promoted biomass yields by decreasing metal content in plant tissues. Exposure to the metals resulted in oxidative burst (high H₂O₂, malondialdehyde contents and electrolyte leakage), which was accompanied by decreased membrane stability. However, increase in the level of total non‐protein thiols (TNP‐SH) and the activity of antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and glutathione reductase (GR) suggested that all these parameters were synergistic in combating heavy‐metal‐induced oxidative stress. Zn supplementation proved to be inhibitory for Cd‐induced oxidative stress. AM fungi alleviated oxidative stress through enhanced production of TNP‐SH as well as through upregulation of antioxidant enzymes. Sel 85N exhibited lesser oxidative damage and more efficient defence mechanism than P792.